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Old 7th August 2008, 00:13   #1  |  Link
Comatose
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Audio delay in MP4?

I can't figure it out. mp4box's --delay never seems to have any effect. I thought maybe I was doing it wrong, so I used meGUI to do it with an obscene delay like 30000ms, but still no dice.

Using mp4box -info on the muxed mp4 doesn't say anything about a delay and the audio duration is always the same.

What am I doing it wrong? :\
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Old 7th August 2008, 01:24   #2  |  Link
shae
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Maybe players ignore it? If that is indeed the case (no idea), instead try to edit the audio stream and remux.
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Old 7th August 2008, 03:28   #3  |  Link
Comatose
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How would I do that? I need to cut 12ms off it (-12ms delay), but I want to apply the delay/cut it losslessly, or else I would just use Avisynth's DelayAudio ;-;

Also, I don't think players are ignoring it as even mp4box isn't seeing it. I'm probably doing something wrong somehow.
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Old 7th August 2008, 04:18   #4  |  Link
shae
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That depends on the type of audio. I think AAC can be cut with mp4box.

But 12ms is rather short, so it may not be possible to cut at audio frame boundaries (I think a long AAC frame is 1024 samples, a short one is 128, MP3 is 1152, AC3 is 1536), so maybe it's best to find a way to make delay work, assuming it's actually supported.
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Old 7th August 2008, 07:19   #5  |  Link
crypto
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I am not sure, but I think the delay does not change the length of the stream. And BTW: 12 ms delay is not noticeable without messuring equipment.
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Old 7th August 2008, 12:53   #6  |  Link
martino
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Mux it into MKV with a delay. MKVMerge adds silence at the start of the track or cuts off the start depending on the delay, however this does not work for all formats.
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Old 7th August 2008, 13:08   #7  |  Link
Comatose
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Can't really use MKV as I'm aiming to play this on my PS3 D:
Also, *no* delay works, not even 30000ms.
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Old 7th August 2008, 13:22   #8  |  Link
martino
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I meant use muxing audio into MKV to "add/remove" the delay and then demux it and mux into MP4.
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Old 7th August 2008, 13:39   #9  |  Link
poisondeathray
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Try avidemux to shift your audio. It works on .mp4 and .mkv
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Old 15th August 2008, 06:13   #10  |  Link
Comatose
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Oh, thanks, both martino and poisondeathray. I hadn't thought of those
Thanks martino. That worked perfect. This also means I don't have to test the file again on a PS3, since I'm aiming for compatibility

Last edited by Comatose; 15th August 2008 at 07:12.
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