[FFmpeg-user] Problems with AC3

[Paul B Mahol]

On Tue, Sep 14, 2021 at 4:52 PM Richard Kimberly Heck <rikiheck at lyx.org>
wrote:

> Hi, all,
>
> I've recently started experiencing problems when convering files with
> AC3 video. Basically, I end up with no sound. Here's an example. This
> file reports as:
>
> Input #0, mpeg, from 'vobfile.vob':
>    Duration: 01:26:05.22, start: 0.233567, bitrate: 4943 kb/s
>    Stream #0:0[0x1e0]: Video: mpeg2video (Main), yuv420p(tv, smpte170m,
> progressive), 720x480 [SAR 32:27 DAR 16:9], 29.97 fps, 59.94 tbr, 90k
> tbn, 59.94 tbc
>      Side data:
>        cpb: bitrate max/min/avg: 9800000/0/0 buffer size: 1835008
> vbv_delay: N/A
>    Stream #0:1[0x80]: Audio: ac3, 48000 Hz, 5.1(side), fltp, 448 kb/s
>
> I try to convert it to mp4 with:
>
> ffmpeg -i vobfile.vob -f mp4 -b:v 2500k -vcodec libx264 -b:a 192k
> -aspect 16:9 -sn -y vobfile.mp4
>
> and I get a file with no sound or (in other cases) only with very choppy
> sound that is unintelligible. It's only with AC3 input that this seems
> to be happening.
>
> Are there other options I can try?
>

Make sure that ac3 you want to transcode  is playing/decoding fine in
ffplay first.

>
> Thanks,
> Riki
>
>
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