Solved Converting MKV to MP4 puts video/audio way out of sync.

JAM83 · Jan 3, 2025

So, i created a video and saved it as an MKV. . Well, it's 1.79GB. . I need that video to be around 300MB. So i tried Handbrake. . It has the video/audio way out of sync. Can anyone help me fix this?

Code:

Format :Matroska
Format version :Version 2
File size :1.79 GiB
Duration :53 min 1 s
Overall bit rate mode :Variable
Overall bit rate :5 703 kb/s
Frame rate :29.970 FPS

Video

ID :1
ID in the original source medium :224 (0xE0)
Format :MPEG Video
Format version :Version 2
Format profile :Main@Main
Format settings :CustomMatrix / BVOP
Format settings, BVOP :Yes
Format settings, Matrix :Custom
Format settings, GOP :Variable
Format settings, picture structure :Frame
Codec ID :V_MPEG2
Codec ID/Info :MPEG 1 or 2 Video
Duration :45 min 1 s
Bit rate mode :Variable
Bit rate :5 499 kb/s
Maximum bit rate :9 800 kb/s
Width :720 pixels
Height :480 pixels
Display aspect ratio :16:9
Frame rate mode :Constant
Frame rate :29.970 (30000/1001) FPS

Audio

ID :2
ID in the original source medium :189 (0xBD)128 (0x80)
Format :AC-3
Format/Info :Audio Coding 3
Commercial name :Dolby Digital
Codec ID :A_AC3
Duration :44 min 59 s
Bit rate mode :Constant
Bit rate :192 kb/s
Channel(s) :2 channels
Channel layout :L R
Sampling rate :48.0 kHz
Frame rate :31.250 FPS (1536 SPF)
Compression mode :Lossy
Delay relative to video :2 s 336 ms
Stream size :61.8 MiB (3%)
Title :Stereo

FreeBooter · Jan 3, 2025

Easy way to convert MKV to MP4 with ffmpeg

Easy way to convert MKV to MP4 with ffmpeg. GitHub Gist: instantly share code, notes, and snippets.

gist.github.com

Taliseian · Jan 3, 2025

I create videos from my Twitch VODS. I save them locally while filming Twitch in .MKV format and the program that I use to create them - OBS Studio - auto converts to .MP4. I then do some minor editing in DaVinci Resolve and upload to YouTube.

What program are you using to create your video? I wonder if there is an issue with the file that program creates.

JAM83 · Jan 3, 2025

FreeBooter said:
Easy way to convert MKV to MP4 with ffmpeg

Easy way to convert MKV to MP4 with ffmpeg. GitHub Gist: instantly share code, notes, and snippets.

gist.github.com

i have no idea how to use ffmpeg

FreeBooter · Jan 3, 2025

FFmpeg Tutorial 101 - FFmpeg MKV to MP4 Conversion

Do you want to convert FFmpeg MKV to MP4 easily? Come in and quickly learn about the parameters of FFmpeg command lines, which are greatly helpful to convert multimedia files with FFmpeg.

www.videoconverterfactory.com

abactuon · Jan 3, 2025

Anime Encoding Guide for x265 (HEVC) & AAC/OPUS (and Why to Never Use FLAC)

External Links Yuki Subs Guides has a master list of guides of all you need to know about anime encoding. Also, go visit my MPC-HC + MadVR, mpv, and SVP 4 setup guide! Table of Contents x265 Settin…

kokomins.wordpress.com

JAM83 · Jan 3, 2025

FreeBooter said:
FFmpeg Tutorial 101 - FFmpeg MKV to MP4 Conversion

Do you want to convert FFmpeg MKV to MP4 easily? Come in and quickly learn about the parameters of FFmpeg command lines, which are greatly helpful to convert multimedia files with FFmpeg.

www.videoconverterfactory.com

ffmpeg -i TBA04.mkv -codec copy TBA04.mp4

The command worked, but there is still a video/audio sync problem

idgat · Jan 3, 2025

Another vote for ffmpeg
Easily fix async video with ffmpeg and multiple other search results)

Or the more simplistic GUI version ffmpeg Batch

Alternatively, AVIDeMux (you can adjust the synch in the settings)

EDIT
I suspect the synch problems lies in the original file, even though it's not obvious in the original file

