FLVDemuxer: Support negative cts offset

yucool · Dec 24, 2017 · c109921 · c109921
1 parent 6a1274b
commit c109921
Showing 1 changed file with 19 additions and 1 deletion.
diff --git a/src/demux/flv-demuxer.js b/src/demux/flv-demuxer.js
@@ -42,6 +42,24 @@ function ReadBig32(array, index) {
             (array[index + 3]));
 }
 
+function OverflowPlus(a, b) {
+    let value = a + b;
+    if (value > 0xFFFFFFFF) {
+        value = value - 0xFFFFFFFF - 1;
+    } else if (value < 0) {
+        value = 0xFFFFFFFF + value + 1;
+    }
+    return value;
+}
+
+function ReadBigSI24FromView(v, index) {
+    let val = (v.getUint8(index) << 16)    |
+              (v.getUint8(index + 1) << 8) |
+              (v.getUint8(index + 2));
+    val = OverflowPlus(val, 0xFF800000) ^ 0xFF800000;
+    return val;
+}
+
 
 class FLVDemuxer {
 
@@ -825,7 +843,7 @@ class FLVDemuxer {
         let v = new DataView(arrayBuffer, dataOffset, dataSize);
 
         let packetType = v.getUint8(0);
-        let cts = v.getUint32(0, !le) & 0x00FFFFFF;
+        let cts = ReadBigSI24FromView(v, 1);
 
         if (packetType === 0) {  // AVCDecoderConfigurationRecord
             this._parseAVCDecoderConfigurationRecord(arrayBuffer, dataOffset + 4, dataSize - 4);