Audio artifacts (crackling) after MKV → MP4 remux/conversion in OBS Studio

Operating System Info

macOS 15

Other OS

No response

OBS Studio Version

32.0.4

OBS Studio Version (Other)

No response

OBS Studio Log URL

None

OBS Studio Crash Log URL

No response

Expected Behavior

When converting or remuxing a recorded .mkv file to .mp4 using OBS, the resulting MP4 file contains audible artifacts (crackling/popping sounds).

The original .mkv file has clean, correct audio with no issues.

Expected Behavior:
The .mp4 file should preserve the same clean audio quality as the original .mkv recording.

Workaround:
If the audio track is extracted and converted using FFmpeg, the issue does not occur. For example:

ffmpeg -i original_rec.mkv -q:a 0 -map 0:1 -ar 48000 -b:a 192k game.aac

The resulting .aac file has clean audio identical to the original recording.

Current Behavior

The .mp4 file introduces audio artifacts (crackling), even though the source .mkv audio is clean.

Steps to Reproduce

1. Record a video in OBS using .mkv format
2. Use OBS to remux or convert the file to .mp4
3. Play the resulting .mp4 file in Final Cut Pro
4. Notice audio artifacts (crackling/popping)

Anything else we should know?

No response

Start by reproducing the remux or conversion from MKV to MP4 on macOS 15 with OBS Studio 32.0.4, then compare the source and output audio. Review the OBS FFmpeg conversion path and use the provided FFmpeg extraction command as a clean-audio comparison. Done means the generated MP4 preserves the source audio without crackling or popping.