请问AAC码流中参数adts_buffer_fullness怎么计算？

你好，

  请参考：ISO/IEC 14496-3 以及 ISO/IEC 13818-7标准中的描述，希望对你有所帮助。

 adts_buffer_fullness ： state of the bit reservoir in the course of encoding the ADTS frame, up to and including the first raw_data_block() and the optionally following adts_raw_data_block_error_check(). It is transmitted as the number of available bits in the bit reservoir divided by NCC divided by 32 and truncated to an integer value (Table 9). A value of hexadecimal 7FF signals that the bitstream is a variable rate bitstream. In this case, buffer fullness is not applicable.

AAC编码器源码下面一段是关于ADTS头信息的：

A value of hexadecimal 7FF signals that the bitstream is a variable rate bitstream （VBR）。

/* Variable ADTS header */
PutBit(bitStream, 0, 1); /* copyr. id. bit */
PutBit(bitStream, 0, 1); /* copyr. id. start */
PutBit(bitStream, hEncoder->usedBytes, 13);
PutBit(bitStream, 0x7FF, 11); /* buffer fullness (0x7FF for VBR) */
PutBit(bitStream, 0, 2); /* raw data blocks (0+1=1) */

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