diff options
Diffstat (limited to 'Documentation/userspace-api')
22 files changed, 949 insertions, 80 deletions
diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst index 59472cd6a11d..2a198838fca9 100644 --- a/Documentation/userspace-api/ioctl/ioctl-number.rst +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst @@ -339,6 +339,7 @@ Code Seq# Include File Comments 0xB4 00-0F linux/gpio.h <mailto:linux-gpio@vger.kernel.org> 0xB5 00-0F uapi/linux/rpmsg.h <mailto:linux-remoteproc@vger.kernel.org> 0xB6 all linux/fpga-dfl.h +0xB7 all uapi/linux/remoteproc_cdev.h <mailto:linux-remoteproc@vger.kernel.org> 0xC0 00-0F linux/usb/iowarrior.h 0xCA 00-0F uapi/misc/cxl.h 0xCA 10-2F uapi/misc/ocxl.h diff --git a/Documentation/userspace-api/media/cec/cec-ioc-adap-g-caps.rst b/Documentation/userspace-api/media/cec/cec-ioc-adap-g-caps.rst index 94e46a11d68d..436a882dfa31 100644 --- a/Documentation/userspace-api/media/cec/cec-ioc-adap-g-caps.rst +++ b/Documentation/userspace-api/media/cec/cec-ioc-adap-g-caps.rst @@ -58,6 +58,9 @@ returns the information to the application. The ioctl never fails. - The name of this CEC adapter. The combination ``driver`` and ``name`` must be unique. * - __u32 + - ``available_log_addrs`` + - The maximum number of logical addresses that can be configured. + * - __u32 - ``capabilities`` - The capabilities of the CEC adapter, see :ref:`cec-capabilities`. diff --git a/Documentation/userspace-api/media/dvb/fe-get-info.rst b/Documentation/userspace-api/media/dvb/fe-get-info.rst index 80d9f8195ac4..6b3ffd301142 100644 --- a/Documentation/userspace-api/media/dvb/fe-get-info.rst +++ b/Documentation/userspace-api/media/dvb/fe-get-info.rst @@ -34,8 +34,7 @@ Arguments File descriptor returned by :ref:`open() <frontend_f_open>`. ``argp`` - pointer to struct struct - :c:type:`dvb_frontend_info` + pointer to struct :c:type:`dvb_frontend_info` Description diff --git a/Documentation/userspace-api/media/v4l/buffer.rst b/Documentation/userspace-api/media/v4l/buffer.rst index 951ae1ed485f..57e752aaf414 100644 --- a/Documentation/userspace-api/media/v4l/buffer.rst +++ b/Documentation/userspace-api/media/v4l/buffer.rst @@ -23,8 +23,8 @@ argument to the :ref:`VIDIOC_QUERYBUF`, :ref:`VIDIOC_QBUF <VIDIOC_QBUF>` and :ref:`VIDIOC_DQBUF <VIDIOC_QBUF>` ioctl. In the multi-planar API, some plane-specific members of struct :c:type:`v4l2_buffer`, -such as pointers and sizes for each plane, are stored in struct -struct :c:type:`v4l2_plane` instead. In that case, struct +such as pointers and sizes for each plane, are stored in +struct :c:type:`v4l2_plane` instead. In that case, struct :c:type:`v4l2_buffer` contains an array of plane structures. Dequeued video buffers come with timestamps. The driver decides at which @@ -577,7 +577,10 @@ Buffer Flags applications shall use this flag if the data captured in the buffer is not going to be touched by the CPU, instead the buffer will, probably, be passed on to a DMA-capable hardware unit for - further processing or output. + further processing or output. This flag is ignored unless the + queue is used for :ref:`memory mapping <mmap>` streaming I/O and + reports :ref:`V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS + <V4L2-BUF-CAP-SUPPORTS-MMAP-CACHE-HINTS>` capability. * .. _`V4L2-BUF-FLAG-NO-CACHE-CLEAN`: - ``V4L2_BUF_FLAG_NO_CACHE_CLEAN`` @@ -585,7 +588,10 @@ Buffer Flags - Caches do not have to be cleaned for this buffer. Typically applications shall use this flag for output buffers if the data in this buffer has not been created by the CPU but by some - DMA-capable unit, in which case caches have not been used. + DMA-capable unit, in which case caches have not been used. This flag + is ignored unless the queue is used for :ref:`memory mapping <mmap>` + streaming I/O and reports :ref:`V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS + <V4L2-BUF-CAP-SUPPORTS-MMAP-CACHE-HINTS>` capability. * .. _`V4L2-BUF-FLAG-M2M-HOLD-CAPTURE-BUF`: - ``V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF`` @@ -681,6 +687,36 @@ Buffer Flags \normalsize +.. _memory-flags: + +Memory Consistency Flags +======================== + +.. tabularcolumns:: |p{7.0cm}|p{2.2cm}|p{8.3cm}| + +.. cssclass:: longtable + +.. flat-table:: + :header-rows: 0 + :stub-columns: 0 + :widths: 3 1 4 + + * .. _`V4L2-FLAG-MEMORY-NON-CONSISTENT`: + + - ``V4L2_FLAG_MEMORY_NON_CONSISTENT`` + - 0x00000001 + - A buffer is allocated either in consistent (it will be automatically + coherent between the CPU and the bus) or non-consistent memory. The + latter can provide performance gains, for instance the CPU cache + sync/flush operations can be avoided if the buffer is accessed by the + corresponding device only and the CPU does not read/write to/from that + buffer. However, this requires extra care from the driver -- it must + guarantee memory consistency by issuing a cache flush/sync when + consistency is needed. If this flag is set V4L2 will attempt to + allocate the buffer in non-consistent memory. The flag takes effect + only if the buffer is used for :ref:`memory mapping <mmap>` I/O and the + queue reports the :ref:`V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS + <V4L2-BUF-CAP-SUPPORTS-MMAP-CACHE-HINTS>` capability. .. c:type:: v4l2_memory diff --git a/Documentation/userspace-api/media/v4l/colorspaces-details.rst b/Documentation/userspace-api/media/v4l/colorspaces-details.rst index 79ed6f4f76eb..300c5d2e7d0f 100644 --- a/Documentation/userspace-api/media/v4l/colorspaces-details.rst +++ b/Documentation/userspace-api/media/v4l/colorspaces-details.rst @@ -767,8 +767,8 @@ scaled to [-128…128] and then clipped to [-128…127]. information. So if something other than sRGB is used, then the driver will have to set that information explicitly. Effectively ``V4L2_COLORSPACE_JPEG`` can be considered to be an abbreviation for - ``V4L2_COLORSPACE_SRGB``, ``V4L2_YCBCR_ENC_601`` and - ``V4L2_QUANTIZATION_FULL_RANGE``. + ``V4L2_COLORSPACE_SRGB``, ``V4L2_XFER_FUNC_SRGB``, ``V4L2_YCBCR_ENC_601`` + and ``V4L2_QUANTIZATION_FULL_RANGE``. *************************************** Detailed Transfer Function Descriptions diff --git a/Documentation/userspace-api/media/v4l/dev-decoder.rst b/Documentation/userspace-api/media/v4l/dev-decoder.rst index 606b54947e10..3d4138a4ba69 100644 --- a/Documentation/userspace-api/media/v4l/dev-decoder.rst +++ b/Documentation/userspace-api/media/v4l/dev-decoder.rst @@ -247,7 +247,7 @@ Querying Capabilities Initialization ============== -1. Set the coded format on ``OUTPUT`` via :c:func:`VIDIOC_S_FMT` +1. Set the coded format on ``OUTPUT`` via :c:func:`VIDIOC_S_FMT`. * **Required fields:** @@ -803,7 +803,7 @@ it may be affected as per normal decoder operation. * The decoder will drop all the pending ``OUTPUT`` buffers and they must be treated as returned to the client (following standard semantics). -2. Restart the ``OUTPUT`` queue via :c:func:`VIDIOC_STREAMON` +2. Restart the ``OUTPUT`` queue via :c:func:`VIDIOC_STREAMON`. * **Required fields:** @@ -906,7 +906,9 @@ reflected by corresponding queries): * visible resolution (selection rectangles), -* the minimum number of buffers needed for decoding. +* the minimum number of buffers needed for decoding, + +* bit-depth of the bitstream has been changed. Whenever that happens, the decoder must proceed as follows: @@ -1059,7 +1061,7 @@ sequence was started. ``V4L2_DEC_CMD_STOP`` again while the drain sequence is in progress and they will fail with -EBUSY error code if attempted. - Although mandatory, the availability of decoder commands may be queried + Although not mandatory, the availability of decoder commands may be queried using :c:func:`VIDIOC_TRY_DECODER_CMD`. End of Stream diff --git a/Documentation/userspace-api/media/v4l/dev-encoder.rst b/Documentation/userspace-api/media/v4l/dev-encoder.rst new file mode 100644 index 000000000000..fb44f20924de --- /dev/null +++ b/Documentation/userspace-api/media/v4l/dev-encoder.rst @@ -0,0 +1,753 @@ +.. This file is dual-licensed: you can use it either under the terms +.. of the GPL 2.0 or the GFDL 1.1+ license, at your option. Note that this +.. dual licensing only applies to this file, and not this project as a +.. whole. +.. +.. a) This file is free software; you can redistribute it and/or +.. modify it under the terms of the GNU General Public License as +.. published by the Free Software Foundation version 2 of +.. the License. +.. +.. This file is distributed in the hope that it will be useful, +.. but WITHOUT ANY WARRANTY; without even the implied warranty of +.. