Re: [FFmpeg-devel] [PATCH v5 3/7] avcodec/v4l2_context: add v4l2_start_decode

[Andriy Gelman <andriy.gelman@gmail.com>]

On Tue, 04. Jan 17:08, Ming Qian wrote:
> on dynamic resolution change,
> The decoding process must be resumed with either a pair of calls to
> VIDIOC_STREAMOFF() and VIDIOC_STREAMON() on the CAPTURE queue, or a call
> to VIDIOC_DECODER_CMD() with the V4L2_DEC_CMD_START command.
> 

For the patch title, I think something like the following would be better:
avcodec/v4l2_context: send start decode command after dynamic resolution change
event

I'll add that this fixes decoding of 
https://streams.videolan.org/ffmpeg/incoming/720p60.mp4 on RPi4.

> Signed-off-by: Ming Qian <ming.qian@nxp.com>
> ---
>  libavcodec/v4l2_context.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/libavcodec/v4l2_context.c b/libavcodec/v4l2_context.c
> index dda5157698c3..a181f884d2a6 100644
> --- a/libavcodec/v4l2_context.c
> +++ b/libavcodec/v4l2_context.c
> @@ -153,6 +153,21 @@ static inline void v4l2_save_to_context(V4L2Context* ctx, struct v4l2_format_upd
>      }
>  }
>  
> +static int v4l2_start_decode(V4L2Context *ctx)
> +{
> +    struct v4l2_decoder_cmd cmd = {
> +        .cmd = V4L2_DEC_CMD_START,
> +        .flags = 0,
> +    };
> +    int ret;
> +
> +    ret = ioctl(ctx_to_m2mctx(ctx)->fd, VIDIOC_DECODER_CMD, &cmd);
> +    if (ret)
> +        return AVERROR(errno);
> +
> +    return 0;
> +}
> +
>  /**
>   * handle resolution change event and end of stream event
>   * returns 1 if reinit was successful, negative if it failed
> @@ -190,6 +205,9 @@ static int v4l2_handle_event(V4L2Context *ctx)
>          s->capture.height = v4l2_get_height(&cap_fmt);
>          s->capture.width = v4l2_get_width(&cap_fmt);
>          s->capture.sample_aspect_ratio = v4l2_get_sar(&s->capture);
> +    } else {
> +        v4l2_start_decode(ctx);
> +        return 0;
>      }
>  
>      if (reinit)

lgtm otherwise.

Thanks
-- 
Andriy
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