[FFmpeg-user] AAC track copy problem in mp4

Petr Tresnak peter.cherry at quick.cz
Mon Feb 9 09:29:03 CET 2015


Do you think FFmpeg is not able to demux/remux Panasonic GH4 (or LX100) 4K video MP4 properly?
I would prefer one tool solution...
Peter


> Date: Fri, 6 Feb 2015 14:25:46 -0500
> From: mediastream at gmail.com
> To: ffmpeg-user at ffmpeg.org
> Subject: Re: [FFmpeg-user] AAC track copy problem in mp4
> 
> Maybe try demuxing it with MP4Box, resize with FFmpeg, then remux with
> MP4Box?
> http://gpac.wp.mines-telecom.fr/downloads/gpac-nightly-builds/
> 
> 
> On Fri, Feb 6, 2015 at 10:37 AM, Petr Tresnak <peter.cherry at quick.cz> wrote:
> 
> > Hi all,
> > I downscale the following 4k to 1080 using ffmpeg -i 4k.mp4 -vf
> > scale=1920:1080 -c:v libx264 -preset fast -crf 18 -c:a copy output.mp4"
> >
> > Duration: 00:00:10.56, start: 0.080000, bitrate: 95904 kb/
> > Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuvj420p(pc,
> > bt709), 3840x2160 [SAR 1:1 DAR 16:9], 95655 kb/s, 25 fps
> > Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp,
> > 124 kb/s (default)
> >
> > But there is a problem with proper copy of audio track:
> >
> > [mp4 @ 05e30860] track 1: codec frame size is not set
> > [mp4 @ 05e30860] Packet with invalid duration -1024 in stream 1
> >
> > In trans-coded video file there is a small difference in audio afterwards
> > (AAC vs AAC LC, bitrate 124 vs 125):
> > Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo,
> > fltp, 125 kb/s (default)
> >
> > Can you help how to force ffmpeg to copy audio track?
> > Thanks
> > Peter
> >
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> > ffmpeg-user at ffmpeg.org
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> >
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