Allow more than 2 input channels in AudioProcessing.

webrtc/common_audio/wav_file.cc

Index: webrtc/common_audio/wav_file.cc
diff --git a/webrtc/common_audio/wav_file.cc b/webrtc/common_audio/wav_file.cc
index 995043461a18a692745ce747dab7afa4c9a8d9cf..a0c792c54a6fab246dd66afca5af860cdb53a7f8 100644
--- a/webrtc/common_audio/wav_file.cc
+++ b/webrtc/common_audio/wav_file.cc
@@ -123,11 +123,6 @@ void WavWriter::WriteSamples(const int16_t* samples, size_t num_samples) {
   num_samples_ += static_cast<uint32_t>(written);
   CHECK(written <= std::numeric_limits<uint32_t>::max() ||
         num_samples_ >= written);  // detect uint32_t overflow
-  CHECK(CheckWavParameters(num_channels_,

[aluebs-webrtc, 2015/07/14 23:12:42]

Why do you need to remove this?

[mgraczyk, 2015/07/15 01:12:45]

My comments were left behind on a previous patch.  I'll paste them here and in
the other places:

This check fails when the number of channels does not divide the buffet size. It
doesn't seem correct because we may have written a chunk that splits a frame
without writing all samples. The only thing that changes here is num_samples_
and the check happens on Close. If an invalid number of total samples have been
written, we will catch it there.

[aluebs-webrtc, 2015/07/15 18:04:05]

But do we want to write a frame without all samples? I mean, why should that
happen?

[mgraczyk, 2015/07/15 20:03:19]

The WriteSamples(float*...) passes partial frames because it uses a buffer size
that isn't necessarily a multiple of the number of channels.  

The CHECK is overly restrictive.  We want to be able to write partial frames
because there could be some buffering between the whatever module generates the
audio and this WAV writer.  The CHECK places restrictions on the buffer's output
but does not give us any additional safety on the output of the audio generator
because the buffer could pass along invalid partial frames as whole frames
anyway.  If we want to make sure we're generating whole frames, we should be
doing that somewhere else.  The WAV writer just needs to check self-consistency,
which means it should do the check when it writes to the file.

[aluebs-webrtc, 2015/07/15 21:29:16]

Ok, agreed.

-                           sample_rate_,
-                           kWavFormat,
-                           kBytesPerSample,
-                           num_samples_));
 }
 
 void WavWriter::WriteSamples(const float* samples, size_t num_samples) {