Fix seeking into and over multiple EXT-X-GAP segments

Fixes #6814
video-dev · Feb 1, 2025 · a9863a5 · a9863a5
1 parent 305a3a7
commit a9863a5
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Showing 6 changed files with 26 additions and 13 deletions.
diff --git a/api-extractor/report/hls.js.api.md b/api-extractor/report/hls.js.api.md
@@ -1866,7 +1866,7 @@ export class FragmentTracker implements ComponentAPI {
     getBufferedFrag(position: number, levelType: PlaylistLevelType): MediaFragment | null;
     // (undocumented)
     getFragAtPos(position: number, levelType: PlaylistLevelType, buffered?: boolean): MediaFragment | null;
-    getPartialFragment(time: number): Fragment | null;
+    getPartialFragment(time: number): MediaFragment | null;
     // (undocumented)
     getState(fragment: Fragment): FragmentState;
     // (undocumented)

diff --git a/src/controller/base-stream-controller.ts b/src/controller/base-stream-controller.ts
@@ -1215,11 +1215,11 @@ export default class BaseStreamController
         bufferedFragAtPos &&
         (bufferInfo.nextStart <= bufferedFragAtPos.end || bufferedFragAtPos.gap)
       ) {
-        return BufferHelper.bufferInfo(
-          bufferable,
-          pos,
-          Math.max(bufferInfo.nextStart, maxBufferHole),
+        const gapDuration = Math.max(
+          Math.min(bufferInfo.nextStart, bufferedFragAtPos.end) - pos,
+          maxBufferHole,
         );
+        return BufferHelper.bufferInfo(bufferable, pos, gapDuration);
       }
     }
     return bufferInfo;

diff --git a/src/controller/fragment-tracker.ts b/src/controller/fragment-tracker.ts
@@ -321,7 +321,7 @@ export class FragmentTracker implements ComponentAPI {
   /**
    * Gets the partial fragment for a certain time
    */
-  public getPartialFragment(time: number): Fragment | null {
+  public getPartialFragment(time: number): MediaFragment | null {
     let bestFragment: Fragment | null = null;
     let timePadding: number;
     let startTime: number;

diff --git a/src/controller/gap-controller.ts b/src/controller/gap-controller.ts
@@ -12,7 +12,7 @@ import type { InFlightData } from './base-stream-controller';
 import type { InFlightFragments } from '../hls';
 import type Hls from '../hls';
 import type { FragmentTracker } from './fragment-tracker';
-import type { Fragment } from '../loader/fragment';
+import type { Fragment, MediaFragment } from '../loader/fragment';
 import type { SourceBufferName } from '../types/buffer';
 import type {
   BufferAppendedData,
@@ -503,7 +503,7 @@ export default class GapController extends TaskLoop {
    * @param partial - The partial fragment found at the current time (where playback is stalling).
    * @private
    */
-  private _trySkipBufferHole(partial: Fragment | null): number {
+  private _trySkipBufferHole(partial: MediaFragment | null): number {
     const { fragmentTracker, media } = this;
     const config = this.hls?.config;
     if (!media || !fragmentTracker || !config) {
@@ -515,7 +515,7 @@ export default class GapController extends TaskLoop {
     const bufferInfo = BufferHelper.bufferInfo(media, currentTime, 0);
     const startTime =
       currentTime < bufferInfo.start ? bufferInfo.start : bufferInfo.nextStart;
-    if (startTime) {
+    if (startTime && this.hls) {
       const bufferStarved = bufferInfo.len <= config.maxBufferHole;
       const waiting =
         bufferInfo.len > 0 && bufferInfo.len < 1 && media.readyState < 3;
@@ -541,6 +541,19 @@ export default class GapController extends TaskLoop {
                 PlaylistLevelType.MAIN,
               );
             if (startProvisioned) {
+              // Do not seek when switching variants
+              if (!this.hls.levels[this.hls.loadLevel]?.details) {
+                return 0;
+              }
+              // Do not seek when loading frags
+              const inFlightDependency = getInFlightDependency(
+                this.hls.inFlightFragments,
+                startTime,
+              );
+              if (inFlightDependency) {
+                return 0;
+              }
+              // Do not seek if we can't walk tracked fragments to end of gap
               let moreToLoad = false;
               let pos = startProvisioned.end;
               while (pos < startTime) {
@@ -567,7 +580,7 @@ export default class GapController extends TaskLoop {
         );
         this.moved = true;
         media.currentTime = targetTime;
-        if (!partial?.gap && this.hls) {
+        if (!partial?.gap) {
           const error = new Error(
             `fragment loaded with buffer holes, seeking from ${currentTime} to ${targetTime}`,
           );

diff --git a/src/controller/stream-controller.ts b/src/controller/stream-controller.ts
@@ -237,7 +237,7 @@ export default class StreamController
 
   protected onTickEnd() {
     super.onTickEnd();
-    if (this.media?.readyState) {
+    if (this.media?.readyState && this.media.seeking === false) {
       this.lastCurrentTime = this.media.currentTime;
     }
     this.checkFragmentChanged();

diff --git a/tests/unit/controller/gap-controller.ts b/tests/unit/controller/gap-controller.ts
@@ -16,7 +16,7 @@ import {
 import { MockMediaElement, MockMediaSource } from '../utils/mock-media';
 import type { HlsConfig } from '../../../src/config';
 import type StreamController from '../../../src/controller/stream-controller';
-import type { Fragment } from '../../../src/loader/fragment';
+import type { Fragment, MediaFragment } from '../../../src/loader/fragment';
 
 chai.use(sinonChai);
 const expect = chai.expect;
@@ -202,7 +202,7 @@ describe('GapController', function () {
       const bufferInfo = BufferHelper.bufferedInfo([], 0, 0);
       sandbox
         .stub(gapController.fragmentTracker, 'getPartialFragment')
-        .returns({} as unknown as Fragment);
+        .returns({} as unknown as MediaFragment);
       const skipHoleStub = sandbox.stub(gapController, '_trySkipBufferHole');
       gapController._tryFixBufferStall(bufferInfo, 100);
       expect(skipHoleStub).to.have.been.calledOnce;