HI Alexandre, On Tue, Nov 24, 2020 at 7:17 PM Alexandre Courbot <acourbot@xxxxxxxxxxxx> wrote: > > Hi Hiro, > > On Fri, Nov 13, 2020 at 6:04 PM Hirokazu Honda <hiroh@xxxxxxxxxxxx> wrote: > > > > Hi, > > > > According to the official v4l2 encoder driver usage description [1], > > v4l2 steatful encoder driver doesn't have a guarantee when frames fed > > to a driver will be returned. > > To make sure all pending frames are output by the driver, an app must > > call VIDIOC_ENCODER_CMD with cmd=V4L2_ENC_CMD_STOP. > > However, it is not mandatory to support the command in the current > > v4l2 stateful encoder API specification. > > An app can check it by VIDIOC_TRY_ENCODER_CMD beforehand. > > My question is when an app has to get all the frames of an encoder > > sequence, how we can achieve this without V4L2_ENC_CMD_STOP support. > > This demand is natural and in fact WebCodecs [2] requires this. > > > > I think there are two options, > > 1.) Ensure that a driver will eventually output frames if it doesn't > > support V4L2_ENC_CMD_STOP. > > 2.) Change V4L2_ENC_CMD_STOP support to be mandatory > > Unless I am missing the part of the spec that says the contrary, > V4L2_ENC_CMD_STOP is part of the encoder specification, and thus is > mandatory. Some older drivers might not have support for it, in such > cases the correct course of action would be to fix them. > I researched the API documents. The statement that the support is mandatory to stateful encoders is added from the latest document v5.9 [1], It states optional in the API document of v4.19 and v5.8. Hence my question is obsolete. [1] https://www.kernel.org/doc/html/v5.9/userspace-api/media/v4l/vidioc-encoder-cmd.html [2] https://www.kernel.org/doc/html/v4.19/media/uapi/v4l/vidioc-encoder-cmd.html [3] https://www.kernel.org/doc/html/v5.8/userspace-api/media/v4l/vidioc-encoder-cmd.html?highlight=v4l2_enc_cmd_stop Best Regards, -Hiro > > > > Any comments are appreciated. > > Thanks so much in advance. > > > > [1] https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/dev-encoder.html#drain > > [2] https://web.dev/webcodecs/ > > > > Sincerely, > > -Hiro
