Sample TWCC implementation

samples/Common.c

@@ -553,7 +553,7 @@ STATUS createSampleStreamingSession(PSampleConfiguration pSampleConfiguration, P
 
     ATOMIC_STORE_BOOL(&pSampleStreamingSession->terminateFlag, FALSE);
     ATOMIC_STORE_BOOL(&pSampleStreamingSession->candidateGatheringDone, FALSE);
-    pSampleStreamingSession->newVideoBitrate = 0;
+    MEMSET(&pSampleStreamingSession->twccMetadata, 0x00, SIZEOF(TwccMetadata));
     pSampleStreamingSession->peerConnectionMetrics.peerConnectionStats.peerConnectionStartTime = GETTIME() / HUNDREDS_OF_NANOS_IN_A_MILLISECOND;
     // Flag to enable SDK to calculate selected ice server, local, remote and candidate pair stats.
     pSampleConfiguration->enableIceStats = FALSE;
@@ -705,35 +705,40 @@ VOID sampleBandwidthEstimationHandler(UINT64 customData, DOUBLE maximumBitrate)
     DLOGV("received bitrate suggestion: %f", maximumBitrate);
 }
 
-VOID sampleSenderBandwidthEstimationHandler(UINT64 customData, UINT32 txBytes, UINT32 rxBytes, UINT32 txPacketsCnt, UINT32 rxPacketsCnt,
-                                            UINT64 duration)
-{
+void sampleSenderBandwidthEstimationHandler(UINT64 customData, UINT32 txBytes, UINT32 rxBytes, UINT32 txPacketsCnt, UINT32 rxPacketsCnt, UINT64 duration) {
     UNUSED_PARAM(duration);
-    UNUSED_PARAM(rxBytes);
-    UNUSED_PARAM(txBytes);
     UINT32 lostPacketsCnt = txPacketsCnt - rxPacketsCnt;
-    UINT32 percentLost = lostPacketsCnt * 100 / txPacketsCnt;
-    PSampleStreamingSession pSampleStreamingSession = (PSampleStreamingSession) customData;
-    UINT64 bitrate;
-    DLOGI("Percent lost: %d", percentLost);
-    if (percentLost <= 5) {
-        // increase encoder bitrate by 5 percent
-        bitrate = pSampleStreamingSession->currentVideoBitrate * 1.05f;
-    } else if (percentLost > 5) {
-        if(pSampleStreamingSession->currentVideoBitrate >= 1 * 1024) {
-            // decrease encoder bitrate by packet loss percent
-            bitrate = pSampleStreamingSession->currentVideoBitrate * (1.0f - percentLost/100.0f);
-        }
-        else {
-            DLOGW("Bitrate already too low...maintaining..expect frame packet drops and choppy playback");
-            bitrate = pSampleStreamingSession->currentVideoBitrate;
-        }
+    UINT8 percentLost = (txPacketsCnt > 0) ? (lostPacketsCnt * 100 / txPacketsCnt) : 0;
+
+    SampleStreamingSession* pSampleStreamingSession = (SampleStreamingSession*) customData;
+
+    // Calculate smoothed packet loss
+    DOUBLE currentPacketLoss = (DOUBLE) percentLost;
+    EMA_ACCUMULATOR_GET_NEXT(pSampleStreamingSession->twccMetadata.averagePacketLoss, currentPacketLoss);
+
+    UINT64 currentTimeMs = GETTIME();
+    UINT64 timeDiff = currentTimeMs - pSampleStreamingSession->twccMetadata.lastAdjustmentTimeMs;
+    if (timeDiff < ADJUSTMENT_INTERVAL_MS) {
+        // Too soon for another adjustment
+        DLOGI("Too soon");
+        return;
     }
-    if(bitrate > 2048000) {
-        bitrate = pSampleStreamingSession->currentVideoBitrate;
+
+    UINT64 bitrate = pSampleStreamingSession->twccMetadata.currentVideoBitrate;
+    if (pSampleStreamingSession->twccMetadata.averagePacketLoss <= 5) {
+        // increase encoder bitrate by 5 percent with a cap at MAX_BITRATE
+        bitrate = (UINT64) MIN(bitrate * 1.05f, MAX_BITRATE);
+    } else {
+        // decrease encoder bitrate by average packet loss percent, with a cap at MIN_BITRATE
+        bitrate = (UINT64) MAX(bitrate * (1.0f - pSampleStreamingSession->twccMetadata.averagePacketLoss / 100.0f), MIN_BITRATE);
     }
-    pSampleStreamingSession->newVideoBitrate = bitrate;
-    DLOGI("received sender bitrate estimation: suggested bitrate %u kbps sent: %u bytes %u packets received: %u bytes %u packets in %lu msec, ", bitrate,
+
+    // Update the session with the new bitrate and adjustment time
+    pSampleStreamingSession->twccMetadata.newVideoBitrate = bitrate;
+    pSampleStreamingSession->twccMetadata.lastAdjustmentTimeMs = currentTimeMs;
+
+    DLOGI("Adjustment made: average packet loss = %.2f%%, timediff: %llu ms", pSampleStreamingSession->twccMetadata.averagePacketLoss, ADJUSTMENT_INTERVAL_MS, timeDiff);
+    DLOGI("received sender bitrate estimation: suggested bitrate %u sent: %u bytes %u packets received: %u bytes %u packets in %lu msec", bitrate,
           txBytes, txPacketsCnt, rxBytes, rxPacketsCnt, duration / 10000ULL);
 }
 