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +.. GNU General Public License for more details. +.. +.. Or, alternatively, +.. +.. b) Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/userspace-api/media/fdl-appendix.rst. +.. +.. TODO: replace it to GPL-2.0 OR GFDL-1.1-or-later WITH no-invariant-sections + +.. _encoder: + +************************************************* +Memory-to-Memory Stateful Video Encoder Interface +************************************************* + +A stateful video encoder takes raw video frames in display order and encodes +them into a bytestream. It generates complete chunks of the bytestream, including +all metadata, headers, etc. The resulting bytestream does not require any +further post-processing by the client. + +Performing software stream processing, header generation etc. in the driver +in order to support this interface is strongly discouraged. In case such +operations are needed, use of the Stateless Video Encoder Interface (in +development) is strongly advised. + +Conventions and Notations Used in This Document +=============================================== + +1. The general V4L2 API rules apply if not specified in this document + otherwise. + +2. The meaning of words "must", "may", "should", etc. is as per `RFC + 2119 <https://tools.ietf.org/html/rfc2119>`_. + +3. All steps not marked "optional" are required. + +4. :c:func:`VIDIOC_G_EXT_CTRLS` and :c:func:`VIDIOC_S_EXT_CTRLS` may be used + interchangeably with :c:func:`VIDIOC_G_CTRL` and :c:func:`VIDIOC_S_CTRL`, + unless specified otherwise. + +5. Single-planar API (see :ref:`planar-apis`) and applicable structures may be + used interchangeably with multi-planar API, unless specified otherwise, + depending on encoder capabilities and following the general V4L2 guidelines. + +6. i = [a..b]: sequence of integers from a to b, inclusive, i.e. i = + [0..2]: i = 0, 1, 2. + +7. Given an ``OUTPUT`` buffer A, then A' represents a buffer on the ``CAPTURE`` + queue containing data that resulted from processing buffer A. + +Glossary +======== + +Refer to :ref:`decoder-glossary`. + +State Machine +============= + +.. kernel-render:: DOT + :alt: DOT digraph of encoder state machine + :caption: Encoder State Machine + + digraph encoder_state_machine { + node [shape = doublecircle, label="Encoding"] Encoding; + + node [shape = circle, label="Initialization"] Initialization; + node [shape = circle, label="Stopped"] Stopped; + node [shape = circle, label="Drain"] Drain; + node [shape = circle, label="Reset"] Reset; + + node [shape = point]; qi + qi -> Initialization [ label = "open()" ]; + + Initialization -> Encoding [ label = "Both queues streaming" ]; + + Encoding -> Drain [ label = "V4L2_ENC_CMD_STOP" ]; + Encoding -> Reset [ label = "VIDIOC_STREAMOFF(CAPTURE)" ]; + Encoding -> Stopped [ label = "VIDIOC_STREAMOFF(OUTPUT)" ]; + Encoding -> Encoding; + + Drain -> Stopped [ label = "All CAPTURE\nbuffers dequeued\nor\nVIDIOC_STREAMOFF(OUTPUT)" ]; + Drain -> Reset [ label = "VIDIOC_STREAMOFF(CAPTURE)" ]; + + Reset -> Encoding [ label = "VIDIOC_STREAMON(CAPTURE)" ]; + Reset -> Initialization [ label = "VIDIOC_REQBUFS(OUTPUT, 0)" ]; + + Stopped -> Encoding [ label = "V4L2_ENC_CMD_START\nor\nVIDIOC_STREAMON(OUTPUT)" ]; + Stopped -> Reset [ label = "VIDIOC_STREAMOFF(CAPTURE)" ]; + } + +Querying Capabilities +===================== + +1. To enumerate the set of coded formats supported by the encoder, the + client may call :c:func:`VIDIOC_ENUM_FMT` on ``CAPTURE``. + + * The full set of supported formats will be returned, regardless of the + format set on ``OUTPUT``. + +2. To enumerate the set of supported raw formats, the client may call + :c:func:`VIDIOC_ENUM_FMT` on ``OUTPUT``. + + * Only the formats supported for the format currently active on ``CAPTURE`` + will be returned. + + * In order to enumerate raw formats supported by a given coded format, + the client must first set that coded format on ``CAPTURE`` and then + enumerate the formats on ``OUTPUT``. + +3. The client may use :c:func:`VIDIOC_ENUM_FRAMESIZES` to detect supported + resolutions for a given format, passing the desired pixel format in + :c:type:`v4l2_frmsizeenum` ``pixel_format``. + + * Values returned by :c:func:`VIDIOC_ENUM_FRAMESIZES` for a coded pixel + format will include all possible coded resolutions supported by the + encoder for the given coded pixel format. + + * Values returned by :c:func:`VIDIOC_ENUM_FRAMESIZES` for a raw pixel format + will include all possible frame buffer resolutions supported by the + encoder for the given raw pixel format and coded format currently set on + ``CAPTURE``. + +4. The client may use :c:func:`VIDIOC_ENUM_FRAMEINTERVALS` to detect supported + frame intervals for a given format and resolution, passing the desired pixel + format in :c:type:`v4l2_frmsizeenum` ``pixel_format`` and the resolution + in :c:type:`v4l2_frmsizeenum` ``width`` and :c:type:`v4l2_frmsizeenum` + ``height``. + + * Values returned by :c:func:`VIDIOC_ENUM_FRAMEINTERVALS` for a coded pixel + format and coded resolution will include all possible frame intervals + supported by the encoder for the given coded pixel format and resolution. + + * Values returned by :c:func:`VIDIOC_ENUM_FRAMEINTERVALS` for a raw pixel + format and resolution will include all possible frame intervals supported + by the encoder for the given raw pixel format and resolution and for the + coded format, coded resolution and coded frame interval currently set on + ``CAPTURE``. + + * Support for :c:func:`VIDIOC_ENUM_FRAMEINTERVALS` is optional. If it is + not implemented, then there are no special restrictions other than the + limits of the codec itself. + +5. Supported profiles and levels for the coded format currently set on + ``CAPTURE``, if applicable, may be queried using their respective controls + via :c:func:`VIDIOC_QUERYCTRL`. + +6. Any additional encoder capabilities may be discovered by querying + their respective controls. + +Initialization +============== + +1. Set the coded format on the ``CAPTURE`` queue via :c:func:`VIDIOC_S_FMT`. + + * **Required fields:** + + ``type`` + a ``V4L2_BUF_TYPE_*`` enum appropriate for ``CAPTURE``. + + ``pixelformat`` + the coded format to be produced. + + ``sizeimage`` + desired size of ``CAPTURE`` buffers; the encoder may adjust it to + match hardware requirements. + + ``width``, ``height`` + ignored (read-only). + + other fields + follow standard semantics. + + * **Return fields:** + + ``sizeimage`` + adjusted size of ``CAPTURE`` buffers. + + ``width``, ``height`` + the coded size selected by the encoder based on current state, e.g. + ``OUTPUT`` format, selection rectangles, etc. (read-only). + + .. important:: + + Changing the ``CAPTURE`` format may change the currently set ``OUTPUT`` + format. How the new ``OUTPUT`` format is determined is up to the encoder + and the client must ensure it matches its needs afterwards. + +2. **Optional.