Merge pull request #288 from dmlap/ignore-nit2

Ignore nit2

Merge pull request #288 from dmlap/ignore-nit2
Ignore nit2
David LaPalomento
Showing 2 changed files with 76 additions and 21 deletions
src/segment-parser.js
test/segment-parser.js
--- a/src/segment-parser.js
View file @93d4e05
+++ b/src/segment-parser.js
View file @93d4e05
@@ -221,6 +221,9 @@
        patTableId, // :int
        patCurrentNextIndicator, // Boolean
        patSectionLength, // :uint
+        programNumber, // :uint
+        programPid, // :uint
+        patEntriesEnd, // :uint
        pesPacketSize, // :int,
        dataAlignmentIndicator, // :Boolean,
@@ -293,6 +296,8 @@
        if (patCurrentNextIndicator) {
          // section_length specifies the number of bytes following
          // its position to the end of this section
+          // section_length = rest of header + (n * entry length) + CRC
+          // = 5 + (n * 4) + 4
          patSectionLength =  (data[offset + 1] & 0x0F) << 8 | data[offset + 2];
          // move past the rest of the PSI header to the first program
          // map table entry
@@ -300,15 +305,22 @@
          // we don't handle streams with more than one program, so
          // raise an exception if we encounter one
-          // section_length = rest of header + (n * entry length) + CRC
+          patEntriesEnd = offset + (patSectionLength - 5 - 4);
-          // = 5 + (n * 4) + 4
+          for (; offset < patEntriesEnd; offset += 4) {
-          if ((patSectionLength - 5 - 4) / 4 !== 1) {
+            programNumber = (data[offset] << 8 | data[offset + 1]);
-            throw new Error("TS has more that 1 program");
+            programPid = (data[offset + 2] & 0x1F) << 8 | data[offset + 3];
+            // network PID program number equals 0
+            // this is primarily an artifact of EBU DVB and can be ignored
+            if (programNumber === 0) {
+              self.stream.networkPid = programPid;
+            } else if (self.stream.pmtPid === undefined) {
+              // the Program Map Table (PMT) associates the underlying
+              // video and audio streams with a unique PID
+              self.stream.pmtPid = programPid;
+            } else if (self.stream.pmtPid !== programPid) {
+              throw new Error("TS has more that 1 program");
+            }
          }
-          // the Program Map Table (PMT) associates the underlying
-          // video and audio streams with a unique PID
-          self.stream.pmtPid = (data[offset + 2] & 0x1F) << 8 | data[offset + 3];
        }
      } else if (pid === self.stream.programMapTable[STREAM_TYPES.h264] ||
                 pid === self.stream.programMapTable[STREAM_TYPES.adts] ||
@@ -425,6 +437,9 @@
          // rest of header + CRC = 9 + 4
          pmtSectionLength -= 13;
+          // capture the PID of PCR packets so we can ignore them if we see any
+          self.stream.programMapTable.pcrPid = (data[offset + 8] & 0x1f) << 8 | data[offset + 9];
          // align offset to the first entry in the PMT
          offset += 12 + pmtProgramDescriptorsLength;
@@ -461,10 +476,16 @@
          }
        }
        // We could test the CRC here to detect corruption with extra CPU cost
+      } else if (self.stream.networkPid === pid) {
+        // network information specific data (NIT) packet
      } else if (0x0011 === pid) {
        // Service Description Table
      } else if (0x1FFF === pid) {
        // NULL packet
+      } else if (self.stream.programMapTable.pcrPid) {
+        // program clock reference (PCR) PID for the primary program
+        // PTS values are sufficient to synchronize playback for us so
+        // we can safely ignore these
      } else {
        videojs.log("Unknown PID parsing TS packet: " + pid);
      }
--- a/test/segment-parser.js
View file @93d4e05
+++ b/test/segment-parser.js
View file @93d4e05
@@ -64,12 +64,15 @@
  makePmt = function(options) {
    var
      result = [],
+      pcr = options.pcr || 0,
      entryCount = 0,
      k,
      sectionLength;
    for (k in options.pids) {
-      entryCount++;
+      if (k !== 'pcr') {
+        entryCount++;
+      }
    }
    // table_id
    result.push(0x02);
@@ -88,8 +91,8 @@
    // last_section_number
    result.push(0x00);
    // reserved PCR_PID
-    result.push(0xe1);
+    result.push(0xe0 | (pcr & (0x1f << 8)));
-    result.push(0x00);
+    result.push(pcr & 0xff);
    // reserved program_info_length
    result.push(0xf0);
    result.push(0x11); // hard-coded 17 byte descriptor
@@ -121,13 +124,26 @@
  makePat = function(options) {
    var
      result = [],
+      programEntries = [],
+      sectionLength,
      k;
+    // build the program entries first
+    for (k in options.programs) {
+      // program_number
+      programEntries.push((k & 0xFF00) >>> 8);
+      programEntries.push(k & 0x00FF);
+      // reserved program_map_pid
+      programEntries.push((options.programs[k] & 0x1f00) >>> 8);
+      programEntries.push(options.programs[k] & 0xff);
+    }
+    sectionLength = programEntries.length + 5 + 4;
    // table_id
    result.push(0x00);
    // section_syntax_indicator '0' reserved section_length
-    result.push(0x80);
+    result.push(0x80 | ((0x300 & sectionLength) >>> 8));
-    result.push(0x0d); // section_length for one program
+    result.push(0xff & sectionLength); // section_length
    // transport_stream_id
    result.push(0x00);
    result.push(0x00);
@@ -137,14 +153,8 @@
    result.push(0x00);
    // last_section_number
    result.push(0x00);
-    for (k in options.programs) {
+    // program entries
-      // program_number
+    result = result.concat(programEntries);
-      result.push((k & 0xFF00) >>> 8);
-      result.push(k & 0x00FF);
-      // reserved program_map_pid
-      result.push((options.programs[k] & 0x1f00) >>> 8);
-      result.push(options.programs[k] & 0xff);
-    }
    return result;
  };
@@ -211,6 +221,30 @@
    strictEqual(parser.stream.programMapTable[adtsType], 0x03, 'audio is PID 3');
  });
+  test('ignores network information specific data (NIT) in the PAT', function() {
+    parser.parseSegmentBinaryData(new Uint8Array(makePacket({
+      programs: {
+        0x01: [0x01],
+        0x00: [0x00] // a NIT has a reserved PID of 0x00
+      }
+    })));
+    ok(true, 'did not throw when a NIT is encountered');
+  });
+  test('ignores packets with PCR pids', function() {
+    parser.parseSegmentBinaryData(new Uint8Array(makePacket({
+      programs: {
+        0x01: [0x01]
+      }
+    }).concat(makePacket({
+      pid: 0x01,
+      pcr: 0x02
+    }))));
+    equal(parser.stream.programMapTable.pcrPid, 0x02, 'parsed the PCR pid');
+  });
  test('recognizes metadata streams', function() {
    parser.parseSegmentBinaryData(new Uint8Array(makePacket({
      programs: {