Dolby Digital 5.1 extraction

[netlizard]

Hey,

I have gotten programs that were recorded in normal audio to convert fairly well. Ran into some problems recently with a new program that I am trying to extract and encode and I think that it is because it is a program that is recorded in Dolby Digital.

I am using TyTool 7r4 to extract and do the spliting into the m2a and m2v files. Then using DVD2AVI to create the d2v file and lame to create a wav file. Then using VirtualDub to find the commercials and edit frames. And finally TMPGEnc Plus to do the final encoding... I got the information from this URL:

salfter.dyndns.org/tivo2svcd.shtml (http://salfter.dyndns.org/tivo2svcd.shtml)

When I get the final product and in VirtualDub, I get pops and clicks in the audio and the audio seems to be trailing the video more and more as the clip progresses. What do I need to do different to process the audio for these programs?

Thanks,
Netlizard

[Pro-289]

Those instructions were written a long time ago.

Always use the latest version of TyTool (http://www.dealdatabase.com/forum/showthread.php?s=&threadid=25588#post105979). I think there's been a DD fix in this version. With older versions, sometimes when you had a PTS reset in the stream, it would mess things up.

I haven't tried my problem DD .TYs yet with this latest version. But if you have holes in your audio stream (may not be apparent), and TyTool doesn't yet patch DD holes, then you'll get audio sync problems.

Follow my post here (http://www.dealdatabase.com/forum/showthread.php?s=&threadid=8092&perpage=15&pagenumber=4#post108228) if you're going to create an SVCD.

The problem is once you split the .TY into 2 files, there's no more sync. If the audio gets processed and is missing some information, then when you join them back together, you'll get audio sync issues. But if you have a good .TY file, then you should be able to DeMux/split the .TY into .MPA & .M2V, then use BeSweet to convert your DD audio into MP2 audio, then Mux/join them back together using TMPGEnc.

[captain_video]

A lot of programs containing Dolby Digital soundtracks may be recorded with segments at the beginning of the clip that have the normal mpeg layer 2 audio soundtracks. When it switches over the the DD portion things can get screwy. Actually, it's the mpeg II audio that hoses up the process since TyTool is probably looking for the DD soundtrack.

Whenever I extract a PPV movie with a DD soundtrack I usually set a jump point in TyTool to skip past the opening mpeg II segment and begin the extraction or splitting process at the beginning of the DD segment. Usually a setting of about 60-100 chunks for the initial jump is sufficient for a normal PPV movie (the opening segment is approx 30 seconds before the actual movie begins). Broadcast shows will vary due to other variables (commercials, trailers, etc.) so set the initial jump point to compensate for the differences.

You can use jdiner's audiocheck program (see attached file) to see where the DD portion actually begins. You can also use tydemux for splitting the files. Tydemux will scan through the entire segment to see what type of ausio is used for the majority of the clip and jump right to the point where the DD soundtrack begins and start splitting from that point.

[netlizard]

I downloaded and tried TyTool7r7. The Latest as of 7/2/2003.

Got the ty file for the Scrubs episode from tonight and converted it per your procedure.... Now the audio lags the video when I play it after converting it to the mpg file. I didn't make any cuts because I wanted to just see how it would do. Is this normal? I didn't go all the way to SVCD because I didn't want to make another drink coaster. ;-)

When I tried the procedure on a DD5.1 Track, Sex and the City from Sunday night, I got an error saying that I couldn't transcode Dolby Files... ?!?!?! Is this because of the version 7r7?

Thanks,
Netlizard

[netlizard]

What do you do with the DiffTime? Is this the problem?


Detected Tivo Type: DTivo
Detected Audio Stream Type: MPEG Layer II
Final standardAudioSize = 492
Final standardFrameLength = 480
Final standardAudioDiff = 2160 or 00:00:00.024
First Video PTS: 00:02:09.266
......... 100......... 200.......
11111 -> Chunk contains neither audio nor video data. Stop here...

DiffTime = 43.423002 (43423) == 0.723717 Minutes

total = 35520512

[Pro-289]

Originally posted by netlizard
I downloaded and tried TyTool7r7. The Latest as of 7/2/2003.

TyTool is at version 7r7a now. But it does not support DD audio transcoding at the moment. You'll still need another program if you want to convert DD audio to MP2, like BeSweet. You can get it at doom9.org. If you have any sort of audio holes or CRC errors in your DD audio, then you'll get sync errors after you transcode your DD audio to 44.1kHz.