echo_frame should be initialized as frame

[matlab2000]

there's no check for apm->ProcessReverseStream(echo_frame); actually,it will return kBadSampleRateError = -7. just treat the echo_frame like frame,initialize it and the prog will run happily. the aec module will work. webrtc::AudioFrame *echo_frame = NULL; if (is_echo_cancel) { echo_frame = new webrtc::AudioFrame(); echo_frame->num_channels_ = 1; echo_frame->sample_rate_hz_ = 16000; echo_frame->samples_per_channel_ = frame->sample_rate_hz_ * frame_step / 1000.0; }