On Wed, 01. Apr 10:38, Ming Qian wrote:
> when the last frame of capture is dequeueed,
> driver may send this V4L2_EVENT_EOS event,
> If this event is received, then the capture buffers have been flushed and
> avcodec_receive_packet()/avcodec_receive_frame() can return AVERROR_EOF.
> Otherwise, the draining continues until all the capture buffers have been
> dequeued or VIDIOC_DQBUF ioctl returns an EPIPE error.
>
> Some devices may not support V4L2_EVENT_EOS.
> This is logged as a warning message and not treated as a fatal error during
> initialization.
>
> Without this patch imx8qm often hangs at the end of encoding/decoding when
> flushing the capture buffers
>
> Signed-off-by: Ming Qian <ming.q...@nxp.com>
> ---
> libavcodec/v4l2_context.c | 6 ++++++
> libavcodec/v4l2_m2m_dec.c | 8 ++++++++
> libavcodec/v4l2_m2m_enc.c | 19 +++++++++++++++++++
> 3 files changed, 33 insertions(+)
>
> diff --git a/libavcodec/v4l2_context.c b/libavcodec/v4l2_context.c
> index 8110bbb555..6b1f65fe4c 100644
> --- a/libavcodec/v4l2_context.c
> +++ b/libavcodec/v4l2_context.c
> @@ -154,6 +154,7 @@ static inline void v4l2_save_to_context(V4L2Context* ctx,
> struct v4l2_format_upd
> }
>
> /**
> + * handle resolution change event and end of stream event
> * returns 1 if reinit was successful, negative if it failed
> * returns 0 if reinit was not executed
> */
> @@ -171,6 +172,11 @@ static int v4l2_handle_event(V4L2Context *ctx)
> return 0;
> }
>
> + if (evt.type == V4L2_EVENT_EOS) {
> + ctx->done = 1;
> + return 0;
> + }
> +
> if (evt.type != V4L2_EVENT_SOURCE_CHANGE)
> return 0;
>
> diff --git a/libavcodec/v4l2_m2m_dec.c b/libavcodec/v4l2_m2m_dec.c
> index d666edffe4..9989649784 100644
> --- a/libavcodec/v4l2_m2m_dec.c
> +++ b/libavcodec/v4l2_m2m_dec.c
> @@ -123,6 +123,14 @@ static int v4l2_prepare_decoder(V4L2m2mContext *s)
> }
> }
>
> + memset(&sub, 0, sizeof(sub));
> + sub.type = V4L2_EVENT_EOS;
> + ret = ioctl(s->fd, VIDIOC_SUBSCRIBE_EVENT, &sub);
> + if (ret < 0) {
> + av_log(s->avctx, AV_LOG_WARNING,
> + "the v4l2 driver does not support end of stream
> VIDIOC_SUBSCRIBE_EVENT\n");
> + }
> +
> return 0;
> }
>
> diff --git a/libavcodec/v4l2_m2m_enc.c b/libavcodec/v4l2_m2m_enc.c
> index 84de63ec9d..78cf9ba47a 100644
> --- a/libavcodec/v4l2_m2m_enc.c
> +++ b/libavcodec/v4l2_m2m_enc.c
> @@ -155,6 +155,23 @@ static int v4l2_check_b_frame_support(V4L2m2mContext *s)
> return AVERROR_PATCHWELCOME;
> }
>
> +static int v4l2_subscribe_eos_event(V4L2m2mContext *s)
> +{
> + struct v4l2_event_subscription sub;
> + int ret;
> +
> + memset(&sub, 0, sizeof(sub));
> + sub.type = V4L2_EVENT_EOS;
> + ret = ioctl(s->fd, VIDIOC_SUBSCRIBE_EVENT, &sub);
> + if (ret < 0) {
> + av_log(s->avctx, AV_LOG_WARNING,
> + "the v4l2 driver does not support end of stream
> VIDIOC_SUBSCRIBE_EVENT\n");
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> static int v4l2_prepare_encoder(V4L2m2mContext *s)
> {
> AVCodecContext *avctx = s->avctx;
> @@ -164,6 +181,8 @@ static int v4l2_prepare_encoder(V4L2m2mContext *s)
> /**
> * requirements
> */
> + v4l2_subscribe_eos_event(s);
> +
> ret = v4l2_check_b_frame_support(s);
> if (ret)
> return ret;
> --
> 2.26.0
>
lgtm
Tested on RPi4 and Odroid XU4.
Thanks,
--
Andriy
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