Keep track of the user-facing number of channels in a ChannelBuffer

webrtc/common_audio/channel_buffer.cc

Index: webrtc/common_audio/channel_buffer.cc
diff --git a/webrtc/common_audio/channel_buffer.cc b/webrtc/common_audio/channel_buffer.cc
index 349d4245ccdb6e472db3cb60ee3a951c1e333b3b..b69491daa2d5b0f1cc907f75183a9b5be286381d 100644
--- a/webrtc/common_audio/channel_buffer.cc
+++ b/webrtc/common_audio/channel_buffer.cc
@@ -54,6 +54,7 @@ void IFChannelBuffer::RefreshF() const {
         float_channels[i][j] = int_channels[i][j];
       }
     }
+    fbuf_.set_num_channels(ibuf_.num_channels());

[peah-webrtc, 2016/06/23 13:32:21]

Would it be possible to move this before the copy? As it is now, the DCHECK for
the valid number of channels that occurs inside set_num_channels will happen
after the sample copy, which means that the DCHECK does not properly protect
agains incorrect buffer usage.

[aluebs-webrtc, 2016/06/24 02:49:16]

Good point, although it should never happen. Done.

     fvalid_ = true;
   }
 }
@@ -63,11 +64,12 @@ void IFChannelBuffer::RefreshI() const {
     RTC_DCHECK(fvalid_);
     int16_t* const* int_channels = ibuf_.channels();
     const float* const* float_channels = fbuf_.channels();
-    for (size_t i = 0; i < ibuf_.num_channels(); ++i) {
+    for (size_t i = 0; i < fbuf_.num_channels(); ++i) {
       FloatS16ToS16(float_channels[i],
                     ibuf_.num_frames(),
                     int_channels[i]);
     }
+    ibuf_.set_num_channels(fbuf_.num_channels());

[peah-webrtc, 2016/06/23 13:32:21]

Would it be possible to move this before the copy? As it is now, the DCHECK for
the valid number of channels that occurs inside set_num_channels will happen
after the sample copy, which means that the DCHECK does not properly protect
agains incorrect buffer usage.

[aluebs-webrtc, 2016/06/24 02:49:16]

Good point, although it should never happen. Done.

     ivalid_ = true;
   }
 }