MythTV moved to Pi4
The new-to-me (used off ebay) Raspi4 came in but I had to wait on the microHDMI to come in from Amazon. The 3A USB-C power supply is still floating out there somewhere, but I forgot I’d installed a 3.1A USB outlet nearby. I was hoping to move the sdcard from the pi2 straight over instead of having to do a fresh install.
getting it running
boot hangs
The pi4 seemed to bootloop while showing the splash screen, something I’d seen on the pi2 from time to time. Sometimes it would fix itself, sometimes not.
I pulled the card and SSD and fscked them from the laptop. Still no joy.
I couldn’t read what was scrolling on the bootscreen because the splash kept coming up. I finally figured out this was plymouth and figured out how to disable the splash screen. Turns out the hang was the fsck on the drives. I don’t know if plymouth was dorking up something, but after it was disabled the fsck were able to do their work without excessive delay and the system booted.
static DHCP lease
I configured the router to hand out the previously-allocated IP to the Pi4’s MAC, but it wasn’t taking no matter how many times I released/requested. Rebooted the router and the next time it took.
up and running
At this point the box was running and I could start poking around.
GPU RAM
I bumped the GPU allotment to 256MB, a number that googling suggested would be sufficient.
IO glitches
I was seeing weird hangs, CPU spikes, etc. I looked at vmstat and could see process blocked by I/0. It would hang, then blast a lot of disk activity, hang, etc. dmesg showed the SSD USB adapter resetting before each blast.
I’d plugged the SSD into one of the USB3 ports so I shut it down and moved it to a USB2 port; problem solved.
memory
Oh lordy, 8GB of RAM feels like a wide open meadow after the Pi2’s 1GB. There are multiple GB free even after GPU has stolen some and linux has taken what it wants for buffers/caches. No regrets.
cpu
Benchmarking shows the pi4 CPU to be several times faster than the pi2, and I believe it. Performance is so much better I changed my post-recording script (normalization, error-dropping) to no longer exclude HD files. I then queued up the existing HD files for processing.
HDTV playback
It plays 1080 recordigs back just fine. I no longer need to juggle HD files to the laptop for downsizing, or stream to a more capable display device (phone or laptop).
recording
Unfortunately I am in a rural area for the winter with no OTA in range of my flat-panel ant, so I can’t test the ability to record HD and play it back in real time (live football games or whatever). But this wasn’t a problem even with the pi2; it could be recording two HD shows at once and still stream HD to another device.
conclusion
I’m entirely happy with the pi4 and MythTV is almost perfect for my use case. The only thing on my wishlist would be Kodi-style subtitle downloads.