aaudio: fix multichannel legacy streams
Two fixes for multichannel playback over USB from
AAudio legacy streams:
1: AAudio use a channel index mask and not a positional mask
when channel count is greater than 2.
2: audio policy gives priority to an output mixer which can support
the requested channel mask without downmixing
Bug: 131685020
Test: play multichannel audio over USB
Change-Id: I13f2da48d47fcf81f522096d90ba59a89379cffb
diff --git a/media/libaaudio/src/legacy/AudioStreamTrack.cpp b/media/libaaudio/src/legacy/AudioStreamTrack.cpp
index d628bf7..094cdd1 100644
--- a/media/libaaudio/src/legacy/AudioStreamTrack.cpp
+++ b/media/libaaudio/src/legacy/AudioStreamTrack.cpp
@@ -66,7 +66,9 @@
// Use stereo if unspecified.
int32_t samplesPerFrame = (getSamplesPerFrame() == AAUDIO_UNSPECIFIED)
? 2 : getSamplesPerFrame();
- audio_channel_mask_t channelMask = audio_channel_out_mask_from_count(samplesPerFrame);
+ audio_channel_mask_t channelMask = samplesPerFrame <= 2 ?
+ audio_channel_out_mask_from_count(samplesPerFrame) :
+ audio_channel_mask_for_index_assignment_from_count(samplesPerFrame);
audio_output_flags_t flags;
aaudio_performance_mode_t perfMode = getPerformanceMode();