Combining AC3 Audio and MPEG2 Video

Discussion in 'Computers' started by MarkHastings, Jan 19, 2005.

  1. MarkHastings

    MarkHastings Executive Producer

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    First off, how do you capture AC3 audio? What appls do this?

    The system I have will capture PCM audio and I use Adobe Encore to re-encode to Dolby digital audio, but I need an app that will create an MPEG2 files with AC3 audio. Is this even possible???
     
  2. Rob Gardiner

    Rob Gardiner Cinematographer

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    TMPGEnc has the capability to "mux" or "multiplex" an MPEG-2 video stream and an AC-3 audio stream. You need to register, as the freeware version of the program will NOT do this. I would be surprised if other DVD authoring tools didn't also have this capability.

    If you're looking for some other means to create your AC3 file, I'm pretty sure BeSweet (open source program) can do the job.
     
  3. MarkHastings

    MarkHastings Executive Producer

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    Thanks Rob. I've heard of TMPGEnc for a long time now, but I had opted for stand alone MainConcept's MPEG Encoder. It unfortunately doesn't do AC3...

    I have a machine that captures MPEG2's in real time, but that also uses MainConcepts encoder, so I can't capture AC3 either.

    Again, if I do need AC3, I usually capture a DV clip and then use Adobe Encore to create the AC3 audio...I was wondering if I could go this way (for now) and then use those files with TMPGEnc? Encore exports a ".m2v" (which is obviously the MPEG video), a ".ac3" (which is obviously the DD audio), but it also exports a "..m2v.mcses" - I assume that has to do with the MPEG video?

    I assume I could take the M2V and the AC3 file (that Encore generates) and use TMPGEnc to mux them together?

    I posted the files if anyone has the full version of TMPGEnc, to see if these files work.

    Thanks

    Here is a zip file of the 3 exported files:
    ZIP file


    or individually:
    -AC3 file
    -M2V file
    and if needed
    -MCSES file
     
  4. Jeff Jacobson

    Jeff Jacobson Cinematographer

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    Yes, you should be able to do that.
     
  5. Steve Felix

    Steve Felix Supporting Actor

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    I have the full version of TMPGEnc, and it worked. Here's what it gave me (your ac3 file played the same way by itself as it does with the video...).

    Besweet, free software, does a lot with AC3. (Which is on the edge of legality, I believe, since Dolby requires a license for the technology.) It doesn't deal with MPEGs as far as I know, though.

    The *.mcses file is a MainConcept session file and is unnecessary to the process.
     
  6. MarkHastings

    MarkHastings Executive Producer

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    Steve, thanks for muxing them for me. [​IMG]Oh :b I didn't realize that my original AC3 stuttered like that.

    Well, now that I can use this utility to mux the audio and video, any one have ideas about creating AC3 files? I guess I can use Encore to do it for now, but there's got to be a better way.

    I guess I should tell a little back story. I have a Digital Rapids system at work:
    http://www.digital-rapids.com/Products_Servers.html
    I use this to capture (in real time) any type of compressed file. For DVD, it uses Main Concepts encoder, but (as explained before) the only audio options are PCM or MPEG-layer2. In order to do Dolby Digital audio, I have to capture a DV file and use Encore to re-encode.

    Our company is looking to provide content for Video on Demand services, but they are requesting MPEG2 clips with Dolby Digital audio (combined). It would be much easier (and less time consuming) if I could capture these on the fly and not have to recompress with Encore.

    Anyone know of a real-time AC3 audio encoder? I can install the encoder and use it on the Digital Rapids. This way, I could capture the video (with PCM audio), then just recapture the audio as AC3 (separately) and mux them later. This isn't perfect, but it would save me time as I would avoid Encore to re-encode.

    My other question is about the TMPGEnc. If I have an MPEG2 file with PCM audio, can I mux that with the AC3 file? Meaning, will TMPGEnc ignore the already combined audio and replace it with the new AC3 audio? I know I can do this with Main Concepts stand alone app.
     
  7. Jeff Jacobson

    Jeff Jacobson Cinematographer

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    If you're capturing video with PCM audio, you can just use BeSweet to convert the PCM audio to AC3, instead of recapturing the audio separately in AC3 format.
     
  8. MarkHastings

    MarkHastings Executive Producer

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    I was researching the forums at http://www.videohelp.com/ and a lot of people were complaining that BeSweet has synch issues.
     
  9. Steve Felix

    Steve Felix Supporting Actor

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    I can say that if you have an MPEG2 muxed with an MP2, TMPGEnc will work as you describe (replacing it with the ac3). Haven't tried it with PCM, but I assume it would work.

    I don't know of a popular realtime AC3 encoder. I use Encore, also. This is probably the type of thing you're looking for, but the quality is probably low and it seems to be a Linux only thing: http://essej.net/ac3jack/

    If you need to do any MPEG2 merging and cutting, I've had more success with MPEG2VCR (http://www.womble.com/vcr-text.htm) than with TMPGEnc.
     
  10. Jeff Jacobson

    Jeff Jacobson Cinematographer

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    That's a good thing to be aware of (which I wasn't).
     

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