A crash course in video files ...
- a video file type (.mp4, .mkv, .avi, etc etc) is simply a "container" for an audio stream format (of which there are multiples) and a video stream format (of which there are multiple also)
- audio and video streams are not related to any particular file type extensions, and they can vary withing the same file type extension
- converting a video file from one type to another does not necessarily change the format of the video and/or audio stream within that file, and therein lies the possibility for your problems

To identify the video and audio stream formats in your file, use freeware program MediaInfo

JAM83 · Jan 3, 2025

idgat said:
Another vote for ffmpeg (or the more simplistic GUI version ffmpeg Batch)

Alternatively, AVIDeMux

already tried AVIDeMux and it didn't work either

idgat · Jan 3, 2025

JAM83 said:
already tried AVIDeMux and it didn't work either

see previous post updates

JAM83 · Jan 3, 2025

idgat said:
Another vote for ffmpeg
Easily fix async video with ffmpeg and multiple other search results)

Or the more simplistic GUI version ffmpeg Batch

Alternatively, AVIDeMux (you can adjust the synch in the settings)

EDIT
I suspect the synch problems lies in the original file, even though it's not obvious in the original file

A crash course in video files ...
- a video file type (.mp4, .mkv, .avi, etc etc) is simply a "container" for an audio stream format (of which there are multiples) and a video stream format (of which there are multiple also)
- audio and video streams are not related to any particular file type extensions, and they can vary withing the same file type extension
- converting a video file from one type to another does not necessarily change the format of the video and/or audio stream within that file, and therein lies the possibility for your problems

To identify the video and audio stream formats in your file, use freeware program MediaInfo

I done the MediaInfo thing. . I posted the information in my original post.

Dannydet · Jan 3, 2025

Have you tried VLC?
You should be able to convert mkv to mp4 without any issues

JAM83 · Jan 4, 2025

Dannydet said:
Have you tried VLC?
You should be able to convert mkv to mp4 without any issues

yep. . I've tried VLC, and a few other softwares. . I'm gonna completely redo the video and see if it'll work. . It might have been corrupted somehow. . I've done other videos the same way over the past 3 or 4 days, and not a problem with any of them, except this one.

Stigg · Jan 4, 2025

HandBrake is normally very reliable. I've been using it for years.
Maybe try converting it to MP4 first and see if the audio is still in sync.

JAM83 · Jan 4, 2025

I fixed it. . I trimmed 2 seconds off the front of the video and it fixed the issue. . .

TahitianVibes · Jan 4, 2025

you can see it in your mediainfo - there is :

Delay relative to video :2 s 336 ms
that's what caused the audio lag.

For a clean audio/video sync, try this next time:

Synchronize audio and video with FFmpeg - Geeky Hacker

You can use FFmpeg to synchronize audio and video by combining -itsoffset and -map parameters to respectively delay and copy input streams.

www.geekyhacker.com

hsehestedt · Jan 4, 2025

EDIT: Don't know why I missed this on my first reading, but I see that you have already resolved the issue. Sorry for missing that. You can ignore the below.

Two Items:

1) Ultimately, if you could post a sample video to OneDrive, Goole, etc. that would be helpful because I could try my ideas on your real-world video.

2) My methodology would be a bit different. An MKV is just a container - it may very likely have an MP4 file in there already. To reduce the file size that drastically (without changing the frame dimensions) might be difficult if you are simply going from MP4 to MP4. My suggestion would be to try converting to HEVC (H.265) using handbrake. HEVC is far superior in compression to MP4.

NOTE: If you have hardware decoding such as QuickSync in Intel CPUs, handbrake will give you an option to perform the HEVC encoding using that hardware or using a software encoder. The hardware encoder is WAY faster (I can't stress how huge the difference is), but it can sometimes be slightly less compatible. On rare occasions I find that I need to fall back to the software encoder.

PCUser · Jan 4, 2025

I use VLC (free) fast, efficient, easy, works great every time.

Launch VLC

In above menu items choose MEDIA - CONVERT/SAVE

Click + and select MP4 file for converting

Under PROFILE click the WRENCH icon and select MKV

Click the video codec tab above and select VIDEO and KEEP ORIGINAL TRACK

Next click the audio codec tab and select AUDIO and KEEP ORIGINAL AUDIO TRACK

click SAVE and START

Solved Converting MKV to MP4 puts video/audio way out of sync.

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