Merge pull request video-dev#32 from AxelDelmas/lateLiveFix

Proposal for issue video-dev#31

API.md

@@ -176,6 +176,7 @@ configuration parameters could be provided to hls.js upon instantiation of Hls O
       maxBufferLength : 30,
       maxBufferSize : 60*1000*1000,
       liveSyncDurationCount : 3,
+      liveMaxLatencyDurationCount: 10,
       enableWorker : true,
       fragLoadingTimeOut : 20000,
       fragLoadingMaxRetry : 6,
@@ -223,6 +224,14 @@ edge of live delay, expressed in multiple of ```EXT-X-TARGETDURATION```.
 if set to 3, playback will start from fragment N-3, N being the last fragment of the live playlist.
 decreasing this value is likely to cause playback stalls.
 
+#### ```liveMaxLatencyDurationCount```
+(default Infinity)
+
+maximum delay allowed from edge of live, expressed in multiple of ```EXT-X-TARGETDURATION```.
+if set to 10, the player will seek back to ```liveSyncDurationCount``` whenever the next fragment to be loaded is older than N-10, N being the last fragment of the live playlist.
+If set, this value must be stricly superior to ```liveSyncDurationCount```
+a value too close from ```liveSyncDurationCount``` is likely to cause playback stalls.
+
 #### ```enableWorker```
 (default true)
 

src/controller/buffer-controller.js

@@ -202,9 +202,9 @@ class BufferController {
           if (levelDetails.live) {
             // check if requested position is within seekable boundaries :
             //logger.log(`start/pos/bufEnd/seeking:${start.toFixed(3)}/${pos.toFixed(3)}/${bufferEnd.toFixed(3)}/${this.video.seeking}`);
-            if (bufferEnd < start) {
+            if (bufferEnd < Math.max(start,end-this.config.liveMaxLatencyDurationCount*levelDetails.targetduration)) {
                 this.seekAfterBuffered = start + Math.max(0, levelDetails.totalduration - this.config.liveSyncDurationCount * levelDetails.targetduration);
-                logger.log(`buffer end: ${bufferEnd} is located before start of live sliding playlist, media position will be reseted to: ${this.seekAfterBuffered.toFixed(3)}`);
+                logger.log(`buffer end: ${bufferEnd} is located too far from the end of live sliding playlist, media position will be reseted to: ${this.seekAfterBuffered.toFixed(3)}`);
                 bufferEnd = this.seekAfterBuffered;
             }
             if (this.startFragmentRequested && !levelDetails.PTSKnown) {

src/hls.js

@@ -41,6 +41,7 @@ class Hls {
       maxBufferLength: 30,
       maxBufferSize: 60 * 1000 * 1000,
       liveSyncDurationCount:3,
+      liveMaxLatencyDurationCount: Infinity,
       maxMaxBufferLength: 600,
       enableWorker: true,
       fragLoadingTimeOut: 20000,
@@ -60,6 +61,11 @@ class Hls {
         if (prop in config) { continue; }
         config[prop] = configDefault[prop];
     }
+
+    if (config.liveMaxLatencyDurationCount !== undefined && config.liveMaxLatencyDurationCount <= config.liveSyncDurationCount) {
+      throw new Error('Illegal hls.js configuration: "liveMaxLatencyDurationCount" must be strictly superior to "liveSyncDurationCount" in player configuration');
+    }
+
     enableLogs(config.debug);
     this.config = config;
     // observer setup