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5.1 ac3 channel missing!!

Discussion in 'DivX / XviD' started by jay800, May 21, 2003.

  1. jay800

    jay800 Member

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    I have just finished creating a divx of the matrix and it looks great but when i play it the centre channel is missing from the audio.
    I encoded it using the divx 5.0.5 pro codec in virtualdub. I did 2 passes then used virtualdub mod to add the ac3 audio track that dvd2avi produced. When virtualdubmod adds the ac3 it says that it is 5 channel and not six - as the original on the dvd was. So somewhere in between the dvd and the dvd2avi file something has gone wrong - any ideas? I used dvd decrypter to rip the vobs. I have also tried using nandub to add the audio with the same result - perfect surround sound but no voices! - i have checked all my ac3 settings and they are fine!
     
  2. NoobCoder

    NoobCoder Member

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    I have the same problem. This really sucks cause i've spent alot of hours compressing and now the stupid audio file doesn't combine with video right. I tried the DTS and AC3 tracks and the DTS and Dolby Digital light on my 5.1 box doesn't come on. If i play the individual ac3 or .dts file from creative's playcenter, it works fine and goes into 5.1 mode. Sometiems i get no center audio like you and other times I get it but its not really 5.1 (voices through multiple channels). BTW I followed the DVD to xvid ac3 guide and am using dvd2avi and several versions of virtualdubMod.

    Did you ever find a fix?
     
  3. NoobCoder

    NoobCoder Member

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    ok well the best i can get is what sounds like real DTS from the front speakers. No action in the rear speakers and no decoder DTS light on my 5.1 receiver. Either VirtualDubMod doesn't take the real DTS file and combine it correctly with the avi , or soemthing is decoding the signal before my recevier?

    I thought my problem was in dvd2avi under DolbyD Decode. I had on that dynamic range control so i turnder it off and now i get what i mentioned above but not full surround. I uninstalled all of my ac3 filters/codecs

    Does anyone know if true DTS or DD 5.1 is broadcast undecoded after VirtualDubMod combining??
     
  4. jay800

    jay800 Member

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    I did fix the problem -it turns out that in the ac3 codec settings i had the 'sample format' set as 24bit PCM. For some reason it will only work if that is set to 16bit PCM - once i did this i have had no further problems-There was no actual encoding problem. As for using DTS i dont know - i find it is to large since i am encoding 2 cd divx's The difference in quality is not (in my opinion) noticable from ac3 and the ac3 file is half the size. I used nandub from www.doom9.com rather than virtualdub mod to multiplex the sound. I also used a combination of the guides on here - the 16:9 anamorphic for the video and the xvid ac3 guide for the audio. If the tracks are mixed up on the ac3 track you have probably got the 'dolby surround downmix' selected on dvd2avi - or you ripped the 2 channel ac3 off the dvd. Try using dvd decrypter to rip the vobs and enable stream processing so you only get the streams you want.

    Hope this helps

    J
     

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