LPCM sound in MPEG2

[alchemy1]

Hello,

If I output my video using Vegas in PAL DV format with LPCM sound as an avi file, how do I retain the LPCM sound when I go to convert the avi to mpeg2? Is the video encoded differently from the audio?

Also, if I want to add 6 mono channels after creating a 5.1 track, does that get added in at the authoring stage, or does that have to be encoded into the avi, and then the mpeg2 ?

Programs:

- Song Vegas Video Editor
- TMPGEnc DVD Author 1.6

Thanks in advance for any help.

[guns1inger]

From Vegas you can output either a programme stream (combined pmeg2 video and audio of your choice, including LPCM), or you can output the video in one render, and an uncompressed wav file (which is what LPCM is) in a seperate render. You can then use this audio when authoring. Remember that LPCM does take up a lot of space.

I'm not sure what you are trying to do with the 6 mono files. You can certainly output each one sperately from Vegas, and use them when authoring, but you will get 6 mono audio tracks. Or do you intend to then encode them into a 5.1 AC3 or DTS audio track ?

[alchemy1]

Thanks for your response.

From Vegas you can output either a programme stream (combined pmeg2 video and audio of your choice, including LPCM)

OK, this is exactly what I want to do. The problem is that when I click "Render As", and set "Save as Type" to MPEG2, the audio always changes into something compressed. I tried to change it in the "Custom" option, but it only offers bitrates and such, no LPCM option.

I'm not sure what you are trying to do with the 6 mono files. You can certainly output each one sperately from Vegas, and use them when authoring, but you will get 6 mono audio tracks. Or do you intend to then encode them into a 5.1 AC3 or DTS audio track ?

Exactly, I intend to encode them into a 5.1 AC3 track. So after I get my 6 mono channels I should encode them into an ac3 file, and then import that ac3 file when I go to author, correct?

Again, thanks.

[guns1inger]

There is a Dolby certified, high quality AC3 plugin for Vegas (part of the DVD pack with Architect, or available standalone) that lets you output 5.1 from the timeline. Worth the money, IMO.

I seem to recall now a recent post regarding programme streams and audio formats. I believe you cannot have a programme stream with LPCM audio. You will have to output as elementary streams then author them back together.

[alchemy1]

There is a Dolby certified, high quality AC3 plugin for Vegas (part of the DVD pack with Architect, or available standalone) that lets you output 5.1 from the timeline. Worth the money, IMO.

Again, thanks, I decided against the 5.1 option. No need really because from what I read, hacking a 2.0 track into 5.1 doesn't do much. It really needs to be recorded that way.

I seem to recall now a recent post regarding programme streams and audio formats. I believe you cannot have a programme stream with LPCM audio. You will have to output as elementary streams then author them back together.

But, after all that, I got my LPCM. I just output the video fom Vegas in PAL DV format with LPCM, and then re-encoded it with TMPGEnc to mpeg2 with LPCM. A longer process, but it gets the job done. I'm a little confused as to why Vegas wouldn't offer an LPCM format with it's mpeg2, considering it's such a simple audio format and there wouldn't be any need for another codec.

[guns1inger]

I would g-spot you tmpgenc output to confirm LPCM

[alchemy1]

I would g-spot you tmpgenc output to confirm LPCM

Well I actually redid the entire project from scratch, but when I encoded the avi with TMPGEnc, it output a m2v(I think) file and a wav file, so I figured that had to be right. I'll check, but I think TMPG did its job.

Also, would you happen to know if in Vegas, the audio and video have to be the same size to group the files together? I have an audio and a video file, and I was trying to "lock" their position on the timeline and couldn't seem to do it. Thanks.