out from under the canopy, mythtv
wide-open solar
I looked at solar harvest this morning at 0802; the system was making 110w. This is why I prefer open spaces.
Plenty of harvest potential, so I made coffee and egg & bacon breakfast burritos on the mini-hotplate. The fridge is full so I’ll eat letovers for lunch and dinner.
MythTV on the Pi2
My El Cheapo homeworx dvr was getting flakey and died. I was glad because I wanted the motivation to rebuild a pi-based MythTV setup. I killed the last one by upgrading and won’t make that mistake again.
which Pi?
I have a Pi2 which is underpowered for the job. And a Pi3 that would be better but it abso-freaking-lutely refuses to output video to HDMI. Yes, I’ve tried different cables, power supplies, and monitors.
So Pi2 it is. I stayed up late getting it running on Buster (Debian 10) and Myth 32.
success so far
It’s only been a few hours but it’s stable, records correctly, and plays SD just fine.
As I alluded to earlier, the Pi2 is a bit weak and cannot play HD smoothly while doing other things.
So I watch HD streamed to other devices on the network (phone and a $10 thrift store tablet). The Mythling myth frontend for android isn’t elegant but it works. I might use it for SD as well if the killer feature were supported: *delete and allow re-record”. On the native frontend this option
- deletes the recording (naturally)
- but also deletes the episode info from the database
Basically it’s as if Myth has never seen it before and records it again. Hopefully we get better reception next time.
HDHR-US2 dual tuner
Way back in v27 (?) of myth the two tuners in this device were named distinctivley, like [serialnumber]-0 and [serialnumber]-1. Now they look exactly the same when you add both. But it works. Ihe 2nd shot at the top of the section you can see both tuners represented. You can also see I accidentally set them up differently; the first has 3 virtual tuners and the second only 2. These virtuals work because digital OTA is usually multiplexed.
multiplexing
Let’s say we have a station on channel 5, with these subchannels
- 5.1 main HD 1080 channel
- 5.2 SD weather channel
- 5.3 SD community acess
These are all being sent on the same signal (“channel” 5) and so it only takes 1 tuner to theoretically record some or all of them at once. In practice we might not get this “freebie” often, but the screencap shows the top tuner recording two streams of the same signal (“2 recording”).
A side effect of this “send it all on one signal” approach is the broadcaster can pick which streams get what share of the bandwidith. They might just have 2 subchanells (one 1080hd and one 720hd), or a mix of HD and SD, or all SD. In the latter case I’ve seen up to 7 SD subs on the same signal. I don’t know if there’s a maximum.
Each commercial broadcasting terrestrial television DTV channel in North America is allocated enough bandwidth to broadcast up to 19 megabits per second. However, the broadcaster does not need to use this entire bandwidth for just one broadcast channel. Instead, the broadcast can use Program and System Information Protocol and subdivide across several video subchannels (a.k.a. feeds) of varying quality and compression rates, including non-video datacasting services. - wikipedia