bpcm_specs.txt

BPCM Stream structure - BPCM VERSION: 2
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This version range supports only 16 bit sampling input in INTEL little endian (in VLC called s16l)!

SYNC
BYTE: 0xB1 - Implies Version 2

FRAME STRUCTURE
Two zeros = one byte, so 00 | 00 = word (16 bit) and 00 | 00 | 00 24 bit word so 3 bytes:
SYNC | INFO | nSamples *1  | DATA-LEN     | DATA*2 ----------------------->
B1   | 00   | 00 | 00      | 00 | ?? | ?? | [BINARY COMPRESSED AUDIO DATA]

*1 only when we need to set a block size
*2: only when data available, the datatype varies between 1 and 3 bytes
   On a silent frame it contains a double value after the info byte!
   (BZIP2 = 8, LZMA = 16 and arithmetic = 24 bit) with the sample count.
   In case compression is none, this frame is rejected!

== INFO BYTE ==
BIT 12 = data available? (see table)
BIT 34 = compression type (see table)
BIT 5  = channel config: 0=mono, 1=stereo
BIT 6  = use last blocksize: 0=use given (*1 is written) 1=use last
BIT 78 = sampling clock (see table)

data address table
00 0 = No data / silence
01 1 = 8 bit data length addressing
10 2 = 16 bit data length addressing
11 3 = 24 bit data length addressing

compression type table
00 0 = none
01 1 = BZIP2
10 2 = LZMA
11 3 = arithmetic order0

sampling clock table:
00 0 =  44100 Hz
01 1 =  48000 Hz
10 2 =  32000 Hz
11 3 =  24000 Hz