fix: 🐛 AnnexB Nalu with trailing zeros

bytedance · Dec 23, 2024 · 17051a3 · 17051a3
1 parent dc22b0b
commit 17051a3
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Showing 2 changed files with 34 additions and 5 deletions.
diff --git a/packages/xgplayer-transmuxer/__tests__/codec/nalu.spec.js b/packages/xgplayer-transmuxer/__tests__/codec/nalu.spec.js
@@ -2,30 +2,40 @@ import { NALu } from '../../src/codec'
 
 describe('NALu', () => {
 
-  test('parseAnnexB', () => {
+  test('parseAnnexB with multiple start codes & mixed start codes', () => {
     const uint0 = [9, 240]
     const uint1 = [103, 100, 0, 31, 172, 217, 64, 212, 61, 176, 17, 0, 0, 3, 0, 1, 0, 0, 3, 0, 120, 15, 24, 49, 150]
     const uint2 = [104, 235, 226, 75, 34, 192]
     const uint3 = [226, 249, 198, 12, 0, 0, 0, 70, 83, 84, 83, 29, 1, 168, 170, 147, 1, 0, 0, 18] // 00 00 00 + not 1
+    const uint4 = [226, 9, 240] // trailing zeros
     const data = new Uint8Array([
       0, 0, 0, 1,
       ...uint0,
-      0, 0, 0, 1,
+      0, 0, 1,
       ...uint1,
       0, 0, 0, 1,
       ...uint2,
-      0, 0, 1,
+      0, 0, 0, 1,
       ...uint3,
-      0, 0, 1
+      0, 0, 1,
+      ...uint4,
+      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 // trailing zeros
     ])
 
     const result = NALu.parseAnnexB(data)
 
-    expect(result.length).toBe(4)
+    expect(result.length).toBe(5)
     expect(result[0]).toEqual(new Uint8Array(uint0))
     expect(result[1]).toEqual(new Uint8Array(uint1))
     expect(result[2]).toEqual(new Uint8Array(uint2))
     expect(result[3]).toEqual(new Uint8Array(uint3))
+    expect(result[4]).toEqual(new Uint8Array(uint4))
+  })
+
+  test('parseAnnexB with no NAL units', () => {
+    const data = new Uint8Array([0, 0, 0, 1])
+    const result = NALu.parseAnnexB(data)
+    expect(result.length).toBe(0)
   })
 
   test('parseAvcC', () => {

diff --git a/packages/xgplayer-transmuxer/src/codec/nalu.js b/packages/xgplayer-transmuxer/src/codec/nalu.js
@@ -6,6 +6,25 @@ export class NALu {
    * @returns {Uint8Array[]}
    */
   static parseAnnexB (data) {
+    let j = data.byteLength - 1
+    let dropZerosLength = 0
+    // Collect tailing zeros.
+    // end with 0x000000 and more...
+    do {
+      if (data[j] === 0x00) {
+        dropZerosLength++
+      } else {
+        break
+      }
+
+      j--
+    } while (j > 0)
+
+    if (dropZerosLength >= 3) {
+      // drop tailing zeros.
+      data = data.subarray(0, j + 1)
+    }
+
     const len = data.length
     let start = 2
     let end = 0