time: 2010-12-6 9:56:57
<-------主题：记录并发送的回调ph_audio_rec_cbk------->
ph_audio_rec_cbk：如需要记录到文件则record_mic_resample_stream，apply half-duples SPK driven attenuator，if (mode = SPK has priority) and SPK is active, attenuate（衰减，貌似是用于去除噪音） MIC

time: 2010-12-6 10:2:13
<-------主题：记录并发送的回调ph_audio_rec_cbk------->
ph_audio_rec_cbk：cancel acoustic echo,去除回声（do_echo_update）。处理会议ph_mediabuf_mixmedia

time: 2010-12-6 12:0:45
<-------主题：记录并发送的回调ph_audio_rec_cbk------->
ph_audio_rec_cbk：cancel acoustic echo,去除回声（do_echo_update）。处理会议ph_mediabuf_mixmedia

time: 2010-12-6 12:1:47
<-------主题：Pa_StartStream------->
声音库初始化

time: 2010-12-6 12:2:29
<-------主题：portAudio帮助文档------->
http://www.portaudio.com/trac/wiki/TutorialDir/StartStopAbort

time: 2010-12-6 15:12:15
<-------主题：CBR/ABR/VBR: the 3 encoding mode------->
LAME is able to encode your music using one of its 3 encoding modes: constant bitrate (CBR), average bitrate (ABR) and variable bitrate (VBR).

 

Constant Bitrate (CBR)
This is the default encoding mode, and also the most basic. In this mode, the bitrate will be the same for the whole file. It means that each part of your mp3 file will be using the same number of bits. The musical passage beeing a difficult one to encode or an easy one, the encoder will use the same bitrate, so the quality of your mp3 is variable. Complex parts will be of a lower quality than the easiest ones. The main advantage is that the final files size won't change and can be accurately predicted.

 

Average Bitrate (ABR)
In this mode, you choose a target bitrate and the encoder will try to constantly maintain an average bitrate while using higher bitrates for the parts of your music that need more bits. The result will be of higher quality than CBR encoding while the average file size will remain predictible, so this mode is highly recommended over CBR.

 

Variable bitrate (VBR)
In this mode, you choose the desired quality on a scale going from 9 (lowest quality/highest distortion) to 0 (highest quality/lowest distortion). Then encoder tri