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However, userspace applications (e.g. GStreamer) also rely on this flag to determine whether the decoder will emit an initial V4L2_EVENT_SOURCE_CHANGE event during the Initialization phase, before producing any decoded frames. Add a note in the Initialization section to clarify that decoders setting V4L2_FMT_FLAG_DYN_RESOLUTION will always emit an initial source change event, allowing clients to use this flag to decide whether to wait for the initial resolution signal. Signed-off-by: Ming Qian --- Documentation/userspace-api/media/v4l/dev-decoder.rst | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/Documentation/userspace-api/media/v4l/dev-decoder.rst b/Documentation/userspace-api/media/v4l/dev-decoder.rst index 2beb6ba1b3c2..19c1912804bd 100644 --- a/Documentation/userspace-api/media/v4l/dev-decoder.rst +++ b/Documentation/userspace-api/media/v4l/dev-decoder.rst @@ -361,6 +361,14 @@ Initialization indicated by the decoder sending a ``V4L2_EVENT_SOURCE_CHANGE`` event with ``changes`` set to ``V4L2_EVENT_SRC_CH_RESOLUTION``. + .. note:: + + Decoders that set the ``V4L2_FMT_FLAG_DYN_RESOLUTION`` flag for the + coded format will always emit an initial ``V4L2_EVENT_SOURCE_CHANGE`` + event with ``V4L2_EVENT_SRC_CH_RESOLUTION`` during this phase. Clients + can use this flag to determine whether the decoder will signal the + initial resolution before producing decoded frames. + * It is not an error if the first buffer does not contain enough data for this to occur. Processing of the buffers will continue as long as more data is needed. -- 2.54.0