[FFmpeg-devel] [PATCH 22/36] fftools/ffmpeg: drop an obsolete hack

[Wang, Fei W]

On Wed, 2023-05-17 at 12:20 +0200, Anton Khirnov wrote:
> This special handling for decoder flushing has not been needed since
> af1761f7b5, as the filtergraph actually is drained after that commit.
> ---
>  fftools/ffmpeg.c | 11 -----------
>  1 file changed, 11 deletions(-)
> 
> diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
> index 9d554e2fb0..49313edebc 100644
> --- a/fftools/ffmpeg.c
> +++ b/fftools/ffmpeg.c
> @@ -1418,17 +1418,6 @@ static int process_input_packet(InputStream
> *ist, const AVPacket *pkt, int no_eo
>          if (!got_output)
>              break;
>  
> -        // During draining, we might get multiple output frames in
> this loop.
> -        // ffmpeg.c does not drain the filter chain on configuration
> changes,
> -        // which means if we send multiple frames at once to the
> filters, and
> -        // one of those frames changes configuration, the buffered
> frames will
> -        // be lost. This can upset certain FATE tests.
> -        // Decode only 1 frame per call on EOF to appease these FATE
> tests.
> -        // The ideal solution would be to rewrite decoding to use
> the new
> -        // decoding API in a better way.
> -        if (!pkt)
> -            break;
> -
Hi,

This will drain out HW filter's output frames if it uses fixed number
which is less than frame threads of decoder. Decoded frame keep sending
to filter in flushing while filtered frames can't be reaped. An example
cmd:

ffmpeg -threads 20 -v verbose -init_hw_device
vaapi=hw:/dev/dri/renderD128 -hwaccel_output_format vaapi -hwaccel
vaapi -i avc.mp4 -vf 'scale_va
api=w=720:h=480' -f null -

...
Error while filtering: Cannot allocate memory
Failed to inject frame into filter network: Cannot allocate memory
Error while processing the decoded data for stream #0:0

Thanks

>          repeating = 1;
>      }
>