Open ALSA device using hw_params calls

Replaced using ALSA snd_pcm_set_params() with separate snd_pcm_hw_X() calls in order to use snd_pcm_hw_params_set_rate_near() which allows for setting rates on some devices that don't normally allow some rates like 22050Hz.

BUG=chromium-os:13231, chromium-os:13721
TEST=Manual, 22khz audio should play (test file in bug)

Review URL: http://codereview.chromium.org/6869037

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@82042 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 72 insertions, 4 deletions

diff --git a/media/audio/linux/alsa_wrapper.cc b/media/audio/linux/alsa_wrapper.cc
index 8270430..563bccb 100644
--- a/media/audio/linux/alsa_wrapper.cc
+++ b/media/audio/linux/alsa_wrapper.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -65,12 +65,76 @@ const char* AlsaWrapper::PcmName(snd_pcm_t* handle) {
   return snd_pcm_name(handle);
 }
 
+int AlsaWrapper::ConfigureHwParams(snd_pcm_t* handle,
+                                   snd_pcm_hw_params_t* hw_params,
+                                   snd_pcm_format_t format,
+                                   snd_pcm_access_t access,
+                                   unsigned int channels,
+                                   unsigned int rate,
+                                   int soft_resample,
+                                   unsigned int latency) {
+  int err = 0;
+  if ((err = snd_pcm_hw_params_any(handle, hw_params)) < 0)
+    return err;
+
+  if ((err = snd_pcm_hw_params_set_rate_resample(handle, hw_params,
+                                                 soft_resample)) < 0) {
+    return err;
+  }
+
+  if ((err = snd_pcm_hw_params_set_format(handle, hw_params, format)) < 0)
+    return err;
+
+  int dir = 0;
+  unsigned new_rate = rate;
+  if ((err = snd_pcm_hw_params_set_rate_near(handle, hw_params,
+                                             &new_rate, &dir)) < 0) {
+    return err;
+  }
+
+  if ((err = snd_pcm_hw_params_set_access(handle, hw_params, access)) < 0)
+    return err;
+
+  if ((err = snd_pcm_hw_params_set_channels(handle, hw_params, channels)) < 0)
+    return err;
+
+  unsigned buffer_time = latency;
+  if (buffer_time == 0) {
+    if ((err = snd_pcm_hw_params_get_buffer_time_max(hw_params,
+                                                      &buffer_time, 0)) < 0) {
+      return err;
+    }
+    if (buffer_time > 500000)
+      buffer_time = 500000;
+  }
+
+  unsigned period_time = buffer_time / 4;
+  if ((err = snd_pcm_hw_params_set_period_time_near(handle, hw_params,
+                                                    &period_time, 0)) < 0) {
+    return err;
+  }
+
+  err = snd_pcm_hw_params_set_buffer_time_near(handle, hw_params,
+                                                &buffer_time, 0);
+  return err;
+}
+
 int AlsaWrapper::PcmSetParams(snd_pcm_t* handle, snd_pcm_format_t format,
                               snd_pcm_access_t access, unsigned int channels,
                               unsigned int rate, int soft_resample,
                               unsigned int latency) {
-  return snd_pcm_set_params(handle, format, access, channels, rate,
-                            soft_resample, latency);
+  int err = 0;
+  snd_pcm_hw_params_t *hw_params;
+  if ((err = snd_pcm_hw_params_malloc(&hw_params)) < 0)
+    return err;
+
+  if ((err = ConfigureHwParams(handle, hw_params, format, access, channels,
+                               rate, soft_resample, latency)) >= 0) {
+    err = snd_pcm_hw_params(handle, hw_params);
+  }
+
+  snd_pcm_hw_params_free(hw_params);
+  return err;
 }
 
 int AlsaWrapper::PcmGetParams(snd_pcm_t* handle, snd_pcm_uframes_t* buffer_size,
diff --git a/media/audio/linux/alsa_wrapper.h b/media/audio/linux/alsa_wrapper.h
index 88bdb5a..1fe1992 100644
--- a/media/audio/linux/alsa_wrapper.h
+++ b/media/audio/linux/alsa_wrapper.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
@@ -46,5 +46,9 @@ class AlsaWrapper {
   virtual const char* StrError(int errnum);
 
  private:
+  int ConfigureHwParams(snd_pcm_t* handle, snd_pcm_hw_params_t* hw_params,
+                        snd_pcm_format_t format, snd_pcm_access_t access,
+                        unsigned int channels, unsigned int rate,
+                        int soft_resample, unsigned int latency);
   DISALLOW_COPY_AND_ASSIGN(AlsaWrapper);
 };