feat: TS parser improvements (shaka-project#4612)

dave-nicholas · Oct 25, 2022 · 5157b44 · 5157b44
1 parent 9531b07
commit 5157b44
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Showing 2 changed files with 84 additions and 6 deletions.
diff --git a/lib/util/ts_parser.js b/lib/util/ts_parser.js
@@ -23,6 +23,9 @@ shaka.util.TsParser = class {
     /** @private {boolean} */
     this.pmtParsed_ = false;
 
+    /** @private {?number} */
+    this.videoStartTime_ = null;
+
     /** @private {?number} */
     this.videoPid_ = null;
 
@@ -32,6 +35,9 @@ shaka.util.TsParser = class {
     /** @private {!Array.<Uint8Array>} */
     this.videoData_ = [];
 
+    /** @private {?number} */
+    this.audioStartTime_ = null;
+
     /** @private {?number} */
     this.audioPid_ = null;
 
@@ -55,6 +61,7 @@ shaka.util.TsParser = class {
    * @return {!shaka.util.TsParser}
    */
   parse(data) {
+    const timescale = shaka.util.TsParser.Timescale_;
     const packetLength = shaka.util.TsParser.PacketLength_;
 
     // A TS fragment should contain at least 3 TS packets, a PAT, a PMT, and
@@ -135,12 +142,28 @@ shaka.util.TsParser = class {
             this.pmtParsed_ = true;
             break;
           }
-          case this.videoPid_:
-            this.videoData_.push(data.subarray(offset, start + packetLength));
+          case this.videoPid_: {
+            const videoData = data.subarray(offset, start + packetLength);
+            if (this.videoStartTime_ == null) {
+              const pes = this.parsePES(videoData);
+              if (pes && pes.pts != null) {
+                this.videoStartTime_ = pes.pts / timescale;
+              }
+            }
+            this.videoData_.push(videoData);
             break;
-          case this.audioPid_:
-            this.audioData_.push(data.subarray(offset, start + packetLength));
+          }
+          case this.audioPid_: {
+            const audioData = data.subarray(offset, start + packetLength);
+            if (this.audioStartTime_ == null) {
+              const pes = this.parsePES(audioData);
+              if (pes && pes.pts != null) {
+                this.audioStartTime_ = pes.pts / timescale;
+              }
+            }
+            this.audioData_.push(audioData);
             break;
+          }
           case this.id3Pid_:
             this.id3Data_.push(data.subarray(offset, start + packetLength));
             break;
@@ -180,8 +203,8 @@ shaka.util.TsParser = class {
       audio: -1,
       video: -1,
       id3: -1,
-      audioCodec: 'aac',
-      videoCodec: 'avc',
+      audioCodec: '',
+      videoCodec: '',
     };
     const sectionLength = ((data[offset + 1] & 0x0f) << 8) | data[offset + 2];
     const tableEnd = offset + 3 + sectionLength - 4;
@@ -201,6 +224,7 @@ shaka.util.TsParser = class {
         case 0x0f:
           if (result.audio === -1) {
             result.audio = pid;
+            result.audioCodec = 'aac';
           }
           break;
         // Packetized metadata (ID3)
@@ -216,6 +240,7 @@ shaka.util.TsParser = class {
         case 0x1b:
           if (result.video === -1) {
             result.video = pid;
+            result.videoCodec = 'avc';
           }
           break;
         // ISO/IEC 11172-3 (MPEG-1 audio)
@@ -332,6 +357,30 @@ shaka.util.TsParser = class {
     return metadata;
   }
 
+  /**
+   * Return the start time for the audio and video
+   *
+   * @return {{audio: ?number, video: ?number}}
+   */
+  getStartTime() {
+    return {
+      audio: this.audioStartTime_,
+      video: this.videoStartTime_,
+    };
+  }
+
+  /**
+   * Return the audio and video codecs
+   *
+   * @return {{audio: ?string, video: ?string}}
+   */
+  getCodecs() {
+    return {
+      audio: this.audioCodec_,
+      video: this.videoCodec_,
+    };
+  }
+
   /**
    * Check if the passed data corresponds to an MPEG2-TS
    *
@@ -385,6 +434,13 @@ shaka.util.TsParser = class {
 shaka.util.TsParser.PacketLength_ = 188;
 
 
+/**
+ * @const {number}
+ * @private
+ */
+shaka.util.TsParser.Timescale_ = 90000;
+
+
 /**
  * @typedef {{
  *   audio: number,

diff --git a/test/util/ts_parser_unit.js b/test/util/ts_parser_unit.js
@@ -48,4 +48,26 @@ describe('TsParser', () => {
     expect(metadata).toBeTruthy();
     expect(metadata.length).toBe(2);
   });
+
+  it('get the start time from a TS segment', async () => {
+    const responses = await Promise.all([
+      Util.fetch('/base/test/test/assets/id3-metadata.ts'),
+    ]);
+    const tsSegment = BufferUtils.toUint8(responses[0]);
+    const starttime = new shaka.util.TsParser().parse(tsSegment)
+        .getStartTime();
+    expect(starttime.audio).toBeCloseTo(90019.586, 3);
+    expect(starttime.video).toBe(null);
+  });
+
+  it('get the codecs from a TS segment', async () => {
+    const responses = await Promise.all([
+      Util.fetch('/base/test/test/assets/id3-metadata.ts'),
+    ]);
+    const tsSegment = BufferUtils.toUint8(responses[0]);
+    const codecs = new shaka.util.TsParser().parse(tsSegment)
+        .getCodecs();
+    expect(codecs.audio).toBe('aac');
+    expect(codecs.video).toBe('');
+  });
 });