fix: make a fake GOP when video dont have B/P frame (#85)

zhihu · Apr 22, 2019 · 116c19a · 116c19a
1 parent bcd054a
commit 116c19a
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Showing 3 changed files with 45 additions and 2 deletions.
diff --git a/packages/griffith-mp4/src/mp4/utils/__tests__/getSamplesInterval.spec.js b/packages/griffith-mp4/src/mp4/utils/__tests__/getSamplesInterval.spec.js
@@ -1,4 +1,5 @@
 import {
+  getIntervalArray,
   getVideoSamplesInterval,
   getAudioSamplesInterval,
   getNextVideoSamplesInterval,
@@ -42,4 +43,29 @@ describe('getSamplesInterval', () => {
       timeInterVal: [56056, 86086],
     })
   })
+
+  it('should get the sample interval array when video has B/P frame', () => {
+    const mockStssBox = {
+      samples: [
+        {
+          sampleNumber: 1,
+        },
+        {
+          sampleNumber: 251,
+        },
+        {
+          sampleNumber: 501,
+        },
+      ],
+    }
+    expect(getIntervalArray(mockStssBox)).toEqual([0, 250, 500])
+  })
+
+  it('should get the sample interval array when video has B/P frame', () => {
+    const mockStszBox = {
+      samples: [],
+    }
+    mockStszBox.samples.length = 21
+    expect(getIntervalArray(undefined, mockStszBox)).toEqual([0, 5, 10, 15, 20])
+  })
 })
diff --git a/packages/griffith-mp4/src/mp4/utils/getSamplesInterval.js b/packages/griffith-mp4/src/mp4/utils/getSamplesInterval.js
@@ -7,7 +7,7 @@ export function getVideoSamplesInterval(mp4BoxTree, time = 0) {
   const stszBox = findBox(mp4BoxTree, 'videoStsz')
   const duration = getDuration(sttsBox, stszBox.samples.length)
 
-  const intervalArray = stssBox.samples.map(sample => sample.sampleNumber - 1)
+  const intervalArray = getIntervalArray(stssBox, stszBox)
   const timeInterval = intervalArray.map(interval =>
     getDuration(sttsBox, interval)
   )
@@ -87,12 +87,13 @@ export function getAudioSamplesInterval(mp4BoxTree, videoInterval) {
 
 export function getNextVideoSamplesInterval(mp4BoxTree, sample) {
   const stssBox = cloneDeep(findBox(mp4BoxTree, 'videoStss'))
-  const intervalArray = stssBox.samples.map(sample => sample.sampleNumber - 1)
   const sttsBox = cloneDeep(findBox(mp4BoxTree, 'videoStts'))
   const stszBox = findBox(mp4BoxTree, 'videoStsz')
   const sampleCount = stszBox.samples.length
   const duration = getDuration(sttsBox, sampleCount)
 
+  const intervalArray = getIntervalArray(stssBox, stszBox)
+
   const timeInterval = intervalArray.map(interval =>
     getDuration(sttsBox, interval)
   )
@@ -114,3 +115,17 @@ export function getNextVideoSamplesInterval(mp4BoxTree, sample) {
   }
   return result
 }
+
+export function getIntervalArray(stssBox, stszBox) {
+  let intervalArray = []
+  if (stssBox) {
+    intervalArray = stssBox.samples.map(sample => sample.sampleNumber - 1)
+  } else {
+    // make a fake GOP when video dont have B/P frame
+    for (let i = 0; i <= Math.floor(stszBox.samples.length / 5); i++) {
+      intervalArray.push(i * 5)
+    }
+  }
+
+  return intervalArray
+}
diff --git a/packages/griffith-mp4/src/mp4/utils/index.js b/packages/griffith-mp4/src/mp4/utils/index.js
@@ -5,6 +5,7 @@ import getFragmentPosition from './getFragmentPosition'
 import getBufferStart from './getBufferStart'
 import {getVideoSamples, getAudioSamples} from './getSamples'
 import {
+  getIntervalArray,
   getAudioSamplesInterval,
   getVideoSamplesInterval,
   getNextVideoSamplesInterval,
@@ -15,6 +16,7 @@ import getDuration from './getDuration'
 export {
   findBox,
   getDuration,
+  getIntervalArray,
   getSamplesOffset,
   getPerChunkArray,
   getFragmentPosition,