[FFmpeg-devel] [PATCH] examples/decode_video: flush parser to fix missing frame

[Zhao Zhili]

> On Sep 9, 2020, at 1:55 PM, Guangxin Xu <oddstone at gmail.com> wrote:
> 
> 
> 
> On Tue, Aug 18, 2020 at 8:05 PM <quinkblack at foxmail.com <mailto:quinkblack at foxmail.com>> wrote:
> From: Zhao Zhili <quinkblack at foxmail.com <mailto:quinkblack at foxmail.com>>
> 
> To reproduce, run decode_video with a single frame sample. No frame
> was decoded before the patch.
> ---
>  doc/examples/decode_video.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/doc/examples/decode_video.c b/doc/examples/decode_video.c
> index 169188a4b9..ba753c6dc1 100644
> --- a/doc/examples/decode_video.c
> +++ b/doc/examples/decode_video.c
> @@ -92,6 +92,7 @@ int main(int argc, char **argv)
>      uint8_t *data;
>      size_t   data_size;
>      int ret;
> +    int eof;
>      AVPacket *pkt;
> 
>      if (argc <= 2) {
> @@ -150,15 +151,14 @@ int main(int argc, char **argv)
>          exit(1);
>      }
> 
> -    while (!feof(f)) {
> +    do {
>          /* read raw data from the input file */
>          data_size = fread(inbuf, 1, INBUF_SIZE, f);
> -        if (!data_size)
> -            break;
> +        eof = !data_size;
> 
>          /* use the parser to split the data into frames */
>          data = inbuf;
> -        while (data_size > 0) {
> +        while (data_size > 0 || eof) {
>              ret = av_parser_parse2(parser, c, &pkt->data, &pkt->size,
>                                     data, data_size, AV_NOPTS_VALUE, AV_NOPTS_VALUE, 0);
>              if (ret < 0) {
> @@ -170,8 +170,10 @@ int main(int argc, char **argv)
> 
>              if (pkt->size)
>                  decode(c, frame, pkt, outfilename);
> +            if (eof)
> +                break;
> what if the parser cached more than one frame at the eof?

Good point. The internal loop should break only if (pkt->size == 0 && eof).

The updated patch:
http://ffmpeg.org/pipermail/ffmpeg-devel/2020-September/270251.html

>          }
> -    }
> +    } while (!eof);
> 
>      /* flush the decoder */
>      decode(c, frame, NULL, outfilename);
> -- 
> 2.28.0
> 
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org <mailto:ffmpeg-devel at ffmpeg.org>
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel <https://ffmpeg.org/mailman/listinfo/ffmpeg-devel>
> 
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request at ffmpeg.org <mailto:ffmpeg-devel-request at ffmpeg.org> with subject "unsubscribe".