samples/Samples.h

@@ -83,6 +83,11 @@ extern "C" {
 #define MAX_SIGNALING_CLIENT_METRICS_MESSAGE_SIZE 736 // strlen(SIGNALING_CLIENT_METRICS_JSON_TEMPLATE) + 20 * 10
 #define MAX_ICE_AGENT_METRICS_MESSAGE_SIZE        113 // strlen(ICE_AGENT_METRICS_JSON_TEMPLATE) + 20 * 2
 
+
+#define ADJUSTMENT_INTERVAL_MS 5 * HUNDREDS_OF_NANOS_IN_A_SECOND
+#define MIN_BITRATE 512
+#define MAX_BITRATE 2048000
+
 typedef enum {
     SAMPLE_STREAMING_VIDEO_ONLY,
     SAMPLE_STREAMING_AUDIO_VIDEO,
@@ -179,6 +184,15 @@ typedef struct {
 
 typedef VOID (*StreamSessionShutdownCallback)(UINT64, PSampleStreamingSession);
 
+typedef struct {
+    UINT64 lastAdjustmentTimeMs;
+    UINT64 currentVideoBitrate;
+    UINT64 newVideoBitrate;
+    UINT64 currentAudioBitrate;
+    UINT64 newAudioBitrate;
+    float averagePacketLoss;
+} TwccMetadata, *PTwccMetadata;
+
 struct __SampleStreamingSession {
     volatile ATOMIC_BOOL terminateFlag;
     volatile ATOMIC_BOOL candidateGatheringDone;
@@ -208,10 +222,7 @@ struct __SampleStreamingSession {
     CHAR pPeerConnectionMetricsMessage[MAX_PEER_CONNECTION_METRICS_MESSAGE_SIZE];
     CHAR pSignalingClientMetricsMessage[MAX_SIGNALING_CLIENT_METRICS_MESSAGE_SIZE];
     CHAR pIceAgentMetricsMessage[MAX_ICE_AGENT_METRICS_MESSAGE_SIZE];
-    UINT64 currentVideoBitrate;
-    UINT64 newVideoBitrate;
-    UINT64 newAudioBitrate;
-    UINT64 currentAudioBitrate;
+    TwccMetadata twccMetadata;
 };
 
 // TODO this should all be in a higher webrtccontext layer above PeerConnection

samples/kvsWebRTCClientMasterGstSample.c

@@ -67,10 +67,10 @@ GstFlowReturn on_new_sample(GstElement* sink, gpointer data, UINT64 trackid)
                 if(encoder != NULL) {
                     guint bitrate;
                     g_object_get(G_OBJECT(encoder), "bitrate", &bitrate, NULL);
-                    pSampleStreamingSession->currentVideoBitrate = (UINT64) bitrate;
-                    if(pSampleStreamingSession->newVideoBitrate != 0) {
-                        bitrate = (guint) (pSampleStreamingSession->newVideoBitrate);
-                        pSampleStreamingSession->newVideoBitrate = 0;
+                    pSampleStreamingSession->twccMetadata.currentVideoBitrate = (UINT64) bitrate;
+                    if(pSampleStreamingSession->twccMetadata.newVideoBitrate != 0) {
+                        bitrate = (guint) (pSampleStreamingSession->twccMetadata.newVideoBitrate);
+                        pSampleStreamingSession->twccMetadata.newVideoBitrate = 0;
                         g_object_set(G_OBJECT(encoder), "bitrate", bitrate, NULL);
                     }