fix: detect access units in YouTube HLS AVC1 path

[Priveetee]

Summary

This PR fixes severe AVC1/H264 stutter on affected Pixel devices by changing YouTube HLS extractor configuration in one localized code path.

The patch is small because the root cause is localized: enabling access-unit detection in the YouTube HLS TS parsing path resolves the reproduced stutter behavior.

Related reports

• [Bug] Pixel 8 AVC1/H264 1080p60 stutter — clean repro + artifacts #23
• [Bug] Buffering Issues with AVC1 Videos PipePipe#2074
• [Bug] (AVC1) Video playback stutters/lag PipePipe#2045
• Videoplayback stutters on some Videos TeamNewPipe/NewPipe#13062 (comment)

Problem

On affected Pixel devices, YouTube AVC1/H264 playback can stutter heavily (audio remains in sync), with bursty dropped-frame patterns.
Observed decoder path on repro device: c2.exynos.h264.decoder.

Investigation highlights

• Reproduced outside PipePipe UI (Media3 demo), so this is not a PipePipe UI-thread issue.
• Cross-device comparison showed decoder/device specificity:
  • Pixel 8: reproducible drops
  • Z Fold 5 (c2.qti.avc.decoder): same stream family smooth
• Bitrate-only hypothesis was ruled out (re-encodes at different bitrates were stable).
• A/B testing pointed to HLS AVC1 access-unit parsing/feeding behavior.

Code change

File:

• app/src/main/java/org/schabi/newpipe/player/helper/PlayerDataSource.java

Change in getYoutubeHlsMediaSourceFactory():

• enable DefaultTsPayloadReaderFactory.FLAG_DETECT_ACCESS_UNITS
• use DefaultHlsExtractorFactory(payloadReaderFlags, true)

This adjusts how H264 TS payload is split into access units before decoder input.

Validation (A/B, same repro setup)

• detect-AU ON: 0 / 0 / 0 / 0 / 0 / 0 / 0 dropped frames (7 runs)
• detect-AU OFF (control): 13 / 312 / 573 dropped frames (3 runs)

Also validated in continuous real-device usage after patch: playback remained smooth.

Scope

• YouTube HLS extractor path only
• No codec forcing
• No quality forcing
• No UI behavior changes
• DASH/progressive paths unchanged

Build verification

• Local build passes with this change: :app:assembleDebug

[InfinityLoop1308]

Thanks a lot for the fix! I saw all the comparative testing you did. Very solid work.
Merging now.