feat: Add AAC silent frame getter (#5557)

This is necessary for enable the muxed TS transmuxer in the future.
shaka-project · Aug 30, 2023 · 933f039 · 933f039
1 parent 123183d
commit 933f039
Showing 1 changed file with 78 additions and 0 deletions.
diff --git a/lib/transmuxer/adts.js b/lib/transmuxer/adts.js
@@ -146,6 +146,84 @@ shaka.transmuxer.ADTS = class {
   static getFrameDuration(samplerate) {
     return (shaka.transmuxer.ADTS.AAC_SAMPLES_PER_FRAME * 90000) / samplerate;
   }
+
+  /**
+   * @param {string} codec
+   * @param {number} channelCount
+   * @return {?Uint8Array}
+   */
+  static getSilentFrame(codec, channelCount) {
+    switch (codec) {
+      case 'mp4a.40.2':
+        if (channelCount === 1) {
+          return new Uint8Array([0x00, 0xc8, 0x00, 0x80, 0x23, 0x80]);
+        } else if (channelCount === 2) {
+          return new Uint8Array([
+            0x21, 0x00, 0x49, 0x90, 0x02, 0x19, 0x00, 0x23, 0x80,
+          ]);
+        } else if (channelCount === 3) {
+          return new Uint8Array([
+            0x00, 0xc8, 0x00, 0x80, 0x20, 0x84, 0x01, 0x26, 0x40, 0x08, 0x64,
+            0x00, 0x8e,
+          ]);
+        } else if (channelCount === 4) {
+          return new Uint8Array([
+            0x00, 0xc8, 0x00, 0x80, 0x20, 0x84, 0x01, 0x26, 0x40, 0x08, 0x64,
+            0x00, 0x80, 0x2c, 0x80, 0x08, 0x02, 0x38,
+          ]);
+        } else if (channelCount === 5) {
+          return new Uint8Array([
+            0x00, 0xc8, 0x00, 0x80, 0x20, 0x84, 0x01, 0x26, 0x40, 0x08, 0x64,
+            0x00, 0x82, 0x30, 0x04, 0x99, 0x00, 0x21, 0x90, 0x02, 0x38,
+          ]);
+        } else if (channelCount === 6) {
+          return new Uint8Array([
+            0x00, 0xc8, 0x00, 0x80, 0x20, 0x84, 0x01, 0x26, 0x40, 0x08, 0x64,
+            0x00, 0x82, 0x30, 0x04, 0x99, 0x00, 0x21, 0x90, 0x02, 0x00, 0xb2,
+            0x00, 0x20, 0x08, 0xe0,
+          ]);
+        }
+        break;
+      // handle HE-AAC below (mp4a.40.5 / mp4a.40.29)
+      default:
+        if (channelCount === 1) {
+          // eslint-disable-next-line max-len
+          // ffmpeg -y -f lavfi -i "aevalsrc=0:d=0.05" -c:a libfdk_aac -profile:a aac_he -b:a 4k output.aac && hexdump -v -e '16/1 "0x%x," "\n"' -v output.aac
+          return new Uint8Array([
+            0x1, 0x40, 0x22, 0x80, 0xa3, 0x4e, 0xe6, 0x80, 0xba, 0x8, 0x0, 0x0,
+            0x0, 0x1c, 0x6, 0xf1, 0xc1, 0xa, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5e,
+          ]);
+        } else if (channelCount === 2) {
+          // eslint-disable-next-line max-len
+          // ffmpeg -y -f lavfi -i "aevalsrc=0|0:d=0.05" -c:a libfdk_aac -profile:a aac_he_v2 -b:a 4k output.aac && hexdump -v -e '16/1 "0x%x," "\n"' -v output.aac
+          return new Uint8Array([
+            0x1, 0x40, 0x22, 0x80, 0xa3, 0x5e, 0xe6, 0x80, 0xba, 0x8, 0x0, 0x0,
+            0x0, 0x0, 0x95, 0x0, 0x6, 0xf1, 0xa1, 0xa, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5e,
+          ]);
+        } else if (channelCount === 3) {
+          // eslint-disable-next-line max-len
+          // ffmpeg -y -f lavfi -i "aevalsrc=0|0|0:d=0.05" -c:a libfdk_aac -profile:a aac_he_v2 -b:a 4k output.aac && hexdump -v -e '16/1 "0x%x," "\n"' -v output.aac
+          return new Uint8Array([
+            0x1, 0x40, 0x22, 0x80, 0xa3, 0x5e, 0xe6, 0x80, 0xba, 0x8, 0x0, 0x0,
+            0x0, 0x0, 0x95, 0x0, 0x6, 0xf1, 0xa1, 0xa, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a, 0x5a,
+            0x5a, 0x5e,
+          ]);
+        }
+        break;
+    }
+    return null;
+  }
 };
 
 /**