[FFmpeg-user] Creating video with xfade takes 27 GB of memory

[Paul B Mahol]

On Sun, May 28, 2023 at 12:22 PM Cecil Westerhof via ffmpeg-user <
ffmpeg-user at ffmpeg.org> wrote:

> Reindl Harald <h.reindl at thelounge.net> writes:
>
> > Am 25.05.23 um 08:16 schrieb Cecil Westerhof via ffmpeg-user:
> >> Paul B Mahol <onemda at gmail.com> writes:
> >>
> >>> Use master FFmpeg version, where memory requirements for this filter
> >>> have been drastically reduced.
> >> I installed the version from here:
> >>      https://johnvansickle.com/ffmpeg/
> >
> > git master: built on 20230313
> > we have 20230525
> >
> >> Or should I be trying (I am on Debian):
> >> https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu
> >
> > that's the point of "use master"
>
> That makes it even worse. Then I get:
>     [vost#0:0/libx264 @ 0x565136728c00] Too many packets buffered for
> output stream 0:0.
>     [vost#0:0/libx264 @ 0x565136728c00] Error submitting a packet to the
> muxer
>     [vost#0:0/libx264 @ 0x565136728c00] Too many packets buffered for
> output stream 0:0.
>     [vost#0:0/libx264 @ 0x565136728c00] Error submitting a packet to the
> muxer
>
> and it seems to go on forever.
>
> I also found it a bit strange, because I do it with a lot of different
> videos and only one went wrong.
>
> It seems I have found a bug in ffmpeg.
> For the first input-file I used:
>     -ss 48 -t 4
>
> But when looking in the log I see:
>     Input #0, matroska,webm, from 'langeLijn1c.mkv':
>       Metadata:
>         ENCODER         : Lavf60.3.100
>       Duration: 00:00:52.05, start: 0.000000, bitrate: 20470 kb/s
>       Stream #0:0: Video: h264 (High), yuv420p(progressive), 1920x1080
> [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 1k tbn
>         Metadata:
>           DURATION        : 00:00:52.047000000
>       Stream #0:1: Audio: mp3, 48000 Hz, stereo, fltp, 117 kb/s
>         Metadata:
>           DURATION        : 00:00:51.768000000
>
> So the video is long enough, but the audio is to short.
> Personally I would say that instead of going berserk when the input is
> to short an error should be generated.
> When changing the timing to:
>     -ss 47 -t 4
>
> Everything went fine.
>

Ah, audio gets out of sync of video because acrossfade buffers audio for
exact duration as specified and if that does not match anymore with video
it will break,
better error out like above than consuming that much memory.


>
> --
> Cecil Westerhof
> Senior Software Engineer
> LinkedIn: http://www.linkedin.com/in/cecilwesterhof
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