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Possible to re-encode AC3 file to 5.1 Channels?

Discussion in 'DVD±R for advanced users' started by tdfuller, Apr 2, 2004.

  1. tdfuller

    tdfuller Member

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    Hi,

    I have no trouble creating DVDs, including converting some of my PAL DVDs to NTSC. I encode using AC3 video. Is it possible to re-encode the video back to AC3 5.1 surround?? I only can get 2 channel stereo.

    Here is what I do:
    1) Use DVD Decryptor to rip off all the files

    2) Use DVD Shrink to capture only the main feature, trim the credits off the end, and capture only the 5.1 channel AC3 English soundtrack.

    3) Use DVD2AVI to convert video to AVI and to convert the AC3 audio to WAV format, the necessary format for TMPGENC.

    4) I then use TMPGENC to convert the video and audio to NTSC, with 2 elementary streams: MP2 audio and M2V video.

    5) I use ffmpeggui to convert the new MP2 audio back to AC3. But it is only in 2 channel stereo.

    6) Use DVD-Builder to reencode and remux the video and audio to a useable DVD format.

    Please give me any suggestions.
     
  2. drchips

    drchips Active member

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  3. tdfuller

    tdfuller Member

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    Yeah, I already did. I greatly appreciate the reply. The fine print says DVD Author with the AC3 plugin still will not re-encode AC3 with 5.1 channels.

    "-Re-encode AC-3 sound
    You can also re-encode AC-3 audio, and even if there are bilingual broadcasting (used in some coutries).
    *But AC-3 with 5.1 channels or other multi-channels source cannot be re-encoded. "

    :(
     
  4. oddyseus

    oddyseus Guest

    I dont think that u have to fidlle at all with the audio.

    As long as the video in PAL has the same duration as the resulting in NTSC there should be no need to change anything in the ac3 file. They should be in sync.

    Besweet, however can change a pal ac3 to ntsc ac3.
     
  5. tdfuller

    tdfuller Member

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    Oddyseus,

    Thanks for the reply. I hope I was clear on my question, seems you may have misunderstood it. I have no trouble converting audio or video to NTSC. Its just that in the demuxing and conversion process, the audio is stripped down from 5.1 channels to only stereo (2 channel) audio. So far, I can not find a way to retain full surround (5.1 channel) audio while doing the NTSC conversion.
     
  6. oddyseus

    oddyseus Guest

    U might have misunderstood my post. I meant that u might be able to use the original ac3 file and not loose the 5.1 channels by using it as is.
     
  7. tdfuller

    tdfuller Member

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    :)

    OK. Yes I understand now... But if I dont run the original AC3(before the conversion) wont the audio be out of sync with the video because NTSC and PAL are slightly different lengths?
     
  8. tdfuller

    tdfuller Member

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    let me clarify... I meant if I dont run the original 5.1 AC3 through TMPGEnc as well as the video for the NTSC conversion then I think the video will be out of sync with the audio.
     
  9. oddyseus

    oddyseus Guest

    Pal films are accelarated to 25fps from the original film format of 24fps.

    NTSC films are 23.976 with pulldown flags to 29.97fps.

    Nomatter what u shouldn't face any problems if the final version of the video has the same duration as the original.

    If it gets to complicated to achieve u can always use besweet and check the pal to ntsc box for automatic conversion.

    But I think that u can try the original stream first.
     
  10. tdfuller

    tdfuller Member

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    I am going to try it. I will mux the original AC3 with the converted video stream and report back to you. Seems like it should work because NTSC/PAL has only to do with the frame rates per second. Thanks for your persistent help!

    Oh, by the way, do you have any idea on how to retain the subtitles, for the video, once I do a PAL to NTSC conversion? Somewhere along the way, either DVD2AVI or TMPGENC, or DVD Builder strips out the subtitles.
     
  11. oddyseus

    oddyseus Guest

    dvd2avi strips out the subs. It isn't designed to do subs at all.

    U may rip the subs with subrip, convert the frame rate to ntsc and save them for the authoring stage.
     
  12. tdfuller

    tdfuller Member

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    Oddyseus, I think you have been the most helpful person, at least in a long time! I used the original AC3 file and muxed it with the new NTSC video and the result seems to work great!

    Now all I have left to conquer is the subtitles. I did some checking, and my DVD authoring program, DVD Lab, does not do subtitles. I have to get DVD Lab Pro, which costs another $100. So I think I will pass on the PRO version.