** Enumerate supported ``OUTPUT`` formats (raw formats for + source) for the selected coded format via :c:func:`VIDIOC_ENUM_FMT`. + + * **Required fields:** + + ``type`` + a ``V4L2_BUF_TYPE_*`` enum appropriate for ``OUTPUT``. + + other fields + follow standard semantics. + + * **Return fields:** + + ``pixelformat`` + raw format supported for the coded format currently selected on + the ``CAPTURE`` queue. + + other fields + follow standard semantics. + +3. Set the raw source format on the ``OUTPUT`` queue via + :c:func:`VIDIOC_S_FMT`. + + * **Required fields:** + + ``type`` + a ``V4L2_BUF_TYPE_*`` enum appropriate for ``OUTPUT``. + + ``pixelformat`` + raw format of the source. + + ``width``, ``height`` + source resolution. + + other fields + follow standard semantics. + + * **Return fields:** + + ``width``, ``height`` + may be adjusted to match encoder minimums, maximums and alignment + requirements, as required by the currently selected formats, as + reported by :c:func:`VIDIOC_ENUM_FRAMESIZES`. + + other fields + follow standard semantics. + + * Setting the ``OUTPUT`` format will reset the selection rectangles to their + default values, based on the new resolution, as described in the next + step. + +4. Set the raw frame interval on the ``OUTPUT`` queue via + :c:func:`VIDIOC_S_PARM`. This also sets the coded frame interval on the + ``CAPTURE`` queue to the same value. + + * ** Required fields:** + + ``type`` + a ``V4L2_BUF_TYPE_*`` enum appropriate for ``OUTPUT``. + + ``parm.output`` + set all fields except ``parm.output.timeperframe`` to 0. + + ``parm.output.timeperframe`` + the desired frame interval; the encoder may adjust it to + match hardware requirements. + + * **Return fields:** + + ``parm.output.timeperframe`` + the adjusted frame interval. + + .. important:: + + Changing the ``OUTPUT`` frame interval *also* sets the framerate that + the encoder uses to encode the video. So setting the frame interval + to 1/24 (or 24 frames per second) will produce a coded video stream + that can be played back at that speed. The frame interval for the + ``OUTPUT`` queue is just a hint, the application may provide raw + frames at a different rate. It can be used by the driver to help + schedule multiple encoders running in parallel. + + In the next step the ``CAPTURE`` frame interval can optionally be + changed to a different value. This is useful for off-line encoding + were the coded frame interval can be different from the rate at + which raw frames are supplied. + + .. important:: + + ``timeperframe`` deals with *frames*, not fields. So for interlaced + formats this is the time per two fields, since a frame consists of + a top and a bottom field. + + .. note:: + + It is due to historical reasons that changing the ``OUTPUT`` frame + interval also changes the coded frame interval on the ``CAPTURE`` + queue. Ideally these would be independent settings, but that would + break the existing API. + +5. **Optional** Set the coded frame interval on the ``CAPTURE`` queue via + :c:func:`VIDIOC_S_PARM`. This is only necessary if the coded frame + interval is different from the raw frame interval, which is typically + the case for off-line encoding. Support for this feature is signalled + by the :ref:`V4L2_FMT_FLAG_ENC_CAP_FRAME_INTERVAL <fmtdesc-flags>` format flag. + + * ** Required fields:** + + ``type`` + a ``V4L2_BUF_TYPE_*`` enum appropriate for ``CAPTURE``. + + ``parm.capture`` + set all fields except ``parm.capture.timeperframe`` to 0. + + ``parm.capture.timeperframe`` + the desired coded frame interval; the encoder may adjust it to + match hardware requirements. + + * **Return fields:** + + ``parm.capture.timeperframe`` + the adjusted frame interval. + + .. important:: + + Changing the ``CAPTURE`` frame interval sets the framerate for the + coded video. It does *not* set the rate at which buffers arrive on the + ``CAPTURE`` queue, that depends on how fast the encoder is and how + fast raw frames are queued on the ``OUTPUT`` queue. + + .. important:: + + ``timeperframe`` deals with *frames*, not fields. So for interlaced + formats this is the time per two fields, since a frame consists of + a top and a bottom field. + + .. note:: + + Not all drivers support this functionality, in that case just set + the desired coded frame interval for the ``OUTPUT`` queue. + + However, drivers that can schedule multiple encoders based on the + ``OUTPUT`` frame interval must support this optional feature. + +6. **Optional.** Set the visible resolution for the stream metadata via + :c:func:`VIDIOC_S_SELECTION` on the ``OUTPUT`` queue if it is desired + to be different than the full OUTPUT resolution. + + * **Required fields:** + + ``type`` + a ``V4L2_BUF_TYPE_*`` enum appropriate for ``OUTPUT``. + + ``target`` + set to ``V4L2_SEL_TGT_CROP``. + + ``r.left``, ``r.top``, ``r.width``, ``r.height`` + visible rectangle; this must fit within the `V4L2_SEL_TGT_CROP_BOUNDS` + rectangle and may be subject to adjustment to match codec and + hardware constraints. + + * **Return fields:** + + ``r.left``, ``r.top``, ``r.width``, ``r.height`` + visible rectangle adjusted by the encoder. + + * The following selection targets are supported on ``OUTPUT``: + + ``V4L2_SEL_TGT_CROP_BOUNDS`` + equal to the full source frame, matching the active ``OUTPUT`` + format. + + ``V4L2_SEL_TGT_CROP_DEFAULT`` + equal to ``V4L2_SEL_TGT_CROP_BOUNDS``. + + ``V4L2_SEL_TGT_CROP`` + rectangle within the source buffer to be encoded into the + ``CAPTURE`` stream; defaults to ``V4L2_SEL_TGT_CROP_DEFAULT``. + + .. note:: + + A common use case for this selection target is encoding a source + video with a resolution that is not a multiple of a macroblock, + e.g. the common 1920x1080 resolution may require the source + buffers to be aligned to 1920x1088 for codecs with 16x16 macroblock + size. To avoid encoding the padding, the client needs to explicitly + configure this selection target to 1920x1080. + + .. warning:: + + The encoder may adjust the crop/compose rectangles to the nearest + supported ones to meet codec and hardware requirements. The client needs + to check the adjusted rectangle returned by :c:func:`VIDIOC_S_SELECTION`. + +7. Allocate buffers for both ``OUTPUT`` and ``CAPTURE`` via + :c:func:`VIDIOC_REQBUFS`. This may be performed in any order. + + * **Required fields:** + + ``count`` + requested number of buffers to allocate; greater than zero. + + ``type`` + a ``V4L2_BUF_TYPE_*`` enum appropriate for ``OUTPUT`` or + ``CAPTURE``. + + other fields + follow standard semantics. + + * **Return fields:** + + ``count`` + actual number of buffers allocated. + + .. warning:: + + The actual number of allocated buffers may differ from the ``count`` + given. The client must check the updated value of ``count`` after the + call returns. + + .. note:: + + To allocate more than the