Merge "Replace hard-coded 3 by FCC_2 to simplify searches"

Author: gkasten

services/audioflinger/AudioFlinger.cpp

@@ -5192,8 +5192,8 @@ bool AudioFlinger::RecordThread::checkForNewParameters_l()
                     reqFormat == mInput->stream->common.get_format(&mInput->stream->common) &&
                     reqFormat == AUDIO_FORMAT_PCM_16_BIT &&
                     ((int)mInput->stream->common.get_sample_rate(&mInput->stream->common) <= (2 * reqSamplingRate)) &&
-                    (popcount(mInput->stream->common.get_channels(&mInput->stream->common)) < 3) &&
-                    (reqChannelCount < 3)) {
+                    popcount(mInput->stream->common.get_channels(&mInput->stream->common)) <= FCC_2 &&
+                    (reqChannelCount <= FCC_2)) {
                     status = NO_ERROR;
                 }
                 if (status == NO_ERROR) {
@@ -5270,7 +5270,7 @@ void AudioFlinger::RecordThread::readInputParameters()
     mFrameCount = mInputBytes / mFrameSize;
     mRsmpInBuffer = new int16_t[mFrameCount * mChannelCount];
 
-    if (mSampleRate != mReqSampleRate && mChannelCount < 3 && mReqChannelCount < 3)
+    if (mSampleRate != mReqSampleRate && mChannelCount <= FCC_2 && mReqChannelCount <= FCC_2)
     {
         int channelCount;
          // optmization: if mono to mono, use the resampler in stereo to stereo mode to avoid
@@ -5559,7 +5559,7 @@ audio_io_handle_t AudioFlinger::openInput(uint32_t *pDevices,
     if (inStream == NULL && status == BAD_VALUE &&
         reqFormat == format && format == AUDIO_FORMAT_PCM_16_BIT &&
         (samplingRate <= 2 * reqSamplingRate) &&
-        (popcount(channels) < 3) && (popcount(reqChannels) < 3)) {
+        (popcount(channels) <= FCC_2) && (popcount(reqChannels) <= FCC_2)) {
         ALOGV("openInput() reopening with proposed sampling rate and channels");
         status = inHwDev->open_input_stream(inHwDev, *pDevices, &format,
                                             &channels, &samplingRate,

services/audioflinger/AudioFlinger.h

@@ -58,6 +58,15 @@ class AudioResampler;
 
 // ----------------------------------------------------------------------------
 
+// AudioFlinger has a hard-coded upper limit of 2 channels for capture and playback.
+// There is support for > 2 channel tracks down-mixed to 2 channel output via a down-mix effect.
+// Adding full support for > 2 channel capture or playback would require more than simply changing
+// this #define.  There is an independent hard-coded upper limit in AudioMixer;
+// removing that AudioMixer limit would be necessary but insufficient to support > 2 channels.
+// The macro FCC_2 highlights some (but not all) places where there is are 2-channel assumptions.
+// Search also for "2", "left", "right", "[0]", "[1]", ">> 16", "<< 16", etc.
+#define FCC_2 2     // FCC_2 = Fixed Channel Count 2
+
 static const nsecs_t kDefaultStandbyTimeInNsecs = seconds(3);
 
 class AudioFlinger :