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Open Source DVD-Audio project

Discussion in 'High resolution audio' started by dchapman, Mar 12, 2005.

  1. dchapman

    dchapman Member

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    I've started an open source project to develop a set of tools to author and play DVD-Audio. The project is NOT dealing with the encryption/watermarking systems or MLP, so it will not allow you to play commercial DVD-Audio discs.

    The purpose is to enable users to create high quality DVD-Audio discs containing their own recordings that will play on hardware DVD-Audio players. The specific goals are the following:

    1) Authoring of DVD-Audio discs contain uncompressed LPCM audio using any of the supported samplerates, bit-depths and channel configurations.

    2) Playback of those discs in a PC

    3) Extraction of the audio back from the DVD-Audio disc so that the MD5 checksums match those of the source audio.

    The project home page is here:

    http://dvd-audio.sourceforge.net

    I have now documented enough of the format of the files in the AUDIO_TS directory to write a basic authoring program, and that is what I am working on first. Playback and extraction will come later.

    Any contributions to the documentation on that site would be gratefully received - it doesn't have to be low-level documentation, even just high-level descriptions of the capabilities of DVD-Audio would be useful. There is a mailing list (follow the link from the above page) for discussion about the project.
     
  2. Wolfgan

    Wolfgan Member

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    Excellent initiative. I'll see what stuff can contribute to your site.
    Keep on! Wolf.
     
  3. dchapman

    dchapman Member

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    Thanks Wolfgan, hopefully you can find something useful to add to the site.

    To give a status update, my dvd-a authoring program can now generate the ATS_* files (e.g. ATS_01_0.IFO and ATS_01_1.AOB). I'm now at the bug-fixing and testing stage of that part of my program, which is by far the hardest part.

    When the ATS files are being generated reliably for all possible samplerates and word sizes, I can then add the AUDIO_TS.IFO and AUDIO_PP.IFO files, which will complete the creation of a minimal AUDIO_TS directory and then we can start authoring discs. Those two files are relatively trivial compared to the others.

    Just to give a brief roadmap, my first release will be single-group stereo only (but supporting all samplerates and word sizes) and without any still images or video menus. I will then work to add support for multi-channel sound and all 9 groups, followed by still images and video menus. Finally will be the creation of a linked video zone.

    If anyone is looking to help, then it would be very useful for someone with access to high-end commercial DVD-A Authoring applications to produce some controlled test discs for analysis. I only need the .IFO files (not the big AOB files). Contact me if you can help.

    Dave.
     
  4. Wolfgan

    Wolfgan Member

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    A close friend of mine has access to a Minnetonka DiscWelder Chhrom 2.06 installation. As far as I know he never built a dvd audio, but I may ask him to try to make a simple one to use as reference.

    I sent you a PM with my email address. Regards, Wolf
     
  5. dchapman

    dchapman Member

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    Wolfgan - thanks, I've sent you an email.

    Does anyone have access to Wavelab 5 or the Sonic DVD-A authoring program? I would be interested to see what differences there are in the discs produced by the different authoring packages.

    Dave.
     
  6. dchapman

    dchapman Member

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    I have just made the first "alpha' release of my DVD-Audio authoring program, dvda-author. It's available at:

    http://dvd-audio.sourceforge.net/alpha/

    The ZIP file contains both the source code and a pre-compiled windows executable.

    The main development platform is Linux. It should compile without problems on Mac OS X, but I haven't tested it.

    The start of a basic "how-to" is at http://dvd-audio.sourceforge.net/howto.shtml

    The current version is limited to 16-bit Stereo audio at all six DVD-Audio samplerates (44.1KHz, 48KHz, 88.2KHz, 96KHz, 176.4KHz, 192KHz), but 20/24-bit audio and multi-channel are next on my to-do list.

    For people uncomfortable with command-line programs, I am also working on a GUI version, but that's not high on my priority list at the moment.

    Dave.
     
  7. shiroh

    shiroh Guest

    woohoo loot
     
  8. vurbal

    vurbal Administrator Staff Member

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    Welcome to Afterdawn Dave! This is one of the most exciting projects I've heard about in a long time. I've been planning to put together a dedicated audio PC for making backups of my albums so I'll definitely be trying to keep up with your progress.
     