minimum number of OUTPUT buffers (for pipeline + depth), the client may query the ``V4L2_CID_MIN_BUFFERS_FOR_OUTPUT`` + control to get the minimum number of buffers required, and pass the + obtained value plus the number of additional buffers needed in the + ``count`` field to :c:func:`VIDIOC_REQBUFS`. + + Alternatively, :c:func:`VIDIOC_CREATE_BUFS` can be used to have more + control over buffer allocation. + + * **Required fields:** + + ``count`` + requested number of buffers to allocate; greater than zero. + + ``type`` + a ``V4L2_BUF_TYPE_*`` enum appropriate for ``OUTPUT``. + + other fields + follow standard semantics. + + * **Return fields:** + + ``count`` + adjusted to the number of allocated buffers. + +8. Begin streaming on both ``OUTPUT`` and ``CAPTURE`` queues via + :c:func:`VIDIOC_STREAMON`. This may be performed in any order. The actual + encoding process starts when both queues start streaming. + +.. note:: + + If the client stops the ``CAPTURE`` queue during the encode process and then + restarts it again, the encoder will begin generating a stream independent + from the stream generated before the stop. The exact constraints depend + on the coded format, but may include the following implications: + + * encoded frames produced after the restart must not reference any + frames produced before the stop, e.g. no long term references for + H.264/HEVC, + + * any headers that must be included in a standalone stream must be + produced again, e.g. SPS and PPS for H.264/HEVC. + +Encoding +======== + +This state is reached after the `Initialization` sequence finishes +successfully. In this state, the client queues and dequeues buffers to both +queues via :c:func:`VIDIOC_QBUF` and :c:func:`VIDIOC_DQBUF`, following the +standard semantics. + +The content of encoded ``CAPTURE`` buffers depends on the active coded pixel +format and may be affected by codec-specific extended controls, as stated +in the documentation of each format. + +Both queues operate independently, following standard behavior of V4L2 buffer +queues and memory-to-memory devices. In addition, the order of encoded frames +dequeued from the ``CAPTURE`` queue may differ from the order of queuing raw +frames to the ``OUTPUT`` queue, due to properties of the selected coded format, +e.g. frame reordering. + +The client must not assume any direct relationship between ``CAPTURE`` and +``OUTPUT`` buffers and any specific timing of buffers becoming +available to dequeue. Specifically: + +* a buffer queued to ``OUTPUT`` may result in more than one buffer produced on + ``CAPTURE`` (for example, if returning an encoded frame allowed the encoder + to return a frame that preceded it in display, but succeeded it in the decode + order; however, there may be other reasons for this as well), + +* a buffer queued to ``OUTPUT`` may result in a buffer being produced on + ``CAPTURE`` later into encode process, and/or after processing further + ``OUTPUT`` buffers, or be returned out of order, e.g. if display + reordering is used, + +* buffers may become available on the ``CAPTURE`` queue without additional + buffers queued to ``OUTPUT`` (e.g. during drain or ``EOS``), because of the + ``OUTPUT`` buffers queued in the past whose encoding results are only + available at later time, due to specifics of the encoding process, + +* buffers queued to ``OUTPUT`` may not become available to dequeue instantly + after being encoded into a corresponding ``CAPTURE`` buffer, e.g. if the + encoder needs to use the frame as a reference for encoding further frames. + +.. note:: + + To allow matching encoded ``CAPTURE`` buffers with ``OUTPUT`` buffers they + originated from, the client can set the ``timestamp`` field of the + :c:type:`v4l2_buffer` struct when queuing an ``OUTPUT`` buffer. The + ``CAPTURE`` buffer(s), which resulted from encoding that ``OUTPUT`` buffer + will have their ``timestamp`` field set to the same value when dequeued. + + In addition to the straightforward case of one ``OUTPUT`` buffer producing + one ``CAPTURE`` buffer, the following cases are defined: + + * one ``OUTPUT`` buffer generates multiple ``CAPTURE`` buffers: the same + ``OUTPUT`` timestamp will be copied to multiple ``CAPTURE`` buffers, + + * the encoding order differs from the presentation order (i.e. the + ``CAPTURE`` buffers are out-of-order compared to the ``OUTPUT`` buffers): + ``CAPTURE`` timestamps will not retain the order of ``OUTPUT`` timestamps. + +.. note:: + + To let the client distinguish between frame types (keyframes, intermediate + frames; the exact list of types depends on the coded format), the + ``CAPTURE`` buffers will have corresponding flag bits set in their + :c:type:`v4l2_buffer` struct when dequeued. See the documentation of + :c:type:`v4l2_buffer` and each coded pixel format for exact list of flags + and their meanings. + +Should an encoding error occur, it will be reported to the client with the level +of details depending on the encoder capabilities. Specifically: + +* the ``CAPTURE`` buffer (if any) that contains the results of the failed encode + operation will be returned with the ``V4L2_BUF_FLAG_ERROR`` flag set, + +* if the encoder is able to precisely report the ``OUTPUT`` buffer(s) that triggered + the error, such buffer(s) will be returned with the ``V4L2_BUF_FLAG_ERROR`` flag + set. + +.. note:: + + If a ``CAPTURE`` buffer is too small then it is just returned with the + ``V4L2_BUF_FLAG_ERROR`` flag set. More work is needed to detect that this + error occurred because the buffer was too small, and to provide support to + free existing buffers that were too small. + +In case of a fatal failure that does not allow the encoding to continue, any +further operations on corresponding encoder file handle will return the -EIO +error code. The client may close the file handle and open a new one, or +alternatively reinitialize the instance by stopping streaming on both queues, +releasing all buffers and performing the Initialization sequence again. + +Encoding Parameter Changes +========================== + +The client is allowed to use :c:func:`VIDIOC_S_CTRL` to change encoder +parameters at any time. The availability of parameters is encoder-specific +and the client must query the encoder to find the set of available controls. + +The ability to change each parameter during encoding is encoder-specific, as +per the standard semantics of the V4L2 control interface. The client may +attempt to set a control during encoding and if the operation fails with the +-EBUSY error code, the ``CAPTURE`` queue needs to be stopped for the +configuration change to be allowed. To do this, it may follow the `Drain` +sequence to avoid losing the already queued/encoded frames. + +The timing of parameter updates is encoder-specific, as per the standard +semantics of the V4L2 control interface. If the client needs to apply the +parameters exactly at specific frame, using the Request API +(:ref:`media-request-api`) should be considered, if supported by the encoder. + +Drain +===== + +To ensure that all the queued ``OUTPUT`` buffers have been processed and the +related ``CAPTURE`` buffers are given to the client, the client must follow the +drain sequence described below. After the drain sequence ends, the client has +received all encoded frames for all ``OUTPUT`` buffers queued before the +sequence was started. + +1. Begin the drain sequence by issuing :c:func:`VIDIOC_ENCODER_CMD`. + + * **Required