MPEG-21 File Format support for VLC

[MyKey_]

Hi all,

I have developed a module for the support of the MPEG-21 File Format (*.mp21, *.m21) for VLC as part of a master thesis.
The MPEG-21 FF is based on XML and is compatible with the MPEG-4 File Format (*.mp4, *.m4v, ...). It is not a traditional video or audio file format but rather a wrapper to structure several files (e.g., into a music album).
The VLC module for the MP21 is currently available through the Music-MP21 sourceforge project: http://sourceforge.net/projects/music-mp21/
Currently, there aren't many MP21 authoring tools out there, so the project also includes a command line authoring tool (mp21_creator).

I was thinking that this MP21 module could make a nice feature for VLC.
So I'm asking for your opinion: Should the MPEG-21 File Format be integrated into VLC?

The MP21 module is still just a proof of concept but works reliably. If it should be integrated into VLC, I would certainly contribute in refactoring and improving it. (For example, the module is currently a demux module based on the MP4 demuxer. Splitting it up into a file handler and a demuxer would be a good idea.)

Here's some more information on the MPEG-21 File Format:
The format is specified in Part 9 of the MPEG-21 standard (ISO/IEC 21000-9, http://www.iso.org/iso/catalogue_detail ... mber=40639). It allows structuring multiple files, unambiguously identifying them, describing them, and some other fancy stuff (processing, reporting, automated selection mechanisms, adaptation, etc. - things that I have not implemented). A perfect use case is a music album in a single file, similar to iTunes LP (http://www.apple.com/itunes/lp-and-extras/). But iTunes LP is a proprietary format and is basically a web site with JavaScript that can play music. In contrast, MP21 is standardised and interoperable (e.g., a program can simply extract the lyrics for a song or other metadata).

One more note on my command line authoring tool for MP21 files (mp21_creator): it is cumbersome to use and I hope that better authoring tools will emerge eventually.

Please let me know if the MP21 module should be integrated into VLC and also whether anyone is willing to contribute some development efforts into this (I have a full-time job and can't do it alone in reasonable time).

Best regards,
MyKey_

[Jean-Baptiste Kempf]

So I'm asking for your opinion: Should the MPEG-21 File Format be integrated into VLC?

Yes.

I am not well at ease with the DRM in MPEG-21, but I believe the answer is yes.

[MyKey_]

Dear Jean-Baptiste, Dear all,

Thanks for your interest.
My MP21 module does not support DRM. The module can only play DRM-free MP21 files and from my point of view, that's okay. As the MPEG-21 standards family is quite large, it is unlikely to support all features right from the start. Currently, I aim for the support of
- Part 2: Digital Item Declaration;
- Part 3: Digital Item Identification;
- Part 9: File Format;
- Part 17: Fragment Identification.

Other features were outside the scope of my module but could be integrated into VLC later on, e.g.,
- Part 7: Digital Item Adaptation;
- Part 10: Digital Item Processing and C++ Bindings;
- Part 15: Event Reporting;
- Part 18: Digital Item Streaming.

Let me explain why I have never considered supporting DRM in the MP21 module: I see no way that DRM models such as pay-per-view could ever properly work in VLC.
Pay-per-view usually works as follows:
1) The client downloads the encrypted content.
2) The client buys a license that allows him to play the encrypted content.
3) This license contains a decryption key. The media player decrypts the content with the supplied decryption key and plays the decrypted content.
4) Once the playback has finished, it is impossible for the client to play the content again using the same license. The client has to buy another license to play the content again.
In VLC for step 3, the decryption module would send the unencrypted content to the output module. Thus, an attacker could simply rewrite the output module to work as an e.g. MP3 encoder. The content would be decrypted and stored as MP3. DRM systems prevent such attacks by using a trusted platform that couples decryption and output together with no public interface between them, so that no other software can interfere. This is either done in hardware or through proprietary software.
Please correct me if I'm wrong, but I think that even if someone wanted to fully implement DRM in VLC, it would be inherently difficult.
To conclude, I suggest to leave DRM out of the game.

A presentation with an introduction to the Music-MP21 project and a description of the MP21 module can be found at http://www.slideshare.net/mgrafl/modell ... le-formats.

Best regards,
MyKey_

[Jean-Baptiste Kempf]

Great. Now tell me why we wouldn't want this work in VLC ?

[MyKey_]

So, who is willing to help me out on the programming and refactoring tasks?

As I've already mentioned, the MP21 module is currently just a proof of concept; and with my full-time job, I only have little time for this project. Plus, a fresh pair of eyes on the code wouldn't hurt.

[Jean-Baptiste Kempf]

Well, send the current patch to vlc-devel and cry for help.

[ivoire]

Send the patch (using git-format-patch) to vlc-devel@ (videolan.org)