[CELT-dev] CELT in Digital Radio Mondiale

[Feilen, Michael]

Hi Jean Marc.

Wow, that was quick! Thank you very much for the patch :-) I'll test it as soon as I get the time.

Some benefits of CRC bit-error protection: (CRC is a cyclic code with very good burst error detection and correction capabilities.)

1) With a high probability you could detect whether the whole frame is valid or not by spending a few CRC bits and sending them as overhead information.
2) You should be able to find a code which can correct around 4 burst errors with a 10 bit CRC on 32 bit of payload data (For header protection only). For optimum shortened cyclic codes see: http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=01057825
3) There is a >99% chance that the 16 bit CRC check on a 64 bit header will fail if there are bit-errors in the header block.
4) CRC is easy to implement.

Best Regards,
Michael Feilen

-----Ursprüngliche Nachricht-----
Von: Jean-Marc Valin [mailto:jean-marc.valin at usherbrooke.ca] 
Gesendet: Dienstag, 1. Juni 2010 04:02
An: Feilen, Michael
Cc: celt-dev at xiph.org
Betreff: Re: [CELT-dev] CELT in Digital Radio Mondiale

Hi Michael,

As I suspected, the bug was simple and so was the fix. I checked it in 
for the git master branch, but that is *not* compatible with release 
0.7.1. However, the patch should apply to 0.7.1:
http://git.xiph.org/?p=celt.git;a=commitdiff;h=32589cd33e166ff62d0e842a1a9407542a104e22

Let me know if that fixes the problem for you.

Cheers,

	Jean-Marc

On 10-05-31 07:38 AM, Feilen, Michael wrote:
> Dear CELT Developers,
>
> I wrote a proposal on how to integrate CELT into Digital Radio Mondiale (DRM+). The CELT codec has been integrated in the Spark transmission software and SoDiRa receiver software.
>
> Please download the proposal here:
> http://www.drm-sender.de/celt_in_drm.pdf
> Suggestions and comments are welcome!
>
> A live on-air DRM+ transmission using CELT (v.0.7.1) for audio encoding was presented on May, 27th at the Symposium in Kaiserslautern:
> http://www.drm-radio-kl.eu/symposium2010/symposium2010en.htm
>
> Although the codec delivers very good audio quality and runs stable if the bitstream is error-free, the decoder (v0.7.1) produces a segfault under Windows in case the bitstream contains bit-errors. Currently, we detect faulty frames by an additional CRC check and avoid decoding them.
> I wonder if this behavior is intentional or if it might be a bug in the codec?
>
> Thank you!
>
> Best regards,
> Michael Feilen
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