fields:** + + ``cmd`` + set to ``V4L2_ENC_CMD_STOP``. + + ``flags`` + set to 0. + + ``pts`` + set to 0. + + .. warning:: + + The sequence can be only initiated if both ``OUTPUT`` and ``CAPTURE`` + queues are streaming. For compatibility reasons, the call to + :c:func:`VIDIOC_ENCODER_CMD` will not fail even if any of the queues is + not streaming, but at the same time it will not initiate the `Drain` + sequence and so the steps described below would not be applicable. + +2. Any ``OUTPUT`` buffers queued by the client before the + :c:func:`VIDIOC_ENCODER_CMD` was issued will be processed and encoded as + normal. The client must continue to handle both queues independently, + similarly to normal encode operation. This includes: + + * queuing and dequeuing ``CAPTURE`` buffers, until a buffer marked with the + ``V4L2_BUF_FLAG_LAST`` flag is dequeued, + + .. warning:: + + The last buffer may be empty (with :c:type:`v4l2_buffer` + ``bytesused`` = 0) and in that case it must be ignored by the client, + as it does not contain an encoded frame. + + .. note:: + + Any attempt to dequeue more ``CAPTURE`` buffers beyond the buffer + marked with ``V4L2_BUF_FLAG_LAST`` will result in a -EPIPE error from + :c:func:`VIDIOC_DQBUF`. + + * dequeuing processed ``OUTPUT`` buffers, until all the buffers queued + before the ``V4L2_ENC_CMD_STOP`` command are dequeued, + + * dequeuing the ``V4L2_EVENT_EOS`` event, if the client subscribes to it. + + .. note:: + + For backwards compatibility, the encoder will signal a ``V4L2_EVENT_EOS`` + event when the last frame has been encoded and all frames are ready to be + dequeued. It is deprecated behavior and the client must not rely on it. + The ``V4L2_BUF_FLAG_LAST`` buffer flag should be used instead. + +3. Once all ``OUTPUT`` buffers queued before the ``V4L2_ENC_CMD_STOP`` call are + dequeued and the last ``CAPTURE`` buffer is dequeued, the encoder is stopped + and it will accept, but not process any newly queued ``OUTPUT`` buffers + until the client issues any of the following operations: + + * ``V4L2_ENC_CMD_START`` - the encoder will not be reset and will resume + operation normally, with all the state from before the drain, + + * a pair of :c:func:`VIDIOC_STREAMOFF` and :c:func:`VIDIOC_STREAMON` on the + ``CAPTURE`` queue - the encoder will be reset (see the `Reset` sequence) + and then resume encoding, + + * a pair of :c:func:`VIDIOC_STREAMOFF` and :c:func:`VIDIOC_STREAMON` on the + ``OUTPUT`` queue - the encoder will resume operation normally, however any + source frames queued to the ``OUTPUT`` queue between ``V4L2_ENC_CMD_STOP`` + and :c:func:`VIDIOC_STREAMOFF` will be discarded. + +.. note:: + + Once the drain sequence is initiated, the client needs to drive it to + completion, as described by the steps above, unless it aborts the process by + issuing :c:func:`VIDIOC_STREAMOFF` on any of the ``OUTPUT`` or ``CAPTURE`` + queues. The client is not allowed to issue ``V4L2_ENC_CMD_START`` or + ``V4L2_ENC_CMD_STOP`` again while the drain sequence is in progress and they + will fail with -EBUSY error code if attempted. + + For reference, handling of various corner cases is described below: + + * In case of no buffer in the ``OUTPUT`` queue at the time the + ``V4L2_ENC_CMD_STOP`` command was issued, the drain sequence completes + immediately and the encoder returns an empty ``CAPTURE`` buffer with the + ``V4L2_BUF_FLAG_LAST`` flag set. + + * In case of no buffer in the ``CAPTURE`` queue at the time the drain + sequence completes, the next time the client queues a ``CAPTURE`` buffer + it is returned at once as an empty buffer with the ``V4L2_BUF_FLAG_LAST`` + flag set. + + * If :c:func:`VIDIOC_STREAMOFF` is called on the ``CAPTURE`` queue in the + middle of the drain sequence, the drain sequence is canceled and all + ``CAPTURE`` buffers are implicitly returned to the client. + + * If :c:func:`VIDIOC_STREAMOFF` is called on the ``OUTPUT`` queue in the + middle of the drain sequence, the drain sequence completes immediately and + next ``CAPTURE`` buffer will be returned empty with the + ``V4L2_BUF_FLAG_LAST`` flag set. + + Although not mandatory, the availability of encoder commands may be queried + using :c:func:`VIDIOC_TRY_ENCODER_CMD`. + +Reset +===== + +The client may want to request the encoder to reinitialize the encoding, so +that the following stream data becomes independent from the stream data +generated before. Depending on the coded format, that may imply that: + +* encoded frames produced after the restart must not reference any frames + produced before the stop, e.g. no long term references for H.264/HEVC, + +* any headers that must be included in a standalone stream must be produced + again, e.g. SPS and PPS for H.264/HEVC. + +This can be achieved by performing the reset sequence. + +1. Perform the `Drain` sequence to ensure all the in-flight encoding finishes + and respective buffers are dequeued. + +2. Stop streaming on the ``CAPTURE`` queue via :c:func:`VIDIOC_STREAMOFF`. This + will return all currently queued ``CAPTURE`` buffers to the client, without + valid frame data. + +3. Start streaming on the ``CAPTURE`` queue via :c:func:`VIDIOC_STREAMON` and + continue with regular encoding sequence. The encoded frames produced into + ``CAPTURE`` buffers from now on will contain a standalone stream that can be + decoded without the need for frames encoded before the reset sequence, + starting at the first ``OUTPUT`` buffer queued after issuing the + `V4L2_ENC_CMD_STOP` of the `Drain` sequence. + +This sequence may be also used to change encoding parameters for encoders +without the ability to change the parameters on the fly. + +Commit Points +============= + +Setting formats and allocating buffers triggers changes in the behavior of the +encoder. + +1. Setting the format on the ``CAPTURE`` queue may change the set of formats + supported/advertised on the ``OUTPUT`` queue. In particular, it also means + that the ``OUTPUT`` format may be reset and the client must not rely on the + previously set format being preserved. + +2. Enumerating formats on the ``OUTPUT`` queue always returns only formats + supported for the current ``CAPTURE`` format. + +3. Setting the format on the ``OUTPUT`` queue does not change the list of + formats available on the ``CAPTURE`` queue. An attempt to set the ``OUTPUT`` + format that is not supported for the currently selected ``CAPTURE`` format + will result in the encoder adjusting the requested ``OUTPUT`` format to a + supported one. + +4. Enumerating formats on the ``CAPTURE`` queue always returns the full set of + supported coded formats, irrespective of the current ``OUTPUT`` format. + +5. While buffers are allocated on any of the ``OUTPUT`` or ``CAPTURE`` queues, + the client must not change the format on the ``CAPTURE`` queue. Drivers will + return the -EBUSY error code for any such format change attempt. + +To summarize, setting formats and allocation must always start with the +``CAPTURE`` queue and the ``CAPTURE`` queue is the master that governs the +set of supported formats for the ``OUTPUT`` queue. diff --git a/Documentation/userspace-api/media/v4l/dev-mem2mem.rst b/Documentation/userspace-api/media/v4l/dev-mem2mem.rst index 9279d87c08a1..40aff9c95267 100644 --- a/Documentation/userspace-api/media/v4l/dev-mem2mem.rst +++ b/Documentation/userspace-api/media/v4l/dev-mem2mem.rst @@ -46,4 +46,5 @@ devices are given in the