    I notice that IfoEdit has a thing for subtitles under the author DVD menu at the top. It uses *.SUP format for subtitles. But, I would have to figure out how to set up chapters under IfoEdit, using CellTimes(*.txt) files which I dont know how to do? Other than this new thing, I think I can handle the audio, video, and subtitle portions of IfoEdit.

    Do you know how to use CellTimes to set up chapters in IfoEdit?

    Thank you again for all of your help!
     
  13. mastaprk

    mastaprk Regular member

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    I was actually curious what the best way to convert a PAL DVD to a NTSC format DVD is. I have tried to use Ulead to make it in NTSC format, but the DVD's quality is horrible and it gets choppy when there are fast movements. Any help would be appreciated.
     
  14. tdfuller

    tdfuller Member

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    Mastaprk,

    I will be happy to help. I started my search back in January for how to convert PAL DVDs to NTSC. I think I finally have found a way that I like and that has worked without fail. In addition, I notice no difference in quality between the NTSC and the original PAL. The only quality difference that I may notice is for shrinking the DVD to fit on to one DVD.

    Here goes:

    1) First, I use DVD Decrypter to rip the PAL DVD. You dont need to use it if you use Shrink, but I like to because it minimizes drive access.

    2) I use DVD Shrink to compress to one DVD. I personally like to remove all audio tracks except for the one english 5.1 channel track. I remove all subtitles because during the conversion process, you will lose the subtitles, which is not that big of a deal. I almost never play the subtitles unless I want to learn a foreign language. I also trim the beginning and end of the main feature. I trim all of the credits, and the intro stuff so as to have only the main film and this improves quality. A compression level of 70% or greater is good. The higher the better.

    3) I use DVD2AVI. I load the VOB files from the Video folder that Shrink created. I demux the audio file to AC3 format. The video is saved seperately.

    4) The most important step. I use TEMPEnc to convert the video file to NTSC format. It is relatively easy to use. You dont need to worry about the AC3 file. Save it for later.

    5) TEMPEnc takes a long time, about 4-6 hours to convert. Once finished, you will have a *.m2v video file and the original AC3 audio file. Now, use a good authoring program to remux the 2 files. I use DVD Builder.

    6) I use ImgTool to create a disc image from the newly created VOB files made by DVD Builder.

    7) I burn the image to a DVD disc using Roxio Easy Creator 6.

    It looks like alot, but it really is not bad. In January, it took me a little while of fiddling around and having patience, but now my system works well. I usually allow the TMPGEnc step to run overnight because it takes the longest.
     
  15. mastaprk

    mastaprk Regular member

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    Thanks for the info, I'll give a shot.
     
  16. tdfuller

    tdfuller Member

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    OK. Well if you have further questions later please ask.
     
  17. oddyseus

    oddyseus Guest

    Thank you for your nice comments and excuse me that took me so long to get back to you.

    Bad news is that ifoedit's ntsc authoring is a bit buggy and haven't been fixed yet. However it may work for you.

    These r some excellent guides that u might want to take a look at concerning ifoedit and authoring
    http://www.doom9.org/mpg/ifoedit-dvdauthor.htm

    in fact every guide in this section is a must to have.
     
  18. tdfuller

    tdfuller Member

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    Oddyseus,

    Once again, you are the man. I will check out the guide. I am over the hump now with PAL conversion to NTSC, now that I have full 5.1 audio. Subtitles arent that big of deal, rarely are they used anyway. I may try IfoEdit, but I dont want anything that hints at unreliable. I may step up later and just get DVD Lab Pro and that way I can have up to 8 subtitles.
     
  19. MysticE

    MysticE Active member

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    @tdfuller

    What would happen if after the first run thru Shrink you just went ahead and burned the disc, let's say with Nero?

    I watched 2 movies a friend had (excellent quality), which in PowerDVD under informtion are listed as PAL, yet they play fine in my JVC standalone which does not play PAL DVD's.
     
  20. tdfuller

    tdfuller Member

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    Well, the movie then would be encoded in its original video signal, in this case PAL. Then, it is up to your DVD player if it will recognize PAL/NTSC. Pretty much all software DVD players on computers automatically decode PAL/NTSC signals to display properly on your computer. However, to play on your home TV, it is up to the DVD unit attached to your DVD. Only some models can play both PAL and NTSC.
     

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