dmazzoni's fixes to ALSA for speech_synthesis

linux/audio_output_alsa.cc

Index: linux/audio_output_alsa.cc
diff --git a/linux/audio_output_alsa.cc b/linux/audio_output_alsa.cc
index dc763ba46024157c64509916161204e043e12c5a..fdf4c6e811c63c7b0c6aea49fa17b7f7662fe98b 100644
--- a/linux/audio_output_alsa.cc
+++ b/linux/audio_output_alsa.cc
@@ -13,6 +13,57 @@
 #include "log.h"
 #include "threading.h"
 
+namespace {
+
+bool isDeviceReady() {
+  snd_ctl_card_info_t *card_info;
+  snd_ctl_card_info_alloca(&card_info);
+
+  snd_pcm_info_t *pcm_info;
+  snd_pcm_info_alloca(&pcm_info);
+
+  int valid_playback_devices = 0;
+  int card_index = -1;
+
+  while(snd_card_next(&card_index) == 0 && card_index >= 0) {
+    char card_name[20];
+    snprintf(card_name, sizeof(card_name), "hw:%d", card_index);
+    LOG(INFO) << "Checking ALSA sound card " << card_name;
+
+    snd_ctl_t *ctl;
+    if(snd_ctl_open(&ctl, card_name, 0) < 0)
+      continue;
+
+    snd_ctl_card_info(ctl, card_info);
+
+    int dev_index = -1;
+    while (snd_ctl_pcm_next_device(ctl, &dev_index) == 0 && dev_index >= 0) {
+      char device_name[30];
+      snprintf(device_name, sizeof(device_name),
+               "hw:%d,%d", card_index, dev_index);
+      LOG(INFO) << "Checking ALSA sound device " << device_name;
+
+      /* Obtain info about this particular device */
+      snd_pcm_info_set_device(pcm_info, dev_index);
+      snd_pcm_info_set_subdevice(pcm_info, 0);
+      snd_pcm_info_set_stream(pcm_info, SND_PCM_STREAM_PLAYBACK);
+      if (snd_ctl_pcm_info(ctl, pcm_info) >= 0) {
+        LOG(INFO) << "    Valid playback device: " << device_name;
+        valid_playback_devices++;
+      }
+    }
+    snd_ctl_close(ctl);
+  }
+
+  LOG(INFO) << "Total valid playback devices: " << valid_playback_devices;
+  if (valid_playback_devices == 0) {
+    return false;
+  }
+  return true;
+}
+
+}
+
 namespace speech_synthesis {
 
 class LinuxAlsaAudioOutput : public AudioOutput, public Runnable {
@@ -32,93 +83,44 @@ class LinuxAlsaAudioOutput : public AudioOutput, public Runnable {
       return true;
     }
 
+    if (!isDeviceReady()) {
+      return false;
+    }
+    
     int err;
     if ((err = snd_pcm_open(&pcm_out_handle_,
-                            "plughw:0,0",
+                            "default",
                             SND_PCM_STREAM_PLAYBACK,
                             0)) < 0) {
       LOG(INFO) << "Can't open wave output: " << snd_strerror(err) << "\n";
       return false;
     }
 
