AC3 in MP4!

[SeeMoreDigital]

Originally Posted by crypto

Yes. To cut the sample, I used QT. Unfortunately, it can only save to MOV. Exporting to MP4 destroys the AC3 track. The original full-length stream however was MP4. Does the sample work for you? If not, I have to find a way to keep the MP4 format.

Interesting... Are you able to cut the sample and remove the AAC audio track. Leaving just the AVC video and AC3 audio streams within .MOV?

[crypto]

Originally Posted by SeeMoreDigital

Interesting... Are you able to cut the sample and remove the AAC audio track. Leaving just the AVC video and AC3 audio streams within .MOV?

Sure, that's simple. If you have QT Pro, open the movie properties, select the stereo track and click delete. Then save the movie.

QT edit functions work ok on this sample, because all tracks are correctly muxed. Have a look at the video track. It has a data size and data rate. As long as that is ok,
iIt is even possible to add an AC3 track in QT.

This is not the case when you mux using mp4box and its derivates. As a result editing in QT is not possible, due to the missing video track data size resp. data rate.

[SeeMoreDigital]

Thanks Crypto,

I've just updated QuickTime Pro to version 7.4.5... And now I can open and edit .MOV files with AC3 audio


Many thanks

[Ranguvar]

Alright, I'm going to beg everyone here

I'd really like to be able to mux MP4's containing both stereo AAC-LC audio (for compatibility with my PS3 and 360), and AC3 5.1. I know HandBrake generates MP4's that can be played in the 360 and PS3 like that, but gdsmux.exe does not work, it creates videos that cannot be played by the 360. And I'd rather not use HandBrake; I prefer to do my video encoding through x264.exe and AviSynth.

So, I'd really love it if somebody could build a working mp4creator with the patch. I have very little experienced in building like this, and the MPEG4IP page warns everyone that Windows builds will most likely crash and burn. So, if a kind soul could perform this task...

[SeeMoreDigital]

Originally Posted by Ranguvar

So, I'd really love it if somebody could build a working mp4creator with the patch. I have very little experienced in building like this, and the MPEG4IP page warns everyone that Windows builds will most likely crash and burn. So, if a kind soul could perform this task...

How about getting involved in the testing of Crypto's new application: -

http://forum.doom9.org/showthread.php?t=138445

[jult]

OK, so I've read this topic and I'm still not certain if it's a good idea to mux ac3 into mp4.
Point is:
I have a lot of AVCHD files from camcorders, they have AC3 audio (256 kbit/s @ 48 kHz) in them, just two channels audio.
It's pretty sad to have to transcode audio again and again, especially if the target is not much different (with regards to bitrate). I currently decode to wav using:
azid --maximize --stereo=stereo --filetype=wav_float
and then encode the wav using:
neroAacEnc -q 0.62
but I'd much rather mux the original .ac3 I demuxed from the .mts file.

Any ideas on that?

[SeeMoreDigital]

Are you re-encoding the AVCHD camcorder captures to a lower bit-rate?

[jult]

Yes, the source is 17 Mbit/s (!) blu-ray level quality. So the video can be downsized for some purposes. Audio is not that good to begin with (from this cam) so I'd like to retain source-quality as much as possible.

I use x264 and avisynth for the video and mp4box to mux it.

[SeeMoreDigital]

I see...

Personally I would hold-off muxing AC3 audio into the .MP4 container until the official (MPEG-4 ISO/IEC) specification for doing so is released... Which should not be much longer.

Until then, I'd recommend muxing AVC video with AC3 audio into either the .TS or .M2TS container, using TSmuxer GUI.


Cheers

[jult]

Originally Posted by SeeMoreDigital

Until then, I'd recommend muxing AVC video with AC3 audio into either the .TS or .M2TS container, using TSmuxer GUI.

Is there a non-GUI way to use TSmuxer? I'm scripting the process, so what I do now is:

for %%a in ("*.h264") do mp4box -add "%%a" -add "%%~na.aac" -fps 25.00 -new "%%~na.mp4"

in a batch-file. I'd like to do similar with TSmuxer. Maybe it's just there, I haven't even looked at TSmuxer yet.

Thanks for the hint!

[crypto]

jult, you can mux AC3 into MOV using Quicktime Pro, but that would not save you from encoding audio to AAC. An AAC fallback track is mandatory. Not all players know how to use the AC3 track. BTW. Which player are you going to use?

[jult]

I'm definitely not ever in my lifetime encoding to mov, sorry.

Players are many, but it needs to be Quicktime compatible.

[crypto]

Originally Posted by jult

I'm definitely not ever in my lifetime encoding to mov, sorry...

Ok, fair enough.

[bond]

ok, the official ac3-in-mp4 specs are publically mentioned (after being mentioned on doom9 of course ):

http://www.mp4ra.org/specs.html

"ETSI TS 102 366 v1.2.1 - Digital Audio Compression (AC-3, Enhanced AC-3) Standard, Annex F"

how to place ac3 in mp4 will be described in annex f to the official ac3 standard

its not yet publically available on the net (at least i didnt find it)

and, word is, nero will switch to this standard as soon as its offical. good thing, nero!

[mediator]

nero will switch to this standard as soon as its offical

@bond: wow! you are _really_ fast

[Ranguvar]

Nice! Now it remains to be seen whether DivX's MKV support or Nero's MP4 support will carry the day... I personally think it will be MKV, which is good IMO because MKV has more features and more formats supported, but we'll see.

[SeeMoreDigital]

Originally Posted by bond

and, word is, nero will switch to this standard as soon as its offical. good thing, nero!

When this happens, hopefully it wont take long for the handful of hardware player manufacturers who already support NeroDigital's AC3 in .MP4 to update their chip-sets firmware...

[mediator]

the wait is over. The updated ETSI TS 102 366 including Annex F is published.

[SeeMoreDigital]

Originally Posted by mediator

the wait is over. The updated ETSI TS 102 366 including Annex F is published.

Hi mediator,

Do you know how quickly Nero will be updating to the revised spec for placing AC3 within .MP4?

Will you be able to provide samples for testing in hardware players?


Cheers

[mediator]

Do you know how quickly Nero will be updating to the revised spec for placing AC3 within .MP4?

For playback, support is going to be released as quick as the release cycle allows (which unfortunately isn't tomorrow ). For Recode, this is currently being figured out.

Will you be able to provide samples for testing in hardware players?

Not right now. But hardware players supporting this don't exist either (right now).