Encode to MP4
The best way to encode your video files is to export your work into a production codec (ProRes, DNxHD or uncompressed, for example). Then, use the open source tool Handbrake to convert it into an mp4. Make sure to use h264 as codec, otherwise the video will be software-decoded and might stutter. For 4k on Raspi4, it has to be h265 encoded.
For synchronized playback on MP4Museum-Sync, it has to be h264, best with constant bitrate for audio. There is no support for h265. Also, do not use variable framerates. The clips should be the same length on all players, and not to short, as it takes a few tries at first for the slaves to sync.
If you want seamless loops, make sure to name the file “loop.mp4”, which will enable a special loop mode, so that the playing software runs continously. Depending on your content, if you experience lag around the loop, try different bitrates or keyframe modes in Handbrake.
The startup video (“MP4Museum” etc.) should come on after booting. Also, depending on your setup, you might hear the startup sound of an old projector.
You can make changes to the config.txt on the boot drive for setting options or to force certain video modes. This can be useful when the display or projector is incorrectly, or not at all detected.
The boot partition should show up on your computer after writing the image, or when you plug in the card again. Open the file config.txt with a standard text editor.
Setting the Video Mode manually via config.txt might help when the mode cannot be set via discovery on boot, or the setup uses the wrong mode by default. It can also help when you turn on player and projector/monitor at the same time, and there is no picture as the output is not ready to recieve on boot.
For example, add
hdmi_group=1 hdmi_mode=16 hdmi_force_mode=1 hdmi_force_hotplug=1
to the config.txt which will force 1920×1080 at 60hz. Or
will give you 1920×1200 at 60hz.
These setting will prevent the Pi from figuring out what resolution to use, but use the given video mode. To find out what modes are possible using a connected output device, login via ssh and see info via “tvservice -s”.
Find complete information on video modes and options on raspberry.org.
Overscan / Clipping / Cropping
To adjust the image by moving its borders inwards, replace “disable_overscan=1” with
disable_overscan=0 overscan_left=1 overscan_right=1 overscan_top=1 overscan_bottom=1
Increase the Values on each side until you can see your media properly.
Using Composite Video Output
If you need analog video output for that old CRT Monitor, sure thing! The really old Raspberries have a RCA jack for output, for some like the Zero you need to solder to make the connection. In any case, you will need to make changes to config.txt to enable TV out, and set the correct format.
Find out more here: Raspberry Pi Documentation on SDTV