Prologic on svcd

[thompa]

Hi!
I know that there are many posts regarding different audioformats, but i'm still curious. If I have a divx and convert it to mpeg2/svcd will there be anyway for me to see if the sound is Dolby Prologic? Could you , for example, in Tmpgenc convert the sound to Prologic?

[bugster]

Do you really mean Dolby prologic as opposed to Dolby Digital 5.1 (which is what most commercial DVD's use). Prologic is the old analog surround sound format. The surround info is somehow encoded into the two normal stereo channels, so any stereo stream can carry this info. DD5.1 also generally carries the same info so prologic can be decoded where DD 5.1 encoding is not available.

Basically this means that if the source audio contained prologic encoding, then the final encoded audio will carry it too. But be warned, some lossy compression methods will lose some of this info and so reduce the surround sound experience.

The only way I know of to see if pro logic is present is to play the audio through a decoder and see if the 'prologic' light lights up or sound comes out the rear speakers.

[thompa]

Thanks for the reply!
Basically, what i'm looking for its the best possible sound on a SVCD and if I have understand i correctly so can you not have AC3 sound on a SVCD. If you are using TMPEnc to convert divx to MPEG and virtualDub to extract the sound, do you automatically get the best sound possible?

[bugster]

If your Divx has AC3 (DD5.1) or stereo soundtrack, ripped from DVD then it is likeley to contain Dolby Pro-logic encoded surround sound. If it sia VHS or some other form of capture, there is a pretty good chance it is simply stereo.
In terms of getting the best quality audio for SVCD, use toolame within TmpGenc, installed as an external audio encoder to get an improvement over the default TmpGenc audio. Also, if your source divx file has 48khz audio, use vdub to do the conversion to 44.1khz audio (required by the SVCD standard) when seperating it from the video.

Hope this helps

[vcd4me]

I would just like to point out that I once got into a heated debate over this on this site. I was on the loosing end and this is what I learned.

Any 2 channel stereo sound can be encoded into pro-logic as long as you receiver has pro-logic (most do) !

That is why vhs and cable tv have surround sound (pro-logic).

A pro-logic receiver just taking a stereo sound and encoding it to surround sound. However the rear channel is mono, meaning the sound is the same coming out of both rear speakers.Example if a plane is flying on the right side of the screen front to back you will actually hear the sound also on the rear left.

Bugster wrote

If your Divx has AC3 (DD5.1) or stereo soundtrack, ripped from DVD then it is likeley to contain Dolby Pro-logic encoded surround sound. If it sia VHS or some other form of capture, there is a pretty good chance it is simply stereo

.
If you are going to play your divx on computer and have a good sound card you will have ac3 sound and if you have a good tv out card then you can play a movie with ac3 on your tv and surround sound receiver.However any movie will play in prologic as long as it is stereo even a captured vhs.

For further reading visit www.dolby.com

Hope this helps
VCD4ME