Re: [linux-minidisc] Minidisc - Upload and conversion of atrac3plus [fwd: jan.olav@ramson.org]

[Adrian Glaubitz <glaubitz@physik.fu-berlin.de>]

Hi Jan,

> 
> Hello,
> 
> thank you very much for your work to create an open alternative for using
> MiniDiscs. I have many recordings that I am eager to transfer and decode
> -> encode, and have a few question that I could not find in the faq.
> 

Thanks for using our software :).

> I have the following devices:
> 
> MZ-RH1
> MZ-R50
> MZ-R55
> 

The MZ-RH1 is the only one of the aforementioned Walkman which can
actually be connected to a PC over USB, thus it's the only one which
can be used with our software. However, tracks recorded with the
MZ-R50 and 55 can easily transfered to the PC with our software. I
will explain later on.

> 1.
> MZ-RH1 (Hi-LP/Hi-SP): Uploading works fine and produces .oma files.

Ok, this means that the tracks are not protected. This means they were
recorded with the MZ-RH1 and are thus encrypted with a constant key
only. We know this key and we can therefore decrypt these tracks. If
the tracks were recorded with another HiMD device, the encryption key
would be unknown and thus we are not (yet) able to decrypt the tracks
because our software does not yet support tracks recorded with what we
call "strong" encryption.

> However, when I import these files into SonicStage for conversion to wav,
> SonicStage states that some of the files are protected and refuses
> to convert them.

This is strange. These were recorded in ATRAC3+, right? SonicStage
should be able to read them. The only scenario I could think of is
that our software somehow messed with the file format so that the
.oma-files appear broken to SonicStage.

> In other words, some files import and convert just fine,
> while others get imported (and can be played), but cannot be converted
> (making them essentially useless). I have so far not been able to identify
> any differences that would explain why some files are marked as protected
> while others are not.
> 

Hmm, I don't see a reason why SonicStage would refuse to convert
them. Were all of these tracks recorded with the MZ-RH1 recorder?

> iii) Is there an atrac3plus decoder available for GNU/Linux (for tracks
> that are not encrypted).
> 

No, there is no decoder yet! However, there are working decoders for
ATRAC3 and ATRAC-SP (the original ATRAC-format, which your MZ-R
recorders use for example). However, reverse-engineering of ATRAC3+
has already been initiated and the ffmpeg-guys who implemented
ATRAC-SP for Linux (and other operating systems) are already looking
to implement ATRAC3+ for ffmpeg and thus Linux. It's just a matter of
time, ressources are very limited, unfortunately.

> 2.
> MZ-R50 and MZ-R55 (SP-Mono/SP-Stereo): Using lsmd.py all tracks lists as
> unprotected. Uploading with upload.py works fine and produces .aea files.
> However, using FFmpeg (version SVN-r22323), only a few tracks are
> identified as atrac1 (most cannot be identified as such, even though the
> format is the same, e.g. some SP-Mono tracks can be identified as such,
> while others cannot):
> (...)
> i) Do you know if this is a problem with ffmpeg?

Ah, this is something which Benjamin Larsson should look into. He is
the guy who developed this codec together with other guys and he
should know best.

> Please find four samples attached, SP-Mono and SP-Stereo recorded on the
> MZ-R50 and MZ-R55, respectively.

Thanks, I think these will help best when debugging the problem. As I
said, Benjamin will be the right guy to check (I hope he won't be
upset now that I'm, blaiming him ;)).

> 3)
> I am interested in learning more about the MiniDisc and would be grateful
> if I could have a user account for the wiki, enabling me to read all of
> the contents.
> 

No problem, I will send one to this email, is this ok?

> Once again, thank you for the great work done so far!

You're welcome. Thanks for using our software!

PS: Please join the mailing list to stay tuned for updates.

Adrian