Believe me I worked hard to find this one!
I sucessfully include the replaygain field in the main window.
I use WinAmp to calculate the replay gain and with MP3Tag I can edit the value easily if I need.
Everything is wonderfull but and there a but..
MP4 video files.
I got around 200 video file in MP4 format (H.264 and AAC audio stream).
I already tag them with with MP3Tag, included a covert art and everything was fine.
After that I use Winamp to ReplayGain those MP4.
Result, about 10% of the file lost their tag in MP3Tag.
MP3Tag said there is no Tag.
In Winamp the tag are still there.
If I use Tag&Rename the tag are still there.
In fact those tag are still there but MP3Tag doesn't see them anymore.
No problem with my MP3 collection. ReplayGain on a thousand of file without loosing any tags in MP3Tag.
The problem occur in MP4 video files.
I opened the problematic files with a hex editor and I see nothing but chinese from my point of vue.
I can't see any corellation between those video file. In naming or tag format. I made the ReplayGain twice with a backup... and the problem occur with the same files.
Those files are about 200Megs in size, so sending a copy is not an option.
So I delete the tag from the original problematic file and create a new tag with other value. Now I can ReplayGain them and I got no problem.
Conclusion; there is something with the data in the tag that corrupt the files. What exactly?
The genre field.
If I included a genre that is in the preset list (the one used in MP3 v1 tag format genre list).
The one's problematic for me;
Any other genre not in the list doesn't create this problem.
If you can fix it in a next build that would be great.
Or maybe it's a Winamp problem but remember Tag&Rename can see the tag all the time.
I can't tell your where exactly the problem is.
Thanks for reading.