[FFmpeg-devel] doc/examples/demuxing.c is broken

[Stefano Sabatini]

On date Tuesday 2013-07-09 23:21:11 +0200, wm4 encoded:
> There are at least two problems with it wrt. audio: it doesn't attempt
> to decode a packet multiple times, and it doesn't handle planar formats.
> 
> Here's a patch to fix the first issue. I'm not sure whether the output
> is fine, because I don't feel like researching how it writes planar
> audio to a file.

> diff --git a/doc/examples/demuxing.c b/doc/examples/demuxing.c

please send git format patch

> index 8a1b69b..774f99c 100644
> --- a/doc/examples/demuxing.c
> +++ b/doc/examples/demuxing.c
> @@ -60,6 +60,7 @@ static int audio_frame_count = 0;
>  static int decode_packet(int *got_frame, int cached)
>  {
>      int ret = 0;
> +    int decoded = 0;
>  
>      if (pkt.stream_index == video_stream_idx) {
>          /* decode video frame */
> @@ -68,6 +69,7 @@ static int decode_packet(int *got_frame, int cached)
>              fprintf(stderr, "Error decoding video frame\n");
>              return ret;
>          }
> +        decoded = pkt.size;
>  
>          if (*got_frame) {
>              printf("video_frame%s n:%d coded_n:%d pts:%s\n",
> @@ -91,6 +93,7 @@ static int decode_packet(int *got_frame, int cached)
>              fprintf(stderr, "Error decoding audio frame\n");
>              return ret;
>          }
> +        decoded = ret;
>  
>          if (*got_frame) {
>              printf("audio_frame%s n:%d nb_samples:%d pts:%s\n",
> @@ -121,6 +124,7 @@ static int decode_packet(int *got_frame, int cached)
>          }
>      }
>  

> +    ret = FFMIN(decoded, pkt.size);
>      return ret;

return decoded;
?

>  }
>  
> @@ -293,7 +297,15 @@ int main (int argc, char **argv)
>  
>      /* read frames from the file */
>      while (av_read_frame(fmt_ctx, &pkt) >= 0) {
> -        decode_packet(&got_frame, 0);
> +        AVPacket orig = pkt;
> +        do {
> +            ret = decode_packet(&got_frame, 0);
> +            if (ret < 0)
> +                break;
> +            pkt.data += ret;
> +            pkt.size -= ret;
> +        } while (pkt.size > 0);
> +        pkt = orig;
>          av_free_packet(&pkt);

Slightly simpler:
AVPacket orig_pkt = pkt;
do {
...
} while (pkt.size > 0)

av_free_packet(&orig_pkt);
-- 
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