following sections. :maxdepth: 1 dev-decoder + dev-encoder dev-stateless-decoder diff --git a/Documentation/userspace-api/media/v4l/dev-osd.rst b/Documentation/userspace-api/media/v4l/dev-osd.rst index 67dc46373a91..ad0c156c7898 100644 --- a/Documentation/userspace-api/media/v4l/dev-osd.rst +++ b/Documentation/userspace-api/media/v4l/dev-osd.rst @@ -51,7 +51,7 @@ other information, the physical address of the framebuffer in the ``base`` field of struct :c:type:`v4l2_framebuffer`. The framebuffer device ioctl ``FBIOGET_FSCREENINFO`` returns the same address in the ``smem_start`` field of struct -struct :c:type:`fb_fix_screeninfo`. The ``FBIOGET_FSCREENINFO`` +:c:type:`fb_fix_screeninfo`. The ``FBIOGET_FSCREENINFO`` ioctl and struct :c:type:`fb_fix_screeninfo` are defined in the ``linux/fb.h`` header file. diff --git a/Documentation/userspace-api/media/v4l/dev-sdr.rst b/Documentation/userspace-api/media/v4l/dev-sdr.rst index c9563bca444e..4a80319a53c6 100644 --- a/Documentation/userspace-api/media/v4l/dev-sdr.rst +++ b/Documentation/userspace-api/media/v4l/dev-sdr.rst @@ -78,7 +78,7 @@ field of a struct :c:type:`v4l2_format` to ``V4L2_BUF_TYPE_SDR_CAPTURE`` or ``V4L2_BUF_TYPE_SDR_OUTPUT`` and use the struct :c:type:`v4l2_sdr_format` ``sdr`` member of the ``fmt`` union as needed per the desired operation. Currently -there is two fields, ``pixelformat`` and ``buffersize``, of struct +there are two fields, ``pixelformat`` and ``buffersize``, of struct :c:type:`v4l2_sdr_format` which are used. Content of the ``pixelformat`` is V4L2 FourCC code of the data format. The ``buffersize`` field is maximum buffer size in bytes required for diff --git a/Documentation/userspace-api/media/v4l/hist-v4l2.rst b/Documentation/userspace-api/media/v4l/hist-v4l2.rst index 7913d017cd33..6dcfe6046e33 100644 --- a/Documentation/userspace-api/media/v4l/hist-v4l2.rst +++ b/Documentation/userspace-api/media/v4l/hist-v4l2.rst @@ -43,7 +43,7 @@ transmission arguments. 1998-09-28: Revamped video standard. Made video controls individually enumerable. -1998-10-02: The ``id`` field was removed from struct +1998-10-02: The ``id`` field was removed from struct ``video_standard`` and the color subcarrier fields were renamed. The :ref:`VIDIOC_QUERYSTD` ioctl was renamed to :ref:`VIDIOC_ENUMSTD`, @@ -260,7 +260,7 @@ multiple tuners into account.) 2000-09-18: ``V4L2_BUF_TYPE_VBI`` was added. This may *break compatibility* as the :ref:`VIDIOC_G_FMT <VIDIOC_G_FMT>` and -:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctls may fail now if the struct +:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctls may fail now if the struct ``v4l2_fmt`` ``type`` field does not contain ``V4L2_BUF_TYPE_VBI``. In the documentation of the struct :c:type:`v4l2_vbi_format` ``offset`` field the diff --git a/Documentation/userspace-api/media/v4l/pixfmt-srggb14p.rst b/Documentation/userspace-api/media/v4l/pixfmt-srggb14p.rst index ec1239ada316..e2f5a2b36092 100644 --- a/Documentation/userspace-api/media/v4l/pixfmt-srggb14p.rst +++ b/Documentation/userspace-api/media/v4l/pixfmt-srggb14p.rst @@ -69,37 +69,37 @@ Each cell is one byte. B\ :sub:`00low bits 5--0`\ (bits 5--0) - - R\ :sub:`02low bits 3--0`\ (bits 7--4) + - B\ :sub:`02low bits 3--0`\ (bits 7--4) G\ :sub:`01low bits 5--2`\ (bits 3--0) - G\ :sub:`03low bits 5--0`\ (bits 7--2) - R\ :sub:`02low bits 5--4`\ (bits 1--0) + B\ :sub:`02low bits 5--4`\ (bits 1--0) - .. row 2 - start + 7 - - G\ :sub:`00high` + - G\ :sub:`10high` - - R\ :sub:`01high` + - R\ :sub:`11high` - - G\ :sub:`02high` + - G\ :sub:`12high` - - R\ :sub:`03high` + - R\ :sub:`13high` - - R\ :sub:`01low bits 1--0`\ (bits 7--6) + - R\ :sub:`11low bits 1--0`\ (bits 7--6) - G\ :sub:`00low bits 5--0`\ (bits 5--0) + G\ :sub:`10low bits 5--0`\ (bits 5--0) - - G\ :sub:`02low bits 3--0`\ (bits 7--4) + - G\ :sub:`12low bits 3--0`\ (bits 7--4) - R\ :sub:`01low bits 5--2`\ (bits 3--0) + R\ :sub:`11low bits 5--2`\ (bits 3--0) - - R\ :sub:`03low bits 5--0`\ (bits 7--2) + - R\ :sub:`13low bits 5--0`\ (bits 7--2) - G\ :sub:`02low bits 5--4`\ (bits 1--0) + G\ :sub:`12low bits 5--4`\ (bits 1--0) - .. row 3 @@ -117,13 +117,13 @@ Each cell is one byte. B\ :sub:`20low bits 5--0`\ (bits 5--0) - - R\ :sub:`22low bits 3--0`\ (bits 7--4) + - B\ :sub:`22low bits 3--0`\ (bits 7--4) G\ :sub:`21low bits 5--2`\ (bits 3--0) - G\ :sub:`23low bits 5--0`\ (bits 7--2) - R\ :sub:`22low bits 5--4`\ (bits 1--0) + B\ :sub:`22low bits 5--4`\ (bits 1--0) - .. row 4 diff --git a/Documentation/userspace-api/media/v4l/pixfmt-v4l2.rst b/Documentation/userspace-api/media/v4l/pixfmt-v4l2.rst index 759420a872d6..e0ee2823ab1f 100644 --- a/Documentation/userspace-api/media/v4l/pixfmt-v4l2.rst +++ b/Documentation/userspace-api/media/v4l/pixfmt-v4l2.rst @@ -44,6 +44,11 @@ Single-planar format structure inside the stream, when fed to a stateful mem2mem decoder, the fields may be zero to rely on the decoder to detect the right values. For more details see :ref:`decoder` and format descriptions. + + For compressed formats on the CAPTURE side of a stateful mem2mem + encoder, the fields must be zero, since the coded size is expected to + be calculated internally by the encoder itself, based on the OUTPUT + side. For more details see :ref:`encoder` and format descriptions. * - __u32 - ``pixelformat`` - The pixel format or type of compression, set by the application. diff --git a/Documentation/userspace-api/media/v4l/v4l2.rst b/Documentation/userspace-api/media/v4l/v4l2.rst index ab7c97c39b97..35796c4fbe52 100644 --- a/Documentation/userspace-api/media/v4l/v4l2.rst +++ b/Documentation/userspace-api/media/v4l/v4l2.rst @@ -63,6 +63,7 @@ Authors, in alphabetical order: - Figa, Tomasz <tfiga@chromium.org> - Documented the memory-to-memory decoder interface. + - Documented the memory-to-memory encoder interface. - H Schimek, Michael <mschimek@gmx.at> @@ -75,6 +76,7 @@ Authors, in alphabetical order: - Osciak, Pawel <posciak@chromium.org> - Documented the memory-to-memory decoder interface. + - Documented the memory-to-memory encoder interface. - Osciak, Pawel <pawel@osciak.com> diff --git a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst index e1afc5b504c2..f2a702870fad 100644 --- a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst +++ b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst @@ -121,7 +121,12 @@ than the number requested. other changes, then set ``count`` to 0, ``memory`` to ``V4L2_MEMORY_MMAP`` and ``format.type`` to the buffer type. * - __u32 - - ``reserved``\ [7] + - ``flags`` + - Specifies additional buffer management attributes. + See :ref:`memory-flags`. + + * - __u32 + - ``reserved``\ [6] - A place holder for future extensions. Drivers and applications must set the array to zero. diff --git a/Documentation/userspace-api/media/v4l/vidioc-dqevent.rst b/Documentation/userspace-api/media/v4l/vidioc-dqevent.rst index a9a176d5256d..9412be0c3747 100644 --- a/Documentation/userspace-api/media/v4l/vidioc-dqevent.rst +++ b/Documentation/userspace-api/media/v4l/vidioc-dqevent.rst @@ -260,7 +260,7 @@ call. :ref:`v4l2_queryctrl <v4l2-queryctrl>`. * - __s32 - ``default_value`` - - The default value value of the control. See struct + - The default value of the control. See struct :ref:`v4l2_queryctrl <v4l2-queryctrl>`. diff --git a/Documentation/userspace-api/media/v4l/vidioc-encoder-cmd.rst b/Documentation/userspace-api/media/v4l/vidioc-encoder-cmd.rst index 16269b3b1715..d0eacce5485e 