audio policy: add fallback for output selection

When getOutputForDevice() finds a matching direct output profile
but fails to open it, try to fallback to downmix on mixer output
when format is PCM and sampling rate allows it.

Bug: 19197137.
Change-Id: I197b9b202504265b6928e69740875cb7aba5c2c5

1 files changed, 4 insertions, 0 deletions

diff --git a/services/audiopolicy/AudioPolicyManager.cpp b/services/audiopolicy/AudioPolicyManager.cpp
index fb74d66..c1c6c57 100644
--- a/services/audiopolicy/AudioPolicyManager.cpp
+++ b/services/audiopolicy/AudioPolicyManager.cpp
@@ -1098,6 +1098,10 @@ audio_io_handle_t AudioPolicyManager::getOutputForDevice(
             if (output != AUDIO_IO_HANDLE_NONE) {
                 mpClientInterface->closeOutput(output);
             }
+            // fall back to mixer output if possible when the direct output could not be open
+            if (audio_is_linear_pcm(format) && samplingRate <= MAX_MIXER_SAMPLING_RATE) {
+                goto non_direct_output;
+            }
             return AUDIO_IO_HANDLE_NONE;
         }
         outputDesc->mSamplingRate = config.sample_rate;