Extract Ac3 (5.1) From Avi

Discussion in 'MPEG-1 and MPEG-2 encoding (AVI to DVD)' started by o.u, Aug 30, 2005.

  1. o.u

    o.u Member

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    I have avi video on my computer, and i want to extract the audio from it, and i want the audio to be AC3 with 6 channels (5.1).
    can someone tell me how i can extract AC3 Audio file from Avi that will be with 6 channels (Dolby Digital with 5.1 channels)?
    thanks to the helpers.
     
  2. aldaco12

    aldaco12 Active member

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    Has the AVI AC3 sound or, as often it happens, simply MP3?
    Open the AVI with VirtualDubMod (you'll see which kind of 'audio stream' it has).
    If the AVI already has AC3 sound, simply do Stream___Stream List___Demux. Nothing easier.
    If the stream is not AC3 but, for instance, MP3, you can extract it, as explained before, byt it must encoded MP3 --> AC3. Your PC must be equipped with AC3 codecs and a suitable application (HeadAC3he, for example, but you need the codecs anyway).
     
    Last edited: Aug 30, 2005
  3. o.u

    o.u Member

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    and what do i do if the real audio of the movie is mp3, and i want it to become AC3 (5.1)?
    thanks again.
     
  4. aldaco12

    aldaco12 Active member

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  5. o.u

    o.u Member

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    Now tell me, if i cant hear AC3 (5.1) on my computer, it means i wont be able to hear it on my DVD-Player?
     
  6. pfgd270

    pfgd270 Member

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    Sorry to jump in, but along the same lines - Is it possible to convert from WAV to AC3 in a similar manner, or can you not do so with WAV format?
     
  7. aldaco12

    aldaco12 Active member

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    To o.u.: if you don't have Dolby Surround speakers, you'll hear a DVD with AC3 as if you heard a VCD with MP2 sound or, if you watch AVI, an AVI with MP3 sound (that is, as you hear music).

    To pfgd270: as I tried to reply, maybe in Doom9's Forum guide ( http://forum.doom9.org/showthread.php?t=83752 ) there is written how to do so. Or, in http://www.afterdawn.com/guides/archive/convert_avi_to_dvd.cfm , we have a guide to make AVI -> DVD . In that guide, you'll see that if you start from an AVI with MP3 sound (the most common ones) you'll create , with TMPGenc, 2 elementary streams: a M2V video file and the audio file (if you dont have AC3, you'll use MP2, which is like the one you use on (S)VCDs, apart that it is resampled 48 kHz (compliant with DVD specifications) instead of 44.1 kHz [compliant with (S)VCD specifications).
    The 'lesson' this teaches is: garbage in = garbage out. If you start with a MP3 sound (100 MB for an average movie) , which quality can an AC3 made from it (200 MB for an average movie) have? Poor, and therefore making an AC3 is useless.
     
  8. pfgd270

    pfgd270 Member

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    thanks for the explanation aldaco12... good to know someone knows their stuff...
     
  9. Minion

    Minion Senior member

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    You can Do this With "Virtual-Dub" and "BeSliced"....

    What you do is Run V-Dub and Load in your AVI file and then go to "Audio" and set it to "Direct Stream Copy" ,Now go to "File" to "Save as Wav" and give the File a Name and Save it....

    After it has saved the File rename the ".wav" extention to ".ac3" ,Then Run "BeSliced" and Drag and Drop the Renamed ac3 file on to the BeSliced Window and then select "Fix File" and then it will rewrite the AC3 file as a True AC3 file that you can use to author your DVD...

    What V-Dub does is extract the AC3 audio but it has a wav header and extention so after renameing the wav to AC3 you use BeSliced to Fix the Header so it is a AC3 header so in the end you have your Real Working Dolby AC3 audio file.....

    Cheers
     
  10. aldaco12

    aldaco12 Active member

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    You can fix the 'AC3 with WAV header' using VirtualDubMod. If you open the movie and press Stream___Stream list you'll see AC3 in the list, it it's AC3.
    Clicx on 'Demux' and VirtualDubMod will extract a 'true' AC3 audio file, with no need to fixing it...

    Most of the AVI have MP3 CBR, some (erroneously) have MP3 VBR and need to be fixed, some have AC3 sound.
     

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