Remux problems, ac3 file not being accepted

[djhep]

I cant get any of my mux tools to accept my ac3 stream. I demuxed a video ts folder to change the aspect ratio with pulldownx. But all the kings horses and all the kings men couldnt put my ac3 and m2v together again,

More details:https://www.videohelp.com/forum/viewtopic.php?t=224542

[djhep]

Ive done some searches and all i've been able to find is something about the ac3 file possibly being incomplete. The post says there is a fix that may cause synch problems but does not go into detail. I've tried different apps to rip then mux the streams but get the same error messages about the ac3 file.

[TugBoat]

So have you tried converting the ac3 back to a wav and see what you get? If the durations are the same, you could then use ffmpegX to convert the wav back to ac3. A good ac3 this time. Bad aspect, bad ac3, how did you make the original DVD

[djhep]

With DiscomVOBulator a long time ago. First DVD came out fine for some reason when it split Disco flagged the second DVD with the wrong aspect ratio. If the ac3 file is bad how come the video TS folder plays and sounds fine? (Except for the aspest ratio, of course.)

[TugBoat]

If the ac3 file is bad how come the video TS folder plays and sounds fine? (Except for the aspect ratio, of course.)

Because a player is less strict than a Muxer. I've had discs that would play but fail to copy. The Mac couldn't copy the data because of damage but it played none the less. Another reason is;

I've tried different apps to rip then mux the streams but get the same error messages about the ac3 file.

Second opinions are helpful 8) So did you try to remix the ac3? At this point that's the only hope.

[djhep]

Thanks for all the help, Tugboat.

Could you please give me some details on how to do this stuff?

So have you tried converting the ac3 back to a wav and see what you get? If the durations are the same, you could then use ffmpegX to convert the wav back to ac3.

So did you try to remix the ac3? At this point that's the only hope.

[TugBoat]

There are numerous tools to convert an ac3 to wav;
a52decX 0.24
bd4go
mAC3dec
ffmpegX
Unfortunately, not a single one will give the duration of the ac3. A.Pack does, but A.Pack is part of DVDSP. So, I'd say to look at the 'Time Remaining' in DVD Player to get an idea of the DVD's duration. Once you convert the ac3 to wav, open the wav in QT and check it's duration. It should be close. If the wav looks close, open it in ffmpegX and choose the preset 'audio file to ac3', specify the bitrate, Hz, and choose stereo or 5:1. Encode. Done.

mAC3dec offers the option to 'fix' the ac3, it takes forever and usually doesn't work. It is an option though.

[djhep]

HOW 'BOUT THEM PISTONS!


I've used mac3dec before but never noticed the "fix" option under decode. Not expecting it to work i tried it. It said it fixed two frames. The duration did not change after "fixing" it. It's one second shorter than the m2v file. Ffmpegx finally accepted the ac3 file and produced a video ts folder that is slighty out of synch. I think i can live with it but is there a better muxer or a way to synch the already muxed file? Thanks again.

[TugBoat]

Glad to hear it finally worked.
DVDSP has a pretty good muxer, at a pretty good price. If you want to try to synch the audio you have to take the ac3 back to a wav and work with the wav. I have the QT MPEG2 component so I can open the m2v, 'add scaled' the wav, and see if the audio is late or early, where the problem is (at the beginning, end, or everywhere). I usually use Peak to 'add silence' or cut about a tenth of a second from either the end or beginning. It's sorta trial and error and takes time, but it works. You can use QT instead of Peak if you must. Then convert the wav back to ac3 and mux. Lottsa fun :P

[djhep]

Thank you for all your help, Tugboat. This is such a great website. I have learned SO MUCH about working with video on my computor since i stumbled accross vcdhelp.com early last year.

There are numerous tools to convert an ac3 to wav;
a52decX 0.24
bd4go
mAC3dec
ffmpegX
Unfortunately, not a single one will give the duration of the ac3.

After I loaded the ac3 file into mac3dec I clicked on it to highlight it and it showed the duration and that it was 5.1 channel.

I'm not going to mess with it any more. The synch problem is only in the second half and gets better towards the end.