VBAN Throttle correction

pschatzmann · Oct 21, 2023 · 8089a7b · 8089a7b
1 parent e38edd7
commit 8089a7b
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Showing 4 changed files with 18 additions and 13 deletions.
diff --git a/examples/examples-communication/vban/player-sdmmc-vban/player-sdmmc-vban.ino b/examples/examples-communication/vban/player-sdmmc-vban/player-sdmmc-vban.ino
@@ -50,7 +50,7 @@ void setup() {
   cfg.stream_name = "Stream1";
   cfg.target_ip = IPAddress{192,168,1,37};
   cfg.throttle_active = true;
-  cfg.throttle_correction_ms = -20;
+  //cfg.throttle_correction_us = 0;
   if (!out.begin(cfg)) stop();
 
   // setup player

diff --git a/examples/examples-communication/vban/streams-generator-vban/streams-generator-vban.ino b/examples/examples-communication/vban/streams-generator-vban/streams-generator-vban.ino
@@ -28,7 +28,7 @@ void setup(void) {
   cfg.stream_name = "Stream1";
   cfg.target_ip = IPAddress{192,168,1,37}; 
   cfg.throttle_active = true;
-  cfg.throttle_correction_ms = -4; // optimize overload and underrun
+  //cfg.throttle_correction_us = 0; // optimize overload and underrun
   if (!out.begin(cfg)) stop();
 
   // Setup sine wave

diff --git a/src/AudioLibs/Communication.h b/src/AudioLibs/Communication.h
@@ -740,7 +740,7 @@ struct ThrottleConfig : public AudioInfo {
     bits_per_sample = 16;
     channels = 2;
   }
-  int correction_ms = 0;
+  int correction_us = 0;
 };
 
 /**
@@ -767,27 +767,33 @@ class Throttle {
   void begin(ThrottleConfig info) {
     this->info = info;
     bytesPerSample = info.bits_per_sample / 8 * info.channels;
+    startDelay();
   }
 
   // starts the timing
-  void startDelay() { start_time = millis(); }
+  void startDelay() { 
+    start_time = micros(); 
+    sum_samples = 0;
+  }
 
   // delay
   void delayBytes(size_t bytes) { delaySamples(bytes / bytesPerSample); }
 
   // delay
   void delaySamples(size_t samples) {
-    int durationMsEff = millis() - start_time;
-    int durationToBe = (samples * 1000) / info.sample_rate;
-    int waitMs = durationToBe - durationMsEff + info.correction_ms;
-    LOGI("wait: %d", waitMs);
-    if (waitMs > 0) {
-      delay(waitMs);
+    sum_samples += samples;
+    int64_t durationUsEff = micros() - start_time;
+    int64_t durationUsToBe = (sum_samples * 1000000) / info.sample_rate;
+    int64_t waitUs = durationUsToBe - durationUsEff + info.correction_us;
+    LOGI("wait: %d", waitUs);
+    if (waitUs > 0) {
+      delayMicroseconds(waitUs);
     }
   }
 
  protected:
   unsigned long start_time;
+  uint64_t sum_samples = 0;
   ThrottleConfig info;
   int bytesPerSample;
 };

diff --git a/src/AudioLibs/VBANStream.h b/src/AudioLibs/VBANStream.h
@@ -29,7 +29,7 @@ class VBANConfig : public AudioInfo {
     // set to true if samples are generated faster then sample rate
     bool throttle_active = false;
     // when negative the number of ms that are subtracted from the calculated wait time to fine tune Overload and Underruns
-    int throttle_correction_ms = -2;
+    int throttle_correction_us = 0;
     // defines the max write size
     int max_write_size = DEFAULT_BUFFER_SIZE * 2; // just good enough for 44100 stereo
 };
@@ -57,7 +57,7 @@ class VBANStream : public AudioStream {
         AudioStream::setAudioInfo(info);
         auto thc = throttle.defaultConfig();
         thc.copyFrom(info);
-        thc.correction_ms = cfg.throttle_correction_ms;;
+        thc.correction_us = cfg.throttle_correction_us;;
         throttle.begin(thc);
         if (cfg.mode==TX_MODE){
             configure_tx();
@@ -111,7 +111,6 @@ class VBANStream : public AudioStream {
                 tx_buffer.reset();
             }
         }
-        throttle.startDelay();
         return byteCount;
     }