I was wondering why some video files (i usually have avi, then convert into mpeg with TMPGEnc) will only come out stereo, but some i have had come out with pro logic sound. I have checked the format of these videos and they are exactly the same.

I want to be able to make my own VCD with pro logic, as i realise that it can't contain any form of digital sound (dolby digital, DTS)

-- Stuart Etcell (Runningman@football.com), January 13, 2002

Answers

VCD has only two audio channels that can used for a variety of purposes including straight stereo, Dolby Pro-logic, ch1 and ch2 for dual language movies, and voice and music channels for karaoke. Dolby Pro-logic is a method for matrixing 4 audio channels into the available two, and then using active steering in the decoder later to try to retrieve as much of the original four as possible from the two channels they were matrixed into all analogue processes. Making YOUR OWN Pro-logic soundtracks, if I get u correctly, has little to do with VCDs and its two available audio channels. VCDs, along with other 2-ch media (like VHS tapes, audio CDs, MD, etc.) merely accept what's thrown into it. To do your own Pro-Logic, you have to have a sound editor that can accomodate at least 4 tracks, edit, equalize, and preview the contents of those, then matrix them into 2-channels with the Dolby Pro-Logic standard. The resulting 2-ch is encoded into Layer-3 audio for VCD.

-- Mehmet Tekdemir (turk690@yahoo.com), January 14, 2002.

technically for vcd the audio is layer 2 not 3. and to make the answer to stuart easier to understand..you cant have pro logic on a vcd.just stereo.

-- john boy (johnbmx4christ@yahoo.com), January 14, 2002.