[linux-audio-dev] Any interest in DVD-Audio?
dave at dchapman.com
Fri Mar 4 12:30:41 UTC 2005
Alfons Adriaensen wrote:
> On Mon, Feb 28, 2005 at 08:21:19PM +0000, Dave Chapman wrote:
>>As you may know, commercially authored DVD-Audio disks have three very
>>unfriendly features - encryption, watermarking and Meridian Lossless
>>Packing (MLP). I am assuming that these are some of the reasons
>>developers have not become interested in DVD-Audio.
> Probably very true. It also seems quite difficult to obtain solid
> technical info about it.
Yes, the only way to obtain technical info is to examine some disks.
But I have found a few useful links which I have collected here:
The user manuals for the commercial DVD-Audio authoring applications
(which are normally available on the web) are also very useful.
>>My aim is to produce a set of GPL'd tools to both author, "un-author",
>>and play such unencrypted, uncompressed disks, and am curious to know if
>>any other developers have an interest in this area or not.
> I would certainly be very interested as a user. As a developer I have
> no experience at all with things such as cdrecord or cdrdao, so apart
> from some knowledge on how people would want to use DVD-A for things
> like Ambisonics, I'd probably have little to contribute. BTW, a script
> based interface such for cdrdao would be fine for me, don't waste your
> time with a GUI (others will do that anyway :-).
User feedback is always useful.
However, the development that needs to be done has nothing to do with
cdrecord or cdrdao. The authoring process will be something like:
1) Create the contents of the AUDIO_TS directory using a dvd-audio
authoring tool (this is what I am in the process of writing).
2) Create a DVD-Audio compliant UDF filesystem containing that AUDIO_TS
directory. mkisofs is already capable of doing this if you pass the
order of the files using the -sort option.
3) Burn that image with your favourite DVD recording software (I use
growisofs). There is nothing special needed here, so existing software
(growisofs, cdrecord) will do the job.
The process is exactly the same as the "dvdauthor" project for DVD-Video
authoring - create the files in a directory on your hard disk using
dvdauthor, and then image/burn using mkisofs/growisofs.
> The only limitation of not using MLP would be that you can't have six
> channels at 24/96.
> BTW, do you know the exact status of MLP ? Is patented and do we know
> how it works, or is it a 'trade secret' ?
I don't know the definitive answer to that, but I'm assuming the worse -
that it's heavily patented and that the patent holders would be very
aggressive towards any attempt to produce a free encoder or decoder.
Even for 16-bit/44.1KHz stereo, MLP would be useful (to double the
playing time), but I can live without it.
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