100644 --- a/Documentation/userspace-api/media/v4l/vidioc-encoder-cmd.rst +++ b/Documentation/userspace-api/media/v4l/vidioc-encoder-cmd.rst @@ -51,25 +51,26 @@ To send a command applications must initialize all fields of a struct ``VIDIOC_ENCODER_CMD`` or ``VIDIOC_TRY_ENCODER_CMD`` with a pointer to this structure. -The ``cmd`` field must contain the command code. The ``flags`` field is -currently only used by the STOP command and contains one bit: If the -``V4L2_ENC_CMD_STOP_AT_GOP_END`` flag is set, encoding will continue -until the end of the current *Group Of Pictures*, otherwise it will stop -immediately. +The ``cmd`` field must contain the command code. Some commands use the +``flags`` field for additional information. -A :ref:`read() <func-read>` or :ref:`VIDIOC_STREAMON <VIDIOC_STREAMON>` -call sends an implicit START command to the encoder if it has not been -started yet. After a STOP command, :ref:`read() <func-read>` calls will read +After a STOP command, :ref:`read() <func-read>` calls will read the remaining data buffered by the driver. When the buffer is empty, :ref:`read() <func-read>` will return zero and the next :ref:`read() <func-read>` call will restart the encoder. +A :ref:`read() <func-read>` or :ref:`VIDIOC_STREAMON <VIDIOC_STREAMON>` +call sends an implicit START command to the encoder if it has not been +started yet. Applies to both queues of mem2mem encoders. + A :ref:`close() <func-close>` or :ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` call of a streaming file descriptor sends an implicit immediate STOP to -the encoder, and all buffered data is discarded. +the encoder, and all buffered data is discarded. Applies to both queues of +mem2mem encoders. These ioctls are optional, not all drivers may support them. They were -introduced in Linux 2.6.21. +introduced in Linux 2.6.21. They are, however, mandatory for stateful mem2mem +encoders (as further documented in :ref:`encoder`). .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| @@ -109,21 +110,24 @@ introduced in Linux 2.6.21. - 0 - Start the encoder. When the encoder is already running or paused, this command does nothing. No flags are defined for this command. + + For a device implementing the :ref:`encoder`, once the drain sequence + is initiated with the ``V4L2_ENC_CMD_STOP`` command, it must be driven + to completion before this command can be invoked. Any attempt to + invoke the command while the drain sequence is in progress will trigger + an ``EBUSY`` error code. See :ref:`encoder` for more details. * - ``V4L2_ENC_CMD_STOP`` - 1 - Stop the encoder. When the ``V4L2_ENC_CMD_STOP_AT_GOP_END`` flag is set, encoding will continue until the end of the current *Group Of Pictures*, otherwise encoding will stop immediately. When the - encoder is already stopped, this command does nothing. mem2mem - encoders will send a ``V4L2_EVENT_EOS`` event when the last frame - has been encoded and all frames are ready to be dequeued and will - set the ``V4L2_BUF_FLAG_LAST`` buffer flag on the last buffer of - the capture queue to indicate there will be no new buffers - produced to dequeue. This buffer may be empty, indicated by the - driver setting the ``bytesused`` field to 0. Once the - ``V4L2_BUF_FLAG_LAST`` flag was set, the - :ref:`VIDIOC_DQBUF <VIDIOC_QBUF>` ioctl will not block anymore, - but return an ``EPIPE`` error code. + encoder is already stopped, this command does nothing. + + For a device implementing the :ref:`encoder`, the command will initiate + the drain sequence as documented in :ref:`encoder`. No flags or other + arguments are accepted in this case. Any attempt to invoke the command + again before the sequence completes will trigger an ``EBUSY`` error + code. * - ``V4L2_ENC_CMD_PAUSE`` - 2 - Pause the encoder. When the encoder has not been started yet, the @@ -152,6 +156,8 @@ introduced in Linux 2.6.21. - Stop encoding at the end of the current *Group Of Pictures*, rather than immediately. + Does not apply to :ref:`encoder`. + Return Value ============ @@ -160,6 +166,11 @@ On success 0 is returned, on error -1 and the ``errno`` variable is set appropriately. The generic error codes are described at the :ref:`Generic Error Codes <gen-errors>` chapter. +EBUSY + A drain sequence of a device implementing the :ref:`encoder` is still in + progress. It is not allowed to issue another encoder command until it + completes. + EINVAL The ``cmd`` field is invalid. diff --git a/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst b/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst index a53dd3d7f7e2..05835e04c20b 100644 --- a/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst +++ b/Documentation/userspace-api/media/v4l/vidioc-enum-fmt.rst @@ -167,17 +167,37 @@ the ``mbus_code`` field is handled differently: - The hardware decoder for this compressed bytestream format (aka coded format) is capable of parsing a continuous bytestream. Applications do not need to parse the bytestream themselves to find the boundaries - between frames/fields. This flag can only be used in combination with - the ``V4L2_FMT_FLAG_COMPRESSED`` flag, since this applies to compressed + between frames/fields. + + This flag can only be used in combination with the + ``V4L2_FMT_FLAG_COMPRESSED`` flag, since this applies to compressed formats only. This flag is valid for stateful decoders only. * - ``V4L2_FMT_FLAG_DYN_RESOLUTION`` - 0x0008 - Dynamic resolution switching is supported by the device for this compressed bytestream format (aka coded format). It will notify the user via the event ``V4L2_EVENT_SOURCE_CHANGE`` when changes in the video - parameters are detected. This flag can only be used in combination - with the ``V4L2_FMT_FLAG_COMPRESSED`` flag, since this applies to - compressed formats only. It is also only applies to stateful codecs. + parameters are detected. + + This flag can only be used in combination with the + ``V4L2_FMT_FLAG_COMPRESSED`` flag, since this applies to + compressed formats only. This flag is valid for stateful codecs only. + * - ``V4L2_FMT_FLAG_ENC_CAP_FRAME_INTERVAL`` + - 0x0010 + - The hardware encoder supports setting the ``CAPTURE`` coded frame + interval separately from the ``OUTPUT`` raw frame interval. + Setting the ``OUTPUT`` raw frame interval with :ref:`VIDIOC_S_PARM <VIDIOC_G_PARM>` + also sets the ``CAPTURE`` coded frame interval to the same value. + If this flag is set, then the ``CAPTURE`` coded frame interval can be + set to a different value afterwards. This is typically used for + offline encoding where the ``OUTPUT`` raw frame interval is used as + a hint for reserving hardware encoder resources and the ``CAPTURE`` coded + frame interval is the actual frame rate embedded in the encoded video + stream. + + This flag can only be used in combination with the + ``V4L2_FMT_FLAG_COMPRESSED`` flag, since this applies to + compressed formats only. This flag is valid for stateful encoders only. Return Value diff --git a/Documentation/userspace-api/media/v4l/vidioc-g-parm.rst b/Documentation/userspace-api/media/v4l/vidioc-g-parm.rst index 42e9f6ee7a59..59e02aca164c 100644 --- a/Documentation/userspace-api/media/v4l/vidioc-g-parm.rst +++ b/Documentation/userspace-api/media/v4l/vidioc-g-parm.rst @@ -42,12 +42,13 @@ Arguments Description =========== -The current video standard determines a nominal number of frames per -second. If less than this number of frames is to be captured or