Muxing Audio into MP4

[mars2010]

I have a video(.264) and an audio file(.aac) to mux.

I use MP4Box(sometimes Yamb) to mux them.
Most of the time there seems no synchronization problem in muxing, but I am not sure there will be no problem everytime.

Is there any way to put timestamps in the AAC file before or after muxing?

I have little experience in video/audio processing
so please advise me.

Thank you.

[kypec]

AAC audio has no such thing as timestamps. Timecodes are used only in certain VariableFrameRate video streams.
I'd suggest to encode always with x264 output set to MKV, maybe MP4 if needed but not raw H.264 as raw AVC stream can't retain
original timecodes from your source footage.
Also make sure to use MP4Box versions that do not suffer from A/V sync problems, for example golgol's Windows builds (http://komisar.gin.by/tools/).
I never had any problems with those - but I also never deal with VFR content anyway ;)

[mars2010]

I thought that I should use the timestamps always to sync
audio and video. but it was for VFR only, Thanks.

[SeeMoreDigital]

How about giving DVBPortal's MP4Muxer (http://www.dvbportal.de/projects/mp4muxer/) a try...

It based around "mp4creator" 1.6.1d instead of "mp4box".


Cheers

[b66pak]

is outdated and not developed anymore (both cli and gui)...also is not QT friendly anymore...
_

[SeeMoreDigital]

also is not QT friendly anymore...In what way?

[b66pak]

read this (http://forum.doom9.org/showthread.php?p=1375306#post1375306)...
_

[SeeMoreDigital]

read this (http://forum.doom9.org/showthread.php?p=1375306#post1375306)...
_
I have noticed this too. Which is why I'm still using Quiktime Player (Pro) v7.6.2.

As far as I'm aware, the "double runtime" bug does not happen with the newer Mac versions of Quicktime player...

EDIT: That said, I don't think mars2010 wants to generate .MOV conformat muxes.

[mars2010]

Thanks but I don't have much idea on QuickTime and .mov file.

Anyhow there is one curiousity in my mind.

If the frame rate of the .264 video is whatever
30, 29.97, or 25 FPS,
I can get a synchronized output with general AAC file.
Is that right?
(--> if it's synchronized at the starting position,
it will also be at the ending position)

If I can't get a synchronized output like that
I should consider using another software rather than
MP4Box.

[nixo]

Thanks but I don't have much idea on QuickTime and .mov file.

Anyhow there is one curiousity in my mind.

If the frame rate of the .264 video is whatever
30, 29.97, or 25 FPS,
I can get a synchronized output with general AAC file.
Is that right?
(--> if it's synchronized at the starting position,
it will also be at the ending position)


Sure. However, do note that mp4box assumes 25fps for raw input. If your video is *not* 25fps you need to specify fps.

--
Nikolaj

[yetanotherid]

I've found frame rates can vary by a tiny fraction, which might have one program seeing a 23.976 video (for example) as 23.975 and I've definitely converted video where the frame rate was reported as 23.976 but when I muxed the output without specifying a frame rate the audio sync wass slightly different than it was when I specified a 23.976 frame rate.

So.... if there's an audio sync problem I first try specifying the correct frame rate and then try changing it a little. Although I tend to avoid MP4s as much as possible because they're so painfully slow compared to using MKVToolnix and MKVs.

[SeeMoreDigital]

If I can't get a synchronized output like that I should consider using another software rather than MP4Box.As I mentioned before. How about giving DVBPortal's MP4Muxer (http://www.dvbportal.de/projects/mp4muxer/) a try...

It based around "mp4creator" not "mp4box".