  9. dchapman

    dchapman Member

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  10. jjolson

    jjolson Member

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    A friend has Wavelab at work. I'm not sure if he's willing to make a test DVD-Audio disk, but I can ask him.
     
  11. dchapman

    dchapman Member

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    jjolson,

    Example DVD-As are always useful. Please let me know (send me a PM or email) if your friend is willing to help.

    Thanks,

    Dave.
     
  12. Yulyo

    Yulyo Member

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    Hy Dave.
    It's a great project.
    I just wanna ask you something. This will be a program to create dvd-a the CD way? I mean, it will be possible to extract the exact .wav from them, with cd text, or it will be some kind of Minetoka Chrome, Ulead, etc etc.
    I have a dvdrw at home and a lot of dvdrw discs, so if i can help you with something let me now. Right now i have Minetoka Chrome on my pc and a few other burning programs.*Nero, Ulead, Dvda Creator)
    Good luck
     
  13. dchapman

    dchapman Member

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    Yulyo,

    I'm not sure I understand your question fully, but I think the answer is yes.

    One of the main goals of my project is to take a set of WAV files, author a DVD-Audio DVD from them, and then extract identical WAV files back from the DVD. So in theory it should be better than CD (no DAE errors to worry about).

    At least initially, I will be concentrating only on the audio features of DVD-Audio. Once that is working perfectly, then I may move onto video menus, still pictures etc, but my main priority is writing a high quality audio-only authoring program.

    Thanks for your offer to help - I'll let you know if I need anything.

    Dave.
     
  14. Yulyo

    Yulyo Member

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    Hello Dave, hy everybody!
    Yes, you understood perfectly.
    That's what i'm looking for.
    So let me know if i can help.
    Have a nice day.
     
  15. vurbal

    vurbal Administrator Staff Member

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    If you're talking about extracting the audio from a commercial DVD-A there's no way to do it because of the encryption.
     
  16. Wolfgan

    Wolfgan Member

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    I have exactly the same doubt. Is it possible to extract back a 44.1KHz track to CD and use DVD-A as a backup method?

    Not talking about commercial stuff, but DVD-As I create myself with these tools (uncompressed, unprotected tracks).

    Thanks in advance for any help, Wolf.
     
  17. vurbal

    vurbal Administrator Staff Member

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    It should be possible as long as there's no encryption or compression applied. Unless my understanding is incorrect an AOB file is just a container so you should be able to extract its contents.
     
    Last edited: Apr 1, 2005
  18. Wolfgan

    Wolfgan Member

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    Thanks Vurbal. Do you happen to know how? I couldn't find any demux tool for AOBs, unless I missread Dave's description on sf.net...

    Thanks, Wolf.
     
  19. dchapman

    dchapman Member

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    Most (but not all) commercial DVD-A releases are encrypted - so the content of the AUDIO_TS folders on these DVDs can't currently be ripped, but the VIDEO_TS content (which will be either AC3 or DTS surround and/or LPCM stereo) can be ripped using any DVD-Video ripper.

    Assuming your DVD isn't encrypted, then you can access the high-res audio content. But again, there is a problem with commercial DVDs - they all use Merdian Lossless Packing (MLP) to losslessly compress the audio. MLP is a closed format, and I don't know of any decoders (but I haven't looked very hard).

    That leaves you with unencrypted DVD-As containing uncompressed LPCM audio - which is what my software and all other "affordable" (i.e. less than $5000) DVD authoring packages create.

    For these DVD-As, it would be trivial to write a program to demux the LPCM data from the AOB files. I've analysed the format of AOB files, and there is a description here:

    http://dvd-audio.sourceforge.net/spec/aob.shtml

    "LPCM in AOB" is very similar to "LPCM in VOB" (i.e. what is used on a DVD-Video disc), but there are small differences so an existing ripper won't work.

    So to conclude - yes, it is possible to rip bit-perfect uncompressed LPCM from an unencrypted DVD-A, but I don't know of any tools that can actually do it yet.

    Dave.
     
  20. jjolson

    jjolson Member

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    Commercial programs can rip unprotected DVD-Audio, Wavelab 5 can. But I don't know of any freeware program either.
     

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