Any way to compress audio tracks?

[rhobite]

I'm using InstantCopy 8 to compress the Tenacious D DVD set. The problem is, the audio on the disc is uncompressed PCM (1.5 mbps!). Almost half the DVD is taken up by the audio, which IC8 doesn't seem to compress. The disc ends up looking awful because the audio takes up so much space. Is there any way to compress the audio to MPEG layer 2 or AC3, either through IC8 or another tool? Thanks.

[mrbass]

Besweet I'm sure can. Does TMPGEnc DVD-Author accept .mp2. I have no clue. Only time recently I've used .mp2 audio is create a dvd slideshow with memeriesontv and the option was either PCM or .mp2 and size wise the PCM was a joke like you say.

Maybe in the audio forum they might be able to better help you.

[FredThompson]

You haven't tried DVDShrink?

[m1482]

- DVD Shrink doesn't compress audio!!!

- You can convert PCM audio to AC3 audio using BeSweet :)

[rhobite]

I guess I would have to remux it with ifoedit or something. Probably not worth it. Too bad there isn't a one click tool that does audio. Thanks for the replies.

[KpeX]

Originally posted by rhobite
I guess I would have to remux it with ifoedit or something. Yes, that would be the solution. Originally posted by rhobite
Too bad there isn't a one click tool that does audio. It would be simple if someone wanted to implement it, there are open source AC3 decoders and MP2 encoders available. The main reason it doesn't exist is that few DVDs have PCM audio and the size decrease with normal audio is quite minimal compared to compressing video.

[robot1]

If one click tool try to save a few MB with still pictures for extras, why not compressing audio?
If I keep two languages, I would keep one in ac3 (5.1) and another in mp2 stereo.

[Kedirekin]

It's because the audio is already compressed pretty small, and there just isn't much to be gained by compressing it further.

For example, a 2 channel AC3 track on a 15 minute extra is only about 20 MB. Even if you could shave it to half the size, that's only saving 10 MB. The video for the same 15 minute extra is probably on the order of 500 MB, and converting it to still frames saves you between 400 and 450 MB.

Adding the ability to compress the audio just isn't worth the effort, especially considering how badly the audio quality would be degraded for even minimally significant savings in bitrate.

[jippiejajee]

Although it is an interesting discussion I think the original question remains unanswered, the man asked if there is a simple way to compress uncompressed PCM audio during copying process. He is right that uncompressed PCM audio consumes a lot of space and at least it can be compressed with a factor 5 (usuing for instance mpg1 audio spec)without any significant noticeable (for normal human being's) loss in quality. Compressing the uncompressed PCM audio will give him for sure a lot of extra space for video and as such quality of the video. For the rest I agree the when it is compressed to for instance mpg1 it makes little sense to compress it further. However the first step compressing uncompressed PCM makes senses.

So how can this be done: compressing PCM audio during the copying process, or another option could be: how to do this before starting the IC (or similar)process.

[rhobite]

Originally posted by jippiejajee
So how can this be done: compressing PCM audio during the copying process, or another option could be: how to do this before starting the IC (or similar)process. That is an interesting idea, you could just pull the audio stream out of the vobs, compress it and remux it, then start the IC process. I'm not very good with ifoedit and the other low-level tools, would this be easy to do? A couple problems I see is the vobs would be less than 1GB, and PCM audio streams are numbered starting at 0xA0 rather than 0x80.

[echooff]

Does TMPGEnc DVD-Author accept .mp2. I have no clue. Yes it does. However, it doesn't like lpcm audio.

[rpboy]

Originally posted by rhobite
That is an interesting idea, you could just pull the audio stream out of the vobs, compress it and remux it, then start the IC process. I'm not very good with ifoedit and the other low-level tools, would this be easy to do? A couple problems I see is the vobs would be less than 1GB, and PCM audio streams are numbered starting at 0xA0 rather than 0x80.

Yeah, I've been wondering the same thing myself. I posted the question over in the IfoEdit forum to see if those people there who really know their stuff when it comes to this sort of thing had any guidance.

http://forum.doom9.org/showthread.php?s=&threadid=68795

[Mug Funky]

actually, LPCM is very common these days. the only reason it's not been implemented into one-click backup programs i think is because the bulk of DVD backups are for movies.

on music/live DVDs the format of choice is LPCM... i've got buckets of the things.

recompressing AC-3 should be disabled - it won't handle anything below 192kbps well (2ch), and mp2 handles it worse.

but compressing 2ch LPCM to 224kbps ac-3 should be transparent for most things. more than enough for a backup.

[valnar]

So can anyone tell us how to do this easily with Ifoedit or another tool?

Danke.

Robert

[DnGermany]

No one click solution for that! You would have to reauthor the dvd.

[valnar]

Which application is best for reauthoring while maintaining the original menus, chapter points, vob's, etc?

-Robert