fix bad audio quality & save_to_disk example (#64)

- save_to_disk example: write raw pcm frames into a wav file

webrtc-sys/src/audio_device.cpp

@@ -16,7 +16,7 @@
 
 #include "livekit/audio_device.h"
 
-const int kBitsPerSample = 16;
+const int kBytesPerSample = 2;
 const int kSampleRate = 48000;
 const int kChannels = 2;
 const int kSamplesPer10Ms = kSampleRate / 100;
@@ -54,13 +54,14 @@ int32_t AudioDevice::Init() {
         if (playing_) {
           int64_t elapsed_time_ms = -1;
           int64_t ntp_time_ms = -1;
+          size_t n_samples_out = 0;
           void* data = data_.data();
 
           // Request the AudioData, otherwise WebRTC will ignore the packets.
           // 10ms of audio data.
-          audio_transport_->PullRenderData(kBitsPerSample, kSampleRate,
-                                           kChannels, kSamplesPer10Ms, data,
-                                           &elapsed_time_ms, &ntp_time_ms);
+          audio_transport_->NeedMorePlayData(
+              kSamplesPer10Ms, kBytesPerSample, kChannels, kSampleRate, data,
+              n_samples_out, &elapsed_time_ms, &ntp_time_ms);
         }
 
         return webrtc::TimeDelta::Millis(10);