feat: add general error/warn/debug log events and log skipped adts data (#391)

Author: brandonocasey

lib/codecs/adts.js

@@ -43,6 +43,10 @@ AdtsStream = function(handlePartialSegments) {
 
   AdtsStream.prototype.init.call(this);
 
+  this.skipWarn_ = function(start, end) {
+    this.trigger('warn', {message: `adts skiping bytes ${start} to ${end} in frame ${frameNum} outside syncword`});
+  };
+
   this.push = function(packet) {
     var
       i = 0,
@@ -75,18 +79,27 @@ AdtsStream = function(handlePartialSegments) {
 
     // unpack any ADTS frames which have been fully received
     // for details on the ADTS header, see http://wiki.multimedia.cx/index.php?title=ADTS
+    var skip;
 
     // We use i + 7 here because we want to be able to parse the entire header.
     // If we don't have enough bytes to do that, then we definitely won't have a full frame.
     while ((i + 7) < buffer.length) {
       // Look for the start of an ADTS header..
       if ((buffer[i] !== 0xFF) || (buffer[i + 1] & 0xF6) !== 0xF0) {
+        if (typeof skip !== 'number') {
+          skip = i;
+        }
         // If a valid header was not found,  jump one forward and attempt to
         // find a valid ADTS header starting at the next byte
         i++;
         continue;
       }
 
+      if (typeof skip === 'number') {
+        this.skipWarn_(skip, i);
+        skip = null;
+      }
+
       // The protection skip bit tells us if we have 2 bytes of CRC data at the
       // end of the ADTS header
       protectionSkipBytes = (~buffer[i + 1] & 0x01) * 2;
@@ -128,6 +141,11 @@ AdtsStream = function(handlePartialSegments) {
       i += frameLength;
     }
 
+    if (typeof skip === 'number') {
+      this.skipWarn_(skip, i);
+      skip = null;
+    }
+
     // remove processed bytes from the buffer.
     buffer = buffer.subarray(i);
   };

lib/mp4/transmuxer.js

@@ -1099,6 +1099,7 @@ Transmuxer = function(options) {
     pipeline.coalesceStream.on('caption', this.trigger.bind(this, 'caption'));
     // Let the consumer know we have finished flushing the entire pipeline
     pipeline.coalesceStream.on('done', this.trigger.bind(this, 'done'));
+    pipeline.adtsStream.on('warn', this.trigger.bind(this, 'warn'));
   };
 
   // hook up the segment streams once track metadata is delivered