-    snd_pcm_hw_params_t *hw_params;
-    if ((err = snd_pcm_hw_params_malloc(&hw_params)) < 0) {
-      LOG(INFO) << "Can't alloc sound hardware struct " <<
-          snd_strerror(err) << "\n";
-      return false;
-    }
-
-    if ((err = snd_pcm_hw_params_any(pcm_out_handle_, hw_params)) < 0) {
-      LOG(INFO) << "Can't init sound hardware struct: " <<
-          snd_strerror(err) << "\n";
-      return false;
-    }
-
-    if ((err = snd_pcm_hw_params_set_access(
-            pcm_out_handle_, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED)) < 0) {
-      LOG(INFO) << "Can't set access: " << snd_strerror(err) << "\n";
-      return false;
-    }
-
-    if ((err = snd_pcm_hw_params_set_format(pcm_out_handle_,
-                                            hw_params,
-                                            SND_PCM_FORMAT_S16_LE)) < 0) {
-      LOG(INFO) << "Can't set 16-bit: " << snd_strerror(err) << "\n";
-      return false;
-    }
-
-    if ((err = snd_pcm_hw_params_set_rate(pcm_out_handle_,
-                                          hw_params,
-                                          44100,
-                                          0)) < 0) {
-      LOG(INFO) << "Can't set rate to 44100: " << snd_strerror(err) << "\n";
-      return false;
-    }
-
-    if ((err = snd_pcm_hw_params_set_channels(pcm_out_handle_,
-                                              hw_params,
-                                              1)) < 0) {
-      LOG(INFO) << "Can't set channels to 1: " << snd_strerror(err) << "\n";
-      return false;
-    }
-
-    int dir = 0;
-    snd_pcm_uframes_t desired_period = 512;
-    if ((err = snd_pcm_hw_params_set_period_size_near(
-            pcm_out_handle_, hw_params, &desired_period, &dir)) < 0) {
-      LOG(INFO) << "Can't set period size: " << snd_strerror(err) << "\n";
+    sample_rate_ = 44100;
+    channel_count_ = 1;
+    int soft_resample = 1;
+    unsigned int latency_us = 50000;
+    if ((err = snd_pcm_set_params(pcm_out_handle_,
+                                  SND_PCM_FORMAT_S16_LE,
+                                  SND_PCM_ACCESS_RW_INTERLEAVED,
+                                  channel_count_,
+                                  sample_rate_,
+                                  soft_resample,
+                                  latency_us)) < 0) {
+      LOG(INFO) << "Can't set pcm parameters " << snd_strerror(err);
       return false;
     }
 
-    snd_pcm_uframes_t period_size;
-    snd_pcm_hw_params_get_period_size(hw_params, &period_size, &dir);
-    chunk_size_ = static_cast<int>(period_size);
-
-    snd_pcm_uframes_t desired_buffer_size = period_size * 4;
-    if ((err = snd_pcm_hw_params_set_buffer_size(
-            pcm_out_handle_, hw_params, desired_buffer_size)) < 0) {
-      LOG(INFO) << "Can't set buffer size: " << snd_strerror(err) << "\n";
-      return false;
-    }
-
-    snd_pcm_uframes_t buffer_size;
-    snd_pcm_hw_params_get_buffer_size(hw_params, &buffer_size);
-    total_buffer_size_ = static_cast<int>(buffer_size);
-
-    unsigned int rate;
-    snd_pcm_hw_params_get_rate(hw_params, &rate, &dir);
-    sample_rate_ = rate;
-
-    unsigned int channels;
-    snd_pcm_hw_params_get_channels(hw_params, &channels);
-    channel_count_ = channels;
-
-    if ((err = snd_pcm_hw_params(pcm_out_handle_, hw_params)) < 0) {
-      LOG(INFO) << "Can't set hardware params: " << snd_strerror(err) << "\n";
+    snd_pcm_uframes_t buffer_size = 0;
+    snd_pcm_uframes_t period_size = 0;
+    if ((err = snd_pcm_get_params(pcm_out_handle_, &buffer_size, &period_size))
+        < 0) {
+      LOG(INFO) << "Can't get pcm parameters: " << snd_strerror(err);
       return false;
     }
 
-    snd_pcm_hw_params_free(hw_params);
+    chunk_size_ = period_size;
+    total_buffer_size_ = buffer_size;
 
     if ((err = snd_pcm_prepare(pcm_out_handle_)) < 0) {
       LOG(INFO) << "Can't prepare: " << snd_strerror(err) << "\n";
@@ -185,7 +187,11 @@ class LinuxAlsaAudioOutput : public AudioOutput, public Runnable {
                                static_cast<snd_pcm_uframes_t>(chunk_size));
       if (err < 0) {
         LOG(INFO) << "Write error: " << err << snd_strerror(err) << "\n";
-        return;
+        do {
+          sleep(1);
+          LOG(INFO) << "Attempting to recover audio";
+        } while (keep_running_ &&
+                 0 != snd_pcm_recover(pcm_out_handle_, err, 0));
       }
     }