add stream bitrate limiter to average output over time

lib/tslimit.js

@@ -40,6 +40,9 @@ function TsLimit() {
   this.pcr = -1;
   this.last = null;
 
+  this.bitrate = 10E06;
+  this.time = null;
+
   this.pcr2time = function(pcr) {
     if (self.pcr === -1) {
       self.pcr = pcr;
@@ -52,6 +55,10 @@ function TsLimit() {
     return self.last + pcr_delta;
   }
 
+  this.bytes2delta = function(bytes) {
+    return bytes*8*1E6 / self.bitrate; /* useconds */
+  }
+
   return this;
 }
 util.inherits(TsLimit, Transform);
@@ -69,13 +76,16 @@ TsLimit.prototype._transform = function(chunk, output, cb) {
     var buf = self.buffer;
     var end = buf.length-188-1;
     var now = utime();
+    if (!self.time) self.time = now;
+
+    var packet_time = self.bytes2delta(188);
     for (var i=0; i<end; i+=188) {
+      self.time += packet_time;
       var pcr = parsePCR(buf.slice(i, i+188));
-      if (pcr !== -1) {
-        var pcrtime = self.pcr2time(pcr);
-        if (pcrtime > now)
-          break;
-      }
+      if (pcr !== -1)
+        self.time = self.pcr2time(pcr);
+      if (self.time > now)
+        break;
     }
 
     // TODO: limit output speed
@@ -83,8 +93,7 @@ TsLimit.prototype._transform = function(chunk, output, cb) {
     self.buffer = buf.slice(i);
 
     if (i < end) {
-      // TODO: calculate timeout?
-      return setTimeout(process, 5);
+      return setTimeout(process, (self.time - now) / 1000);
     }
     cb();
   }