media/v4l/dev-encoder.rst

26 2. The meaning of words "must", "may", "should", etc. is as per `RFC
31 4. :c:func:`VIDIOC_G_EXT_CTRLS` and :c:func:`VIDIOC_S_EXT_CTRLS` may be used
35 5. Single-planar API (see :ref:`planar-apis`) and applicable structures may be
89    client may call :c:func:`VIDIOC_ENUM_FMT` on ``CAPTURE``.
94 2. To enumerate the set of supported raw formats, the client may call
104 3. The client may use :c:func:`VIDIOC_ENUM_FRAMESIZES` to detect supported
117 4. The client may use :c:func:`VIDIOC_ENUM_FRAMEINTERVALS` to detect supported
138    ``CAPTURE``, if applicable, may be queried using their respective controls
141 6. Any additional encoder capabilities may be discovered by querying
158          desired size of ``CAPTURE`` buffers; the encoder may adjust it to
178       Changing the ``CAPTURE`` format may change the currently set ``OUTPUT``
222          may be adjusted to match encoder minimums, maximums and alignment
246 	 the desired frame interval; the encoder may adjust it to
260       ``OUTPUT`` queue is just a hint, the application may provide raw
297 	 the desired coded frame interval; the encoder may adjust it to
340          rectangle and may be subject to adjustment to match codec and
365             e.g.  the common 1920x1080 resolution may require the source
372       The encoder may adjust the crop/compose rectangles to the nearest
377    :c:func:`VIDIOC_REQBUFS`. This may be performed in any order.
398       The actual number of allocated buffers may differ from the ``count``
405       depth), the client may query the ``V4L2_CID_MIN_BUFFERS_FOR_OUTPUT``
430    :c:func:`VIDIOC_STREAMON`. This may be performed in any order. The actual
438    on the coded format, but may include the following implications:
456 format and may be affected by codec-specific extended controls, as stated
461 dequeued from the ``CAPTURE`` queue may differ from the order of queuing raw
469 * a buffer queued to ``OUTPUT`` may result in more than one buffer produced on
472   order; however, there may be other reasons for this as well),
474 * a buffer queued to ``OUTPUT`` may result in a buffer being produced on
479 * buffers may become available on the ``CAPTURE`` queue without additional
484 * buffers queued to ``OUTPUT`` may not become available to dequeue instantly
534 error code. The client may close the file handle and open a new one, or
546 per the standard semantics of the V4L2 control interface. The client may
549 configuration change to be allowed. To do this, it may follow the `Drain`
597         The last buffer may be empty (with :c:type:`v4l2_buffer`
666    Although not mandatory, the availability of encoder commands may be queried
672 The client may want to request the encoder to reinitialize the encoding, so
674 generated before. Depending on the coded format, that may imply that:
698 This sequence may be also used to change encoding parameters for encoders
707 1. Setting the format on the ``CAPTURE`` queue may change the set of formats
709    that the ``OUTPUT`` format may be reset and the client must not rely on the