extracting and converting ac3

[engel]

I have a movie (DivX LM/ac3) which is 1.4 GB large. I would like to recompress it down to 700 MB - you guess why.

First I only could watch the video, no sound. VirtualDub1.4.9 and NanDub 1.0rc2 both reported a "tag2000" error on audio. Some kind person of this forum pointed me towards ac3 and after downloading
a couple of codecs I got the thing working, sound and picture.

I would assume from this that the file is ok.

Extracting video from that file results in about 1GB, playing ok and ready to be recompressed.

Extracting the audio both with nandub and with virtualdub1.3c-ac3 results in a file about .4 GB large, i.e. the "remainder" but I can't
listen to this file, since it won't play. I am not quite sure at this point whether this is normal or not, in any case I am not sure whether it got extracted ok from the original file.

Trying to convert this into mp3 with besweet1.2rc2/guiv0.6b15 or
heada3che0.22b does not work either: besweet does not run properly on
my computer (w2k/sp2 - Sony laptop) and headache crashes saying something like "either your ac3 file is corrupt or frames are missing".

At this point, I am afraid, I do not have any more ideas what to do.

Suggestions are highly welcome! Thanks a lot in advance.

Siggi


PS: Upon saving the .wav with either vd or nd, there was no option like "save ac3". But I chose "all files" and changed the extension into ".ac3" - I faintly remember somebody claiming this would be important. Apparently it does not help in this case.
:(

[DSPguru]

Originally posted by engel
Trying to convert this into mp3 with besweet1.2rc2/guiv0.6b15 or
heada3che0.22b does not work either: besweet does not run properly on
my computer (w2k/sp2 - Sony laptop) if you want help with this issue, you would need to pay attention to this (http://forum.doom9.org/showthread.php?s=&threadid=15738) :
a. make sure you're using the latest release of BeSweet. (i can't support old versions).
b. feel free to report bugs for beta releases, unLess i already released a newer stable release.
c. please state the command line was used. (if you use the GUI - click the "Copy command to clipboard" button).
d. try to create a logfile and paste it in your thread.
e. if BeSweet raised gpf (crashed), please state the process that raised the gpf (for instance : BeSweet.exe , ssrc.dll , azid.dll,...).
f. if it could be relevant - point out the operating system/computer system was used.

Best Regards..

[sibe]

Try running the extracted audio file through AC3fix.

Sibe

[engel]

Well, folks, thanks a lot for that astoundingly rapid reply!!

I tried ac3fix - and it worked! Actually found some frameerrors.
Interestingly, the fixed file would cause wmp 6.4 to crash with an
error, whereas it would not do so with the unfixed file.

I ignored this and applied headache next to convert the fixed ac3 into wav - now it works!

I did not follow the besweet issue at this point.

Will post summary of steps/output generated satisfaying or not after
having finished with everything since I believe this to happen quite often (i.e. people posting huge files with ac3 audio in the donkey).
Although I appreciate posting movies, I feel it's a little overdone: After all you can only watch the movie on your computer, perhaps with a beamer attached, but do you really need Dolby surroung under these circumstances?

Thanks once more for the very essential and down-to-the-point information the doom9 site provides us with ...

Siggi Engelbrecht (Germany)

[MaTTeR]

Recompressing a Divx video is a very very bad idea:rolleyes: Your quality will look pretty nasty and needless to say you will most likely be wasting your time.

[engel]

I disagree! I just have finished with this biz, and it would seem the entire recompressed movie to be ok, both audio and video. Actually I do not see a large difference between the large DivX LM file and "new" DivX 5 file. Sound (just a quick check) was also ok.
Will check more thoroughly and summarize later on.

I should like to mention that I ran a full recompress double pass VD1.4.9/DivX 5.0 which took around 8 hours (750 MHx PIII).