28 Feb
2005
28 Feb
'05
4:24 p.m.
Hi,
Hopefully this is within the scope of this list but following a lot of
recent googling, there doesn't appear to be any interest in
"open-sourcing" anything related to DVD-Audio.
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.
However, none of those features are compulsory, and if you remove those
obstacles (which I am not interested in overcoming - simply avoiding),
you are left with a standard which allows 18 combinations of samplerate
and sample wordsize for 2-channel stereo audio (including 16-bit/44.1KHz
RedBook, and going all the way up to 24-bit/192KHz), plus a range of
6-channel uncompressed surround sound formats.
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.
To this end, I've started the "dvd-audio" project at sourceforge -
http://sourceforge.net/projects/dvd-audio/ I have not yet populated the
site with HTML content or any of the software I'm in the process of
developing, but there is a "dvd-audio-devel" mailing list which anyone
is welcome to subscribe to.
I should reiterate that I'm not interested in investigating features
such as encryption or MLP - I simply wish to be able to author my own
unencrypted and uncompressed DVD-Audio disks using my own music, which I
can then play back either on my hardware DVD-Audio player or on my PC,
all using free software
Regards,
Dave.
4 Mar
4 Mar
7:10 a.m.
On Mon, Feb 28, 2005 at 08:21:19PM +0000, Dave Chapman wrote:
Hopefully this is within the scope of this list but
following a lot of
recent googling, there doesn't appear to be any interest in
"open-sourcing" anything related to DVD-Audio.
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.
However, none of those features are compulsory, and if
you remove those
obstacles (which I am not interested in overcoming - simply avoiding),
you are left with a standard which allows 18 combinations of samplerate
and sample wordsize for 2-channel stereo audio (including 16-bit/44.1KHz
RedBook, and going all the way up to 24-bit/192KHz), plus a range of
6-channel uncompressed surround sound formats.
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 :-).
I should reiterate that I'm not interested in
investigating features
such as encryption or MLP - I simply wish to be able to author my own
unencrypted and uncompressed DVD-Audio disks using my own music, which I
can then play back either on my hardware DVD-Audio player or on my PC,
all using free software
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' ?
--
FA
8:33 a.m.
Alfons Adriaensen wrote:
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.
On Mon, Feb 28, 2005 at 08:21:19PM +0000, Dave Chapman
wrote:
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:
http://dvd-audio.sourceforge.net/links.shtml
The user manuals for the commercial DVD-Audio authoring applications
(which are normally available on the web) are also very useful.
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. 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 :-). 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.
Dave.
10:56 a.m.
Alfons Adriaensen wrote:
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 was quite sure that MLP is patented, but I couldn't find the patent.
Meridian Audio at least filed a patent application and it's licensed by
Dolby world wide.
I'm not sure if MLP could be patented in Europe for the use in software.
I wouldn't care to much about patents. AFAIK there are no legal
problems, if you distributing the sources. But I'm not lawyer. Maybe
they define MLP as copy-protection and threat you with the DMCA.
I guess the Lame guys should know. They are dealing with the same
problem, aren't they?
2:07 p.m.
On Fri, 2005-03-04 at 12:10 +0100, Alfons Adriaensen wrote:
BTW, do you know the exact status of MLP ? Is patented
and do we know
how it works, or is it a 'trade secret' ?
It's just another lossless codec like FLAC or SHN, right? Except that
it's almost certainly not as good because it won on marketing rather
than technical merit. How hard can it be?
Lee
6990
days inactive
6994
days old
linux-audio-dev@lists.linuxaudio.org
4 comments
4 participants
participants (4)
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Alfons Adriaensen -
Dave Chapman -
Lee Revell -
oliver oli