ac3 -> wav (for cutting) -> ac3

[st321]

I plan on cutting a movie from my DvD to include all the special scenes from the second disk and also cut around in some scenes I believe I could change a bit ... problem is, I want the resulting product to also have 5.1 sound that I can play ...

Last time I tried this (some years ago ;)) I didn't complete the task because compilers were bugging me (giving me bad frames every now and then) and the audio part was a bit complex ... the fun of it just left me :(

Now I want to try it again ... do you have some tips for me how to do it better than last time?

I did this ...
- created a pseodo .avi with VFAPI so I could cut around in MediaStudios without converting the video stream
- extracted the 6 soundchannels from ac3 to 3 dual mono .wav files (using the Azid1 part of BeSweet GUI) so I could cross fade the volume on cutscenes (and enhance surround sound, since the special scenes seamed to have a different sound level)
- compiled the video in Media Studios - which gave a pretty bad result ... so I tried a mpeg2 output - a pseodo avi of that and then ... erm ... ah ... I think I followed a Guide from here off of that ... can't really remember anymore ;)
- tried to put the edited .wav files back together to an ac3 file.

No, finaly, to my questions ...

- what settings do I nead to get the exact copies of the sound channels from the ac3 files to my the .wav files ... LFE 2 LR -90db? leave it unchecked? 0db?, LFE 2 LFE, Center Downmix and so on. I'm totaly clueless at the moment (tried to find it in some guides but I seam to be to dumb to understand some of them ;))

- how do I get the wav files back together again to an ac3 file? Does it work with 3 dual monos or do I have to work with 6 monos?

- how should I try to convert the video stream? Is there maybe a much better cuting program (that also alows me to do those Star Wars slide-fades, subtitles, volume editing ...) maybe one that works with ac3?

- would you propose me a totaly different approach?

Thank you for reading, hope somebody can give me some info or links to good guides on simular subjects.

[st321]

Hehe, ok, I realise I asked a lot of non-audio related questions ... to priorities it, audio question only ...

What program with what settings do I have to use to get exact replicas of the ac3 streams in .wav files?

Can I put the audio into 3 stereo .wav files and reconnect them with Sonic Foundry Soft Encode (manualy putting them in)?

Just now I tried a few settings with azid ...

azid.exe -oc,lfe --chc=none,0db --chlfe=none,0db --ch0=none,0db --ch1=none,0db -m stereo -d 3/2 -c heavy -L 0 -l 1 -C -3db -S -3db -F wav "e:\EpI\CutScene1\Scene1-vstrip.ac3" "e:\EpI\CutScene1\Scene1-Ce-Sub1.wav"

... resulting in what looks like exact replicas of the ac3 stream when I compare them in Sonic Foundry Soft Encode exept that the .wav files seam to be louder. Is this ok? Should I just test id I get the same ac3 when I reencode? Does anybody have settings for LFE 2 LR (I used 0), LFE 2 LFE (I used 1) , Center Downmix (I tried -3db), Surround Downmix (I tried -3db)
Thanks

[DSPguru]

http://BeSplit.doom9.org

[st321]

I'm sorry to say that this link did not help me, BeSplit seams to be able to make 6 mono wave files only from a Multichannel wave file. And although I seam to be able to cut ac3 streams I can't fade over some tracks or edit the sound in other ways (at least not that I see :().

I am experimenting around with the azid settings using the BeSweet GUI ... but to be honest, I don't quite make out what settings result in what outcomes and if those outcomes get me the correct ac3 afterwards because in encoding a new ac3 apparently some channels are downmixed and filtered again making it difficult to "see" what results in simular results.

I guess stupid me needs to see an exact code line or settings to demux the 6 audio channels correcty ... from an ac3 to 6 mono waves (or better 3 stereo waves with 2 channels each) ... so I can remux them after editing each channel.

Still hope somebody can help this poor lost soul ;)

[KpeX]

As you mentioned BeSplit can demux a multichannel wave into mono wav files, just use BeSweet first to decode to a multichannel wave:

besweet -core ( -input "infile.ac3" -output "outfile.wav" -6chwav )

Then use BeSplit to demux into 6 mono wavs, and edit away :). hth,

[st321]

Man do I look like a fool now ... especialy since I noticed right after my post that BeSweet also seams to have the option to output 6 mono waves

BeSweet.exe" -core( -input "input.ac3" -output "output-" -6ch ) or does that give back a different and faulty result?

Thanks for the help

[KpeX]

Sure that'll work ;) if you get your six wav's.