比特率：也叫码率，每秒的数据流量，同样分辨率，比特率越大，画面越清晰，压缩比越小，音质越好。文件体积也越大。

channelCount：省道数目。单声道、双声道。

sampleRate： 采样率

常见音频编码格式：

publicstaticfinalStringMIMETYPE_AUDIO_AMR_NB="audio/3gpp";publicstaticfinalStringMIMETYPE_AUDIO_AMR_WB="audio/amr-wb";publicstaticfinalStringMIMETYPE_AUDIO_MPEG="audio/mpeg";publicstaticfinalStringMIMETYPE_AUDIO_AAC="audio/mp4a-latm";publicstaticfinalStringMIMETYPE_AUDIO_QCELP="audio/qcelp";publicstaticfinalStringMIMETYPE_AUDIO_VORBIS="audio/vorbis";publicstaticfinalStringMIMETYPE_AUDIO_OPUS="audio/opus";publicstaticfinalStringMIMETYPE_AUDIO_G711_ALAW="audio/g711-alaw";publicstaticfinalStringMIMETYPE_AUDIO_G711_MLAW="audio/g711-mlaw";publicstaticfinalStringMIMETYPE_AUDIO_RAW="audio/raw";publicstaticfinalStringMIMETYPE_AUDIO_FLAC="audio/flac";publicstaticfinalStringMIMETYPE_AUDIO_MSGSM="audio/gsm";publicstaticfinalStringMIMETYPE_AUDIO_AC3="audio/ac3";publicstaticfinalStringMIMETYPE_AUDIO_EAC3="audio/eac3";