Troubleshooting

.kara.json files

Tools

.kara.json files must all be created and filled automatically by this form in the system panel.

Karaoke Mugen data generation

In the case you modify media files or lyrics, you can update .kara.json files in several ways.

  • From a karaoke page in the system panel : drag and drop your new media or lyrics file in the form and save changes so karaoke Mugen will create a new .kara.json and replace the old one.
  • When Karaoke Mugen starts with the --validate option, the software will check if your files were changed. If they have changed, they will be updated and karaoke Mugen will exit.
  • From the system panel : in the Database menu click on Validate

Common issues

Video file can not be found despite being present

Verify on the FTP that the file is named exactly like in the .kara.json. Beware of case! Since Windows is case-insensitive, it won't have any trouble, but for Linux where the lab is hosted, it will cause issues. Look carefully.

Another possibily is an invisible parasite character, a double space or something other from that. In doubt, copy-paste the file name from the .kara.json while renaming you media file

.ass files

Your subtitles are shifted/unsynced

Look up the time shifting section from the advanced guide

Medias

Tools

To encode videos, an array of tools exists.

  • Handbrake is the easiest to use, with a relatively correct user interface that is readable and somewhat good default options.
  • MediaCoder is a bit more shaky but is full of extra stuff: like the ability to keep some media tracks and re-encode other ones. Beware, it is a freemium: some options are only usable with the software's full version.
  • MeGUI is a lot more harder to use but opitimizes encoding.
  • FFMPEG can be used in command line, making it very powerful but hard to master.
  • ShotCut allows to cut videos at the exact frame you want and uses FFMPEG, which makes your exports lighter.

Common issues

False metadata

In rare cases the "duration" can be wrong compared to reality. If it happens, it's possible to get rid of the problem by recalibrating the video track and the incriminated audio in an MP4 container, using ffmpeg and the following command line (see the dedicated section) :

./ffmpeg -i video_source.mp4 -vcodec copy -acodec copy video_destination.mp4

"Crushed" lyrics on Karaoke Mugen

If you see that lyrics at the top of the screen seem to be crushed compared to other karaokes. It's because the video's ratio is incorrect. It can be fixed with FFMPEG. Come ask us on Discord.

Very big video files

Please use the tools and check rules on this page to produce light video files depending on their initial resolution. Sometimes re-encoding will be needed.

As a reminder, here are the expected video formats and the length/size ratio of videos:

  • Container: MP4
  • Video codec: h264 8bit
  • Audio codec: AAC

That table is indicative: for a given image resolution you should use the maximum Bitrate listed below to get an acceptable video size.

The karaoke base having a huge size already, it's important to take as little space as possible. Having a 130Mb file for 1 minute 30 of video is not acceptable.

Video Resolution (Y axis) Maximum Birate Appromative file size, for 1 min 30
4K 10000 kb/s 100Mb
1080p 8000 kb/s 80Mb
720p 4000 kb/s 40Mb
480p 3000 kb/s 30Mb
360p 2000 kb/s 20Mb