my patch for decode using burst_id

lonelysurfer lonelysurfer at web.de
Tue Jun 19 19:44:44 UTC 2012


AMR codec is said to have a 1 byte header.
AMR run at various bitrate 4.75, 5.15, 5.90, 6.70, 7.40, 7.95, 10.2 or
12.2 kbit/s and each bitrate provide different sized output blocks of
95, 103, 118, 134, 148, 159, 204, and 244 bits.

In the 1 byte header it's written which is the encoding bitrate of the
specific AMR 20ms encoded audio sample.
In particular the top 4 bits tell the bitrate (CMR) while the lower bits
are reserved and not used (all 0 or all 1).

*CMR*     * MODE*        *FRAME SIZE( in bytes )*
0        AMR 4.75            13
1        AMR 5.15            14
2        AMR 5.9             16
3        AMR 6.7             18
4        AMR 7.4             20
5        AMR 7.95            21
6        AMR 10.2            27
7        AMR 12.2            32

AMR Reference:
http://wiki.forum.nokia.com/index.php/AMR_format
http://wiki.forum.nokia.com/index.php/AMR_format 
http://en.wikipedia.org/wiki/Adaptive_Multi-Rate_audio_codec
http://en.wikipedia.org/wiki/Adaptive_Multi-Rate_audio_codec 


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