Vegas & AVCHD AC3

ECB wrote on 4/12/2009, 6:45 AM
When I load a Sony CX12 DD 5.1 .MTS file in Vegas two uncompressed audio streams are created using it own ac3filter. One stream is a downmix 2 channel ac3 and the other stream is 6 channel ac3. Vegas does not perform the 2 channel downmix correctly (right channel is loud - Sony needs to fix this). Once Vegas has been launched Cineform uses this Vegas codec Unfortunately, when you convert a CX12 DD 5.1 .MTS file with Cineform HD Link you get a Cineform file with the same badly downmixed 2 channel ac3 but not the 6 channel ac3. In order to get good 6 channel uncompressed audio I need to use a different/good ac3 filter like but I don't if Vegas' ac3filter and a new ac3filter will play well together. It would be great if Vegas offered the option to disable/not install their ac3filter and avoid any conflicts. Any help would be appreciated.

EB

Comments

blink3times wrote on 4/12/2009, 8:09 AM
Not at all sure what you're saying here.

I have done a screen shot of a AC3 file in Adobe Audition and the same sample in Sony Vegas. They look essentially the same to me (bare in mind that they're not at the same level of magnification... but as close as possible).

The only problem that exits with Vegas's import of MTS ac3 files is that you will note the LFE track is flat-lined (Sony has labeled this a bug and knows about it).

http://s616.photobucket.com/albums/tt245/Bob_sanders/?action=view&current=Vegas.jpg
http://s616.photobucket.com/albums/tt245/Bob_sanders/?action=view&current=Adobe.jpg

As for Cineform,

What I do is convert, import the AVI's, delete the audio, import the mts files, delete the video. You're left with cineform avi's and the original AC3 audio.
ECB wrote on 4/12/2009, 8:50 AM
I agree, the 6 channels look fine except the flatlined LFE. However, right click on the audio channel and select properties > media > and select audio stream 1 stereo downmix. The right stereo channel is louder than the left channel. Yes, I can do my own stereo downmix from the 6 channles but the stereo downmix should work properly.

The other problem is after Vegas has been launched Ciineform HD link looks for an uncompressed audio track and the only one it finds is the stereo downmix not the 6 channels stream. I would install another ac3filter which would solve the problem if I could disable the Vegas filter.

As you suggest, and I have been doing, is to transfer the video than add the 6 channel audio from the original. Unfortunately using split scenes is out.

Ed

PS Lauch Vegas pro and then close it. Open AE CS4 and import a 6 channel MTS file. The only audio will be the stereo downmix. :(
blink3times wrote on 4/12/2009, 9:21 AM
I have always assumed that this is more a cineform error than anything else. I have Neo.

When I first installed neo (with Vegas and dvda already installed) it said that I didn't have a AC3 decoder installed and directed me to a free one on the net. Downlaoded and installed... and neo STILL can't see it.

You can however experiment with removing DVDa and see what that does for you. The AC3 licensing i believe is housed in dvda so if you uninstall dvda that should effectively disable Vegas's ac3 codec. (I should point out that I have not tried this)

You're right BTW... the right side on the downmix does seem to be higher in gain
blink3times wrote on 4/12/2009, 9:26 AM
"PS Lauch Vegas pro and then close it. Open AE CS4 and import a 6 channel MTS file. The only audio will be the stereo downmix. :("

I don't think CS4 has AC3 import capability.... does it? I believe you have to purchase a separate decoder.

You can try this:

http://ac3filter.net/
ECB wrote on 4/12/2009, 2:37 PM
I imported a 5.1 MTS file in Premiere Pro CS4 edited and rendered to DVD with a 5.1 downmix to stereo. I don't had the Surcode encoder installed. Everything worked fine. I am not sure AE CS4 support 5.1 but everthing is getting a little foggy. :)

"I have always assumed that this is more a cineform error than anything else. I have Neo."

I agree.

Ed
blink3times wrote on 4/13/2009, 3:11 PM
ECB:

You emailed me for the AC3 plugin for Adobe Audition;

http://ac3filter.net/projects/audition