TeamNewPipe/NewPipe

[YouTube] Out of sync audio and video in download (muxing issue)

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#12640 opened on Sep 17, 2025

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YouTubebugdownloaderhelp wanted

Description

Checklist

  • I am able to reproduce the bug with the latest version given here: CLICK THIS LINK.
  • I made sure that there are no existing issues - open or closed - which I could contribute my information to.
  • I have read the FAQ and my problem isn't listed.
  • I have taken the time to fill in all the required details. I understand that the bug report will be dismissed otherwise.
  • This issue contains only one bug.
  • I have read and understood the contribution guidelines.

Affected version

0.28.0

Steps to reproduce the bug

Download https://m.youtube.com/watch?v=sRTPiFzXxYQ in either 480p or 720p. You will see that the resulting video file has out of sync video (i.e. the video lags behind the audio). This is most likely a downlaoder muxing issue, related to #12443.

It would be good if someone who has some experience with the MP4 format (standard ISO/IEC 14496-12) could work on this.

Contributor guide

Tech stack
javaandroid
Domain
mobile
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
MP4/ISO 14496-12 knowledgeJavaAndroidMedia muxing
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25
Research direction
Investigate the downloader muxing component in the NewPipe codebase, likely in the 'downloader' or 'extractor' modules. Examine the related issue #12443 for context. Focus on the MP4 muxing process to identify why audio and video streams become out of sync. Consider testing with the provided YouTube video at 480p or 720p.