Rtmp AAC基本格式（转）

第一个audio data包：AAC sequence header

第二个audio data包：AAC raw

AF表示的含义：

1）第一个字节af，a就是10代表的意思是AAC，

Format of SoundData. The following values are defined:

0 = Linear PCM, platform endian

1 = ADPCM

2 = MP3

3 = Linear PCM, little endian

4 = Nellymoser 16 kHz mono

5 = Nellymoser 8 kHz mono

6 = Nellymoser

7 = G.711 A-law logarithmic PCM

8 = G.711 mu-law logarithmic PCM

9 = reserved

10 = AAC

11 = Speex

14 = MP3 8 kHz

15 = Device-specific sound

Formats 7, 8, 14, and 15 are reserved.

AAC is supported in Flash Player 9,0,115,0 and higher.

Speex is supported in Flash Player 10 and higher.

2）第一个字节中的后四位f代表如下

前2个bit的含义采样频率，这里是二进制11，代表44kHZ

Sampling rate. The following values are defined:

0 = 5.5 kHz

1 = 11 kHz

2 = 22 kHz

3 = 44 kHz

第3个bit，代表 音频用16位的

Size of each audio sample. This parameter only pertains to

uncompressed formats. Compressed formats always decode

to 16 bits internally.

0 = 8-bit samples

1 = 16-bit samples

第4个bit代表声道

Mono or stereo sound

0 = Mono sound

1 = Stereo sound

 

3）第2个字节
AACPacketType，这个字段来表示AACAUDIODATA的类型：0 = AAC sequence header，1 = AAC raw。第一个音频包用0，后面的都用1

当 AAC sequence header为0的码流结构参见“ISO-14496-3 Audio”中描述。

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