Support floating-point audio output for Linux

media/audio/pulse/pulse_output.cc

Index: media/audio/pulse/pulse_output.cc
diff --git a/media/audio/pulse/pulse_output.cc b/media/audio/pulse/pulse_output.cc
index f86860571a03fca4390c4149704888b5c3630d55..76a4bd66750ee49ba20aee4da0df5c554ffac77a 100644
--- a/media/audio/pulse/pulse_output.cc
+++ b/media/audio/pulse/pulse_output.cc
@@ -12,6 +12,7 @@
 #include "media/audio/audio_device_description.h"
 #include "media/audio/audio_manager_base.h"
 #include "media/audio/pulse/pulse_util.h"
+#include "media/base/audio_sample_types.h"
 
 namespace media {
 
@@ -43,7 +44,14 @@ void PulseAudioOutputStream::StreamRequestCallback(pa_stream* s, size_t len,
 PulseAudioOutputStream::PulseAudioOutputStream(const AudioParameters& params,
                                                const std::string& device_id,
                                                AudioManagerBase* manager)
-    : params_(params),
+    : params_(AudioParameters(params.format(),
+                              params.channel_layout(),
+                              params.sample_rate(),
+                              // Ignore the given bits per sample. We
+                              // want 32 because we're outputting
+                              // floats now.

[DaleCurtis, 2016/11/01 23:07:53]

s/ now// -- no need to document the old state of the code :)

[Raymond Toy, 2016/11/01 23:18:50]

Done.

+                              32,
+                              params.frames_per_buffer())),
       device_id_(device_id),
       manager_(manager),
       pa_context_(NULL),
@@ -124,6 +132,7 @@ void PulseAudioOutputStream::FulfillWriteRequest(size_t requested_bytes) {
   while (bytes_remaining > 0) {
     void* buffer = NULL;
     size_t bytes_to_fill = params_.GetBytesPerBuffer();
+

[DaleCurtis, 2016/11/01 23:07:53]

Remove?

[Raymond Toy, 2016/11/01 23:18:50]

Done.

     CHECK_GE(pa_stream_begin_write(pa_stream_, &buffer, &bytes_to_fill), 0);
     CHECK_EQ(bytes_to_fill, static_cast<size_t>(params_.GetBytesPerBuffer()));
 
@@ -146,8 +155,13 @@ void PulseAudioOutputStream::FulfillWriteRequest(size_t requested_bytes) {
       // Note: If this ever changes to output raw float the data must be clipped
       // and sanitized since it may come from an untrusted source such as NaCl.
       audio_bus_->Scale(volume_);
-      audio_bus_->ToInterleaved(
-          audio_bus_->frames(), params_.bits_per_sample() / 8, buffer);
+
+      // Sanitize the samples.  Replace NaN with zero, and then clamp

[DaleCurtis, 2016/11/01 23:07:53]

This should already be done as part of ToInterleaved, no?

[Raymond Toy, 2016/11/01 23:18:50]

Dunno. I didn't look. I was just going by the comment in line 155.

+      // everything to the range [-1,1].
+      audio_bus_->Clamp();
+
+      audio_bus_->ToInterleaved<Float32SampleTypeTraits>(
+          audio_bus_->frames(), reinterpret_cast<float*>(buffer));
     } else {
       memset(buffer, 0, bytes_to_fill);
     }