output, -applications can request frame skipping or duplicating on the driver -side. This is especially useful when using the :ref:`read() <func-read>` or -:ref:`write() <func-write>`, which are not augmented by timestamps or sequence -counters, and to avoid unnecessary data copying. +Applications can request a different frame interval. The capture or +output device will be reconfigured to support the requested frame +interval if possible. Optionally drivers may choose to skip or +repeat frames to achieve the requested frame interval. + +For stateful encoders (see :ref:`encoder`) this represents the +frame interval that is typically embedded in the encoded video stream. Changing the frame interval shall never change the format. Changing the format, on the other hand, may change the frame interval. @@ -57,7 +58,8 @@ internally by a driver in read/write mode. For implications see the section discussing the :ref:`read() <func-read>` function. To get and set the streaming parameters applications call the -:ref:`VIDIOC_G_PARM <VIDIOC_G_PARM>` and :ref:`VIDIOC_S_PARM <VIDIOC_G_PARM>` ioctl, respectively. They take a +:ref:`VIDIOC_G_PARM <VIDIOC_G_PARM>` and +:ref:`VIDIOC_S_PARM <VIDIOC_G_PARM>` ioctl, respectively. They take a pointer to a struct :c:type:`v4l2_streamparm` which contains a union holding separate parameters for input and output devices. @@ -113,14 +115,21 @@ union holding separate parameters for input and output devices. * - struct :c:type:`v4l2_fract` - ``timeperframe`` - This is the desired period between successive frames captured by - the driver, in seconds. The field is intended to skip frames on - the driver side, saving I/O bandwidth. + the driver, in seconds. + * - :cspan:`2` + + This will configure the speed at which the video source (e.g. a sensor) + generates video frames. If the speed is fixed, then the driver may + choose to skip or repeat frames in order to achieve the requested + frame rate. + + For stateful encoders (see :ref:`encoder`) this represents the + frame interval that is typically embedded in the encoded video stream. Applications store here the desired frame period, drivers return - the actual frame period, which must be greater or equal to the - nominal frame period determined by the current video standard - (struct :c:type:`v4l2_standard` ``frameperiod`` - field). Changing the video standard (also implicitly by switching + the actual frame period. + + Changing the video standard (also implicitly by switching the video input) may reset this parameter to the nominal frame period. To reset manually applications can just set this field to zero. @@ -173,11 +182,15 @@ union holding separate parameters for input and output devices. :ref:`write() <func-write>` mode (in streaming mode timestamps can be used to throttle the output), saving I/O bandwidth. + For stateful encoders (see :ref:`encoder`) this represents the + frame interval that is typically embedded in the encoded video stream + and it provides a hint to the encoder of the speed at which raw + frames are queued up to the encoder. + Applications store here the desired frame period, drivers return - the actual frame period, which must be greater or equal to the - nominal frame period determined by the current video standard - (struct :c:type:`v4l2_standard` ``frameperiod`` - field). Changing the video standard (also implicitly by switching + the actual frame period. + + Changing the video standard (also implicitly by switching the video output) may reset this parameter to the nominal frame period. To reset manually applications can just set this field to zero. @@ -216,8 +229,8 @@ union holding separate parameters for input and output devices. * - ``V4L2_CAP_TIMEPERFRAME`` - 0x1000 - - The frame skipping/repeating controlled by the ``timeperframe`` - field is supported. + - The frame period can be modified by setting the ``timeperframe`` + field. diff --git a/Documentation/userspace-api/media/v4l/vidioc-querycap.rst b/Documentation/userspace-api/media/v4l/vidioc-querycap.rst index 666ac4d42051..90347367ef06 100644 --- a/Documentation/userspace-api/media/v4l/vidioc-querycap.rst +++ b/Documentation/userspace-api/media/v4l/vidioc-querycap.rst @@ -168,11 +168,11 @@ specification the ioctl returns an ``EINVAL`` error code. - The device supports the :ref:`multi-planar API <planar-apis>` through the :ref:`Video Output <output>` interface. * - ``V4L2_CAP_VIDEO_M2M`` - - 0x00004000 + - 0x00008000 - The device supports the single-planar API through the Video Memory-To-Memory interface. * - ``V4L2_CAP_VIDEO_M2M_MPLANE`` - - 0x00008000 + - 0x00004000 - The device supports the :ref:`multi-planar API <planar-apis>` through the Video Memory-To-Memory interface. * - ``V4L2_CAP_VIDEO_OVERLAY`` diff --git a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst index b6d52083707b..75d894d9c36c 100644 --- a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst +++ b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst @@ -112,10 +112,17 @@ aborting or finishing any DMA in progress, an implicit ``V4L2_MEMORY_MMAP`` and ``type`` set to the buffer type. This will free any previously allocated buffers, so this is typically something that will be done at the start of the application. + * - union { + - (anonymous) + * - __u32 + - ``flags`` + - Specifies additional buffer management attributes. + See :ref:`memory-flags`. * - __u32 - ``reserved``\ [1] - - A place holder for future extensions. Drivers and applications - must set the array to zero. + - Kept for backwards compatibility. Use ``flags`` instead. + * - } + - .. tabularcolumns:: |p{6.1cm}|p{2.2cm}|p{8.7cm}| @@ -126,6 +133,7 @@ aborting or finishing any DMA in progress, an implicit .. _V4L2-BUF-CAP-SUPPORTS-REQUESTS: .. _V4L2-BUF-CAP-SUPPORTS-ORPHANED-BUFS: .. _V4L2-BUF-CAP-SUPPORTS-M2M-HOLD-CAPTURE-BUF: +.. _V4L2-BUF-CAP-SUPPORTS-MMAP-CACHE-HINTS: .. cssclass:: longtable @@ -156,6 +164,15 @@ aborting or finishing any DMA in progress, an implicit - Only valid for stateless decoders. If set, then userspace can set the ``V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF`` flag to hold off on returning the capture buffer until the OUTPUT timestamp changes. + * - ``V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS`` + - 0x00000040 + - This capability is set by the driver to indicate that the queue supports + cache and memory management hints. However, it's only valid when the + queue is used for :ref:`memory mapping <mmap>` streaming I/O. See + :ref:`V4L2_FLAG_MEMORY_NON_CONSISTENT <V4L2-FLAG-MEMORY-NON-CONSISTENT>`, + :ref:`V4L2_BUF_FLAG_NO_CACHE_INVALIDATE <V4L2-BUF-FLAG-NO-CACHE-INVALIDATE>` and + :ref:`V4L2_BUF_FLAG_NO_CACHE_CLEAN <V4L2-BUF-FLAG-NO-CACHE-CLEAN>`. + Return Value ============ diff --git a/Documentation/userspace-api/media/videodev2.h.rst.exceptions b/Documentation/userspace-api/media/videodev2.h.rst.exceptions index a625fb90e3a9..ca05e4e126b2 100644 --- a/Documentation/userspace-api/media/videodev2.h.rst.exceptions +++ b/Documentation/userspace-api/media/videodev2.h.rst.exceptions @@ -187,6 +187,7 @@ replace define V4L2_FMT_FLAG_COMPRESSED fmtdesc-flags replace define V4L2_FMT_FLAG_EMULATED fmtdesc-flags replace define V4L2_FMT_FLAG_CONTINUOUS_BYTESTREAM fmtdesc-flags replace define V4L2_FMT_FLAG_DYN_RESOLUTION fmtdesc-flags +replace define V4L2_FMT_FLAG_ENC_CAP_FRAME_INTERVAL fmtdesc-flags # V4L2 timecode types replace define V4L2_TC_TYPE_24FPS timecode-type |