主要以视频为主,音频用webrtc内建
bool InitEncoder(int width, int height, int bitrate, CodecType codectype);
void ReleaseEncoder(int error = 0);
bool Encode(void *ydata, void *udata, void * vdata,
int ystride,int ustride, int vstride,
webrtc::EncodedImage *dst);
void ForceIntraFrame(bool);
void SetBitrate(int bitrate);
bool InitDecoder(CodecType codectype);
void ReleaseDecoder(int error = 0);
rtc::scoped_refptr<webrtc::I420Buffer> Decode(void *data, int size, uint64_t timestamp);