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

webrtc/modules/audio_processing/splitting_filter.cc

Index: webrtc/modules/audio_processing/splitting_filter.cc
diff --git a/webrtc/modules/audio_processing/splitting_filter.cc b/webrtc/modules/audio_processing/splitting_filter.cc
index e87a7f86218b9fd50c8fe109f55b128f8af7d04b..b6f642c09d4db448b320748538d485bd731d6449 100644
--- a/webrtc/modules/audio_processing/splitting_filter.cc
+++ b/webrtc/modules/audio_processing/splitting_filter.cc
@@ -72,8 +72,8 @@ void SplittingFilter::TwoBandsAnalysis(const IFChannelBuffer* data,
 
 void SplittingFilter::TwoBandsSynthesis(const IFChannelBuffer* bands,
                                         IFChannelBuffer* data) {
-  RTC_DCHECK_EQ(two_bands_states_.size(), data->num_channels());
-  for (size_t i = 0; i < two_bands_states_.size(); ++i) {
+  RTC_DCHECK_LE(data->num_channels(), two_bands_states_.size());
+  for (size_t i = 0; i < data->num_channels(); ++i) {
     WebRtcSpl_SynthesisQMF(bands->ibuf_const()->channels(0)[i],
                            bands->ibuf_const()->channels(1)[i],
                            bands->num_frames_per_band(),
@@ -95,8 +95,8 @@ void SplittingFilter::ThreeBandsAnalysis(const IFChannelBuffer* data,
 
 void SplittingFilter::ThreeBandsSynthesis(const IFChannelBuffer* bands,
                                           IFChannelBuffer* data) {
-  RTC_DCHECK_EQ(three_band_filter_banks_.size(), data->num_channels());
-  for (size_t i = 0; i < three_band_filter_banks_.size(); ++i) {
+  RTC_DCHECK_LE(data->num_channels(), three_band_filter_banks_.size());
+  for (size_t i = 0; i < data->num_channels(); ++i) {
     three_band_filter_banks_[i]->Synthesis(bands->fbuf_const()->bands(i),
                                            bands->num_frames_per_band(),
                                            data->fbuf()->channels()[i]);