MP4 files are not playing properly from USB drives. The exact same file would play much better directly from the SD drive. This issue is very clear for HD MP4 which are 720p or 1080p. I get a green screen, ghost artifacts, sync issues, longer loading time etc. Youtube plugin videos have similar issues as well.
I read the forum and others had similar issues with playing MP4 files from USB drive. For some people it plays audio only etc. Tweaking the "hardware acceleration" and unchecking omxplayer acceleration fixed some issues, but not all. Some people had permissions issue for MP4 files as well which were fixed by using chmod.
BTW, I am using Raspberry Pi Zero with Raspbian Jessie Lite for this experiment and downloaded the latest Kodi Jarvis V16 which came from the pipplware.pplware.pt repository. Jessie LITE does not auto-mount USB or anything.
V16 from pipplware is much better than Kodi V15 which can be obtained directly from doing a regular apt-get from Jessie LITE without adding the pipplware.pplware.pt repository. V16 from pipplware.pplware.pt repository plays MP4 better, but, not as good as the standalone Kodi/Libreelec release specially made for Rpi0 with minimal OS.
So, the Jessie LITE with KODI Jarvis V16 obtained by doing a "apt-get" from pipplware.pplware.pt is better than V15 but not as good as the latest KODI standalone for RPi0.
Now back to the original issue:
Since the exact same file plays better from the SD card than the USB drive, is it a USB card vs. SD card data I/O "speed" issue or am I mounting the USB drive wrong? Have you seen this issue? Any fix?
I added the following to \etc\fstab and I did not use UUID because I use many random USB drives and hubs where UUID changes.
/dev/sda1 /mnt/usb1 vfat nofail,auto,noatime,rw,user 0 0
/dev/sda2 /mnt/usb2 vfat nofail,auto,noatime,rw,user 0 0
I also did the following:
sudo chown -R pi:pi /mnt/usb1 (repeated this for both /mnt/usb1 and /mnt/usb2)
sudo chmod -R 777 /mnt/usb1 (repeated for both usb1 and usb2)
sudo setfacl -Rdm g:pi:rwx /mnt/usb1 (repeated for both usb1 and usb2)
sudo setfacl -Rm g:pi:rwx /mnt/usb1 (repeated for both usb1 and usb2)
AVI plays OK. MKV is OK most of the time depends on CODEC used.