Video files always getting damaged after burning subtitles with Avidemux

[Rain-Maker]

Hello everyone,

I don't have much experience editing videos, I only burn subtitles, cut, and append sometimes. Now, when I get videos of very high quality and burn the subtitles, the resulting file sometimes plays kind of pixelated; the video also lags suddenly. I've thought it's a problem with my computer, but I sent one of the files to someone else to download it and the same happens. It's important to note that this doesn't happen every time I play the videos, just sometimes.

The details of one of these videos are:

.mp4
Width: 1080
Height: 1920
Data rate: 15810 kbps
Total bitrate: 15908 kbps
Frame rate: 60 frames/second


Audio:

Bit rate: 97 kbps
Channels: 1
Audio sample rate: 44 kHz

With Avidemux, I'm selecting Mpeg4 AVC (x264) for the output, rate control of 20 (happens with any setting for this), the audio output is just a copy.

I'm using Avidemux 2.7.5, and this happens when I play the video with WMP and VLC. Oddly, the parts that get pixelated are usually the same, but only for a specific player. I mean, the video gets pixelated in the same parts when I play it in VLC, but in different parts when I play it in WMP.

Another thing is that I've sent these videos to the owner, who uses Mac, and they say the video has no audio, which has in my PC and others I've played it on. They tried to upload it to some social media (not sure which), but got an error message saying the file was corrupted.

I'm a newbie with this.

I would appreciate your help.

[davexnet]

Can't you use soft subs instead? Then you wouldn't have to touch the video

[Rain-Maker]

Unfortunately, the exact requirement I'm getting is to burn them.

[davexnet]

What format are the subs? Secondly, what happens if you just re-encode the video without adding the subs - is it clean?

[Rain-Maker]

Well, I'll need to try that, haven't done it.

The subs are .ass. I need the formatting capability and positioning.

I just realized the video plays well originally, but when I add the subtitle file in VLC—just to display them—the same thing happens with the video. This makes me suspect that they're what's causing the problem. Let me run the test in a moment. The encoding occupies too many resources.