サウンド_Nellymoser_圧縮 - hsk/swfspec_ja GitHub Wiki
Nellymoser 圧縮
Starting with SWF 6, a compressed sound format called Nellymoser Asao is available. This is a single-channel (mono) format optimized for low-bitrate transmission of speech. The format was developed by Nellymoser Inc. at www.nellymoser.com. A summary of the Nellymoser Asao encoding process is provided here. For full details of the Asao format, contact Nellymoser. Asao uses frequency-domain characteristics of sound for compression. Sound data is grouped into frames of 256 samples. Each frame is converted into the frequency domain and the most significant (highest-amplitude) frequencies are identified. A number of frequency bands are selected for encoding; the rest are discarded. The bitstream for each frame then encodes which frequency bands are in use and what their amplitudes are.