Vorbis dev - Mar 2010 - Vorbis for digital radio at low bitrates

Dear Vorbis Devteam,

My name is Michael Feilen and I've been working on Digital Radio Mondiale
(DRM) transmitters and receivers for quite a while now. DRM uses HE-AACv2 by
Dolby to encode the audio content (see
http://www.drm.org/uploads/media/es_201980v030101p.pdf - pages 23 ff). As I
think Vorbis is an excellent alternative, I'd like to implement and define
an interface for Vorbis encoded audio as unofficial amendment to the standard
and I would be grateful if one of you could help me with the integration.
The encoder requirements for DRM(+) are:
* Support for 12 kHz, 24 kHz and 48 kHz sample rates.
* A frame-format (transform length) of 960 samples per frame. At the moment, the
codec seems only to support transform lengths of powers of two (e.g. 512, 1024,
...).
* Fixed bitrates from 12 kBit/s to ~128 kBit/s.

It would be a great achievement to show the usage of an open codec this digital
radio standard!

Thank you very much!

Kind Regards,
Michael Feilen

-- 
Michael Feilen, M.Sc.
Institute for Integrated Systems (LIS) (http://www.lis.ei.tum.de)
Technische Universit?t M?nchen (TUM)
D-80290 M?nchen

Tel.: +49 (0) 89 289 23873
E-mail: michael.feilen at tum.de

On 22 March 2010 06:58, Feilen, Michael <michael.feilen at tum.de> wrote:
> My name is Michael Feilen and I've been working on Digital Radio
Mondiale (DRM) transmitters and receivers for quite a while now. DRM uses
HE-AACv2 by Dolby to encode the audio content (see
http://www.drm.org/uploads/media/es_201980v030101p.pdf - pages 23 ff). As I
think Vorbis is an excellent alternative, I'd like to implement and define
an interface for Vorbis encoded audio as unofficial amendment to the standard
and I would be grateful if one of you could help me with the integration.
Sounds great; thanks for supporting free formats!
> The encoder requirements for DRM(+) are:
> * Support for 12 kHz, 24 kHz and 48 kHz sample rates.
This is no problem, although the reference encoder is tuned for 44/48
kHz and will perform better there than at 12 kHz.
> * A frame-format (transform length) of 960 samples per frame. At the
moment, the codec seems only to support transform lengths of powers of two (e.g.
512, 1024, ...).
It's worse than that; Vorbis uses a mix of two different transform
lengths. There's no way this requirement can be met by a Vorbis
implementation. Can you explain why this is important?
> * Fixed bitrates from 12 kBit/s to ~128 kBit/s.
This is no problem. The reference encoder supports ABR/CBR output.

 -r

Feilen, Michael wrote:
> My name is Michael Feilen and I've been working on Digital Radio
Mondiale (DRM)
[...]

That's a very unfortunate acronym.


-- 
Tuomo

... Time flies when you don't know what you're doing