Bug 513531

Summary:	No tags for mp4 files larger than 4 GB
Product:	[Applications] kid3	Reporter:	Adrian Schweri <adrian.schweri>
Component:	general	Assignee:	Urs Fleisch <ufleisch>
Status:	REPORTED ---
Severity:	normal
Priority:	NOR
Version First Reported In:	3.9.x
Target Milestone:	---
Platform:	Microsoft Windows
OS:	Microsoft Windows
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Adrian Schweri 2025-12-18 09:15:54 UTC

SUMMARY
When using the Windows binaries (64-bit) kid3-3.9.7-win32-x64.zip, downloaded from https://kid3.kde.org/#download, under Microsoft Windows 11, no tags are displayed or editable for MP4 files larger than 4 GB. "No Tag" is displayed next to the MP4 file. The metadata plugins OggFlacMetadata and TaglibMetadata are enabled in the settings, the metadata plugins Id3libMetadata and Mp4v2Metadata are disabled. The bug occurs with both MP4 files on the local disk and on network shares.

SOFTWARE/OS VERSIONS
Windows: 11 Pro with latest updates

Comment 1 Urs Fleisch 2026-01-04 19:04:30 UTC

Thanks for the report. I generated a 4.9 GB file using

ffmpeg -f lavfi -i "color=c=black:size=1920x1080:rate=30:duration=489352" -f lavfi -i "sine=frequency=440:duration=489352" -c:v libx264 -preset ultrafast -c:a aac -y huge.mp4

and I was able to edit tags on Windows 10 with the TaglibMetadata plugin. When the file has to be enlarged, writing the tags can take quite some time and you will see "not responding" in the window title bar. With the Mp4v2Metadata plugin, it took so long that I lost patience and terminated the program. A temporary file was left, probably libmp4v2 was writing changes to that file but this process seems to be very slow.

By the way: Generating such a large file with ffmpeg took a lot of time and a lot of attempts because files having only audio could not be made larger than 4GB. Apparently, MP4 is not the best format for such large files.

Comment 2 Urs Fleisch 2026-01-11 20:17:08 UTC

I have found the issue, it is in TagLib. I have fixed it (https://github.com/taglib/taglib/pull/1296) and provided a version git20260111 in https://sourceforge.net/projects/kid3/files/kid3/development/, please test it.