Bug: Exit code 1 with no error trace on MKV containing embedded cover art

[bartoszsporek]

Running jellycc check on an MKV file with an embedded cover art stream (PNG, attached_pic) causes the CLI to exit with code 1 and no error message or stack trace.

The README mentions "Embedded Junk Detection" as a feature, so this case should either be handled gracefully (auto-stripped) or produce a meaningful error.

Steps to Reproduce

1. Obtain an MKV file with an embedded PNG cover art stream (DISPOSITION:attached_pic=1)
2. Run jellycc check path/to/file.mkv
3. CLI exits immediately with code 1, no output

Workaround

Stripping the cover art with FFmpeg before running jellycc resolves the issue:

ffmpeg -i input.mkv -map 0 -map -0:8 -c copy output_nocover.mkv

Environment

• OS: Ubuntu (Linux)
• FFmpeg version: 6.1.1-3ubuntu5
• jellycc-cli version: latest (v0.3.0)

Offending stream

index=8
codec_name=png
codec_type=video
width=900
height=900
DISPOSITION:attached_pic=1
TAG:filename=cover.png
TAG:mimetype=image/png

Expected Behavior

jellycc should detect the embedded cover art, handle or strip it automatically, and continue normally — or at minimum output a descriptive error instead of a silent exit code 1.

[parkejunior]

Hello friend!

First, thank you for the organized issue, I appreciate it. I will use it as a template for future issues.

Regarding the problem, the CLI should have warned about the attachment like this:

I had a movie here with a cover, but it was in mjpg, so it warned it for me. I attached a cover.png file in another file and it also warned it:

I checked the code, and it finds for streams in bmp, png, and mjpg, but perhaps there's a particularity with your file. Could you give me the output of ffprobe for your file?