Merge pull request #73 from jj1bdx/latency-check

Set PortAudio default latency time to 40ms
jj1bdx · Mar 8, 2024 · 8a22d1b · 8a22d1b
2 parents 0b46bec + 1d31577
commit 8a22d1b
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diff --git a/include/AudioOutput.h b/include/AudioOutput.h
@@ -98,6 +98,18 @@ class SndfileOutput : public AudioOutput {
 
 class PortAudioOutput : public AudioOutput {
 public:
+ // Static variables.
+
+ // Minimum latency for audio output in seconds
+
+ // Values of m_outputparams.suggestedLatency from PortAudio:
+ // Mac mini 2023 with macOS 14.3.1: 0.014717
+ // Ubuntu 22.04.4 on x86_64: 0.034830
+ // Kenji's experiments show that
+ // 40ms (0.04) is sufficient for macOS, Ubuntu, and Raspberry Pi OS
+
+ static constexpr PaTime minimum_latency = 0.04;
+
  //
  // Construct PortAudio output stream.
  //

diff --git a/sfmbase/AudioOutput.cpp b/sfmbase/AudioOutput.cpp
@@ -164,6 +164,13 @@ PortAudioOutput::PortAudioOutput(const PaDeviceIndex device_index,
  Pa_GetDeviceInfo(m_outputparams.device)->defaultHighOutputLatency;
  m_outputparams.hostApiSpecificStreamInfo = NULL;
 
+ // Guarantee minimum latency.
+ if (m_outputparams.suggestedLatency < minimum_latency) {
+ m_outputparams.suggestedLatency = minimum_latency;
+ }
+
+ fprintf(stderr, "suggestedLatency = %f\n", m_outputparams.suggestedLatency);
+
  m_paerror =
  Pa_OpenStream(&m_stream,
  NULL, // no input