Difference between revisions of "RealAudio cook"

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for multichannel data there may be additional four bytes:
for multichannel data there may be additional four bytes:
   bytes 16-19  channel mask
   bytes 16-19  channel mask
== Frame organisation ==
In case of multichannel audio frame data may consist of several subpackets (for 5.1 it's usually 4 subpackets). In this case sizes in 16-bit words for subpackets 1-N are stored as bytes at the end of frame data.
Subpacket data is XORed with <code>0x37 0xC5 0x11 0xF2</code>.


[[Category:Audio Codecs]]
[[Category:Audio Codecs]]
[[Category: MDCT Audio Codecs]]
[[Category: MDCT Audio Codecs]]
[[Category: Multichannel Audio Codecs]]
[[Category: Multichannel Audio Codecs]]

Revision as of 02:52, 11 July 2012

RealAudio cook (a.k.a. Cooker a.k.a. gecko) is an audio codec created by Real. It features different coding modes.

Cook Flavors

00  8 Kbps Music - RealAudio
01  11 Kbps Music - RealAudio
02  16 Kbps Music - RealAudio
03  20 Kbps Music - RealAudio
04  32 Kbps Music - RealAudio
05  44 Kbps Music - RealAudio
06  64 Kbps Music - RealAudio
07  32 Kbps - RealAudio
08  6 Kbps Music - RealAudio
09  20 Kbps Stereo Music
10  32 Kbps Stereo Music
11  44 Kbps Stereo Music
12  64 Kbps Stereo Music
13  96 Kbps Stereo Music
14  64 Kbps - RealAudio
15  20 Kbps Music High Response - RealAudio
16  32 Kbps Music High Response - RealAudio
17  16 Kbps Stereo Music - RealAudio
18  20 Kbps Stereo Music - RealAudio
19  20 Kbps Stereo Music High Response - RealAudio
20  32 Kbps Stereo Music - RealAudio
21  32 Kbps Stereo Music High Response - RealAudio
22  44 Kbps Stereo Music - RealAudio
23  44 Kbps Stereo Music High Response - RealAudio
24  64 Kbps Stereo Music - RealAudio
25  96 Kbps Stereo Music - RealAudio
26  12 Kbps Stereo Music - RealAudio
27  64 kbps Stereo Surround - RealAudio
28  96 kbps Stereo Surround - RealAudio
29  44 kbps Stereo Surround - RealAudio
30  96 Kbps 5.1 Multichannel - RealAudio 10
31  132 Kbps 5.1 Multichannel - RealAudio 10
32  184 Kbps 5.1 Multichannel - RealAudio 10
33  268 Kbps 5.1 Multichannel - RealAudio 10

Type Specific Data

Cook data is encapsulated in RealMedia files which transport type specific data needed by different codecs. Cook requires 8 bytes of type specific data for monophonic audio and 16 bytes for stereo data. Multi-byte numbers are big-endian:

mono and stereo data:

 bytes 0-3    Cook version
 bytes 4-5    samples per frame per channel
 bytes 6-7    number of subbands used in the frequency domain

stereo data requires 8 more bytes:

 bytes 8-11   unused
 bytes 12-13  joint stereo subband start
 bytes 14-15  joint stereo VLC bits

for multichannel data there may be additional four bytes:

 bytes 16-19  channel mask

Frame organisation

In case of multichannel audio frame data may consist of several subpackets (for 5.1 it's usually 4 subpackets). In this case sizes in 16-bit words for subpackets 1-N are stored as bytes at the end of frame data.

Subpacket data is XORed with 0x37 0xC5 0x11 0xF2.