pcm in blue-ray

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绝大多数传统视频里的pcm数据时raw data. 在视频数据里找到audio包后，直接把数据输出即可。

蓝光格式的pcm数据如下：

PES_packet_payload() {
HDMV_LPCM_audio_data_header()
HDMV_LPCM_audio_data_payload()
}

它多包含了一个个4bytes 的HDMV_LPCM_audio_data_header() 我们解码时，需去掉这个包头，输出后面的信息。

包头格式如下：

Syntax No. of bits Mnemonics
HDMV_LPCM_audio_data_header() {
audio_data_payload_size    16 uimsbf
channel_assignment                                  4 bslbf
sampling_frequency                                   4 uimsbf
bits_per_sample                                         2 uimsbf
start_flag                                                    1 bslbf
reserved                                                     5 bslbf
}

对每包audio数据都是240个样本，audio_data_payload_size大小如下：

sampling_frequency bits_per_sample number of channels audio_data_payload_size[bytes]

48 KHz 16 bit 2 960

4 1920

6 2880

8 3840

48 KHz 20bit / 24bit 2 1440

4 2880

6 4320

8 5760

96 KHz 16 bit 2 1920

4 3840

6 5760

8 7680

96 KHz 20bit / 24bit 2 2880

4 5760

6 8640

8 11520

192 KHz 16 bit 2 3840

4 7680

6 11520

192 KHz 20bit / 24bit 2 5760

4 11520

6 17280

channel_assignment:

value

0: reserved

1: 2ch, mono

2: 2ch, reserved

3: 2ch, stereo

4: 4ch, L,C,R(3/0)

5: 4ch, L,R,S(2/1)

6: 4ch, L,C,R,S(3/1)

7: 4ch, L,R,LS,RS(2/2)

8: 6ch, L,C,R,LS,RS(3/2)

9: 6ch, L,C,R,LS,RS,lfe(3/2+lfe)
10: 8ch, L,C,R,LS,CS1,CS2,RS(3/4)

11: 8ch, L,C,R,LS,CS1,CS2,RS,lfe(3/4+lfe)

12-15: reserved

sampling_frequency:

value

1: 48khz

4: 96khz

5: 192khz

others: reserved

bits_per_sample:

value

0: reserved

1: 16bits/sample

2: 20bits/sample

3: 24bits/sample

start_flag:

1-bit flag that indicates "track start" or "index point". The use of this flag is not mandatory,
and it can take over the role of the Q bit from User data defined in IEC 60958-3[49].

参考资料：System Description Blu-ray Disc Read-Only Format Part 3 Audio Visual Basic Specifications Version 0.99rev2