MythTV - 4 simultaneous encoders from 2 tuners (hdhomerun)!

[donpaul]

I was mucking around with Mythtv, and broke it. In my efforts to fix what I did, I now have 4 encoders from a single hdhomerun box. I had thought I screwed it up again, but was curious and set 4 shows to record. All 4 shows recorded successfully. Needless to say I was thrilled. I did a bit of research and found that mythtv can take advantage of multiplexing.

Has anyone else noticed or taken advantage of this. And shouldn't LinuxMCE set up multiplex when installed?

[tschak909]

Yes, but at least I am unsure of what to set to properly enable this.

-Thom

[donpaul]

I also wonder if I could get more than 4, but I am too chicken to try I made the mistake of telling the wife, and she threatened me when I mentioned messing with it some more.

[los93sol]

use clonezilla to back up the current working state of that box then feel free to hack away, if it breaks restore your image and your back where you started.

[totallymaxed]

I was mucking around with Mythtv, and broke it. In my efforts to fix what I did, I now have 4 encoders from a single hdhomerun box. I had thought I screwed it up again, but was curious and set 4 shows to record. All 4 shows recorded successfully. Needless to say I was thrilled. I did a bit of research and found that mythtv can take advantage of multiplexing.

Has anyone else noticed or taken advantage of this. And shouldn't LinuxMCE set up multiplex when installed?

The HDHomerun is supported as a multirec capture device in 0.22. Just set the multirec tuner setting to >= 2 (upper limit is 5 i believe in an unpatched backend) for each HDHomerun capture device in Myth-backend setup.

All the best


Andrew

[merkur2k]

note that multirec depends on the programs being on the same physical channel. ie one is on 4.1 and one is on 4.2.

[tkmedia]

You can set the number of virtual cards.... you get two by default, from my understanding you can record as many shows as you have virtual cards provided they are on the same mux.
Nothing special required to use them other than channels to be recorded being on single mux per physical tuner





Tim

[donpaul]

note that multirec depends on the programs being on the same physical channel. ie one is on 4.1 and one is on 4.2.

I recorded 4 different HD shows from four different networks (5.1, 11.1, 17.1, 50.1), and they all recorded fine. So not sure if what you stated is accurate.

[tkmedia]

(5.1, 11.1, 17.1, 50.1)


my guess is  5.1 and 50.1 are on one mux  and 11.1 and 17.1 on another

since you have two physical tuners in worked fine with that combination.

Tim

[totallymaxed]

note that multirec depends on the programs being on the same physical channel. ie one is on 4.1 and one is on 4.2.

I recorded 4 different HD shows from four different networks (5.1, 11.1, 17.1, 50.1), and they all recorded fine. So not sure if what you stated is accurate.

Multirec works as follows;

A bundle of Digital TV channels are broadcast on a given frequency - ie they are multiplexed together into a bit stream on that frequency. When you request Channel 10 Myth chooses an available Tuner and tunes to the frequency/multiplex that Channel 10 is broadcast on and it extracts the channel 10 stream from the multiplex on pne of your 'free' multirec virtual tuners. Now if you choose to watch or record a second TV channel on say Channel 30 the same process happens...except this time Channel 30 is on another frequency/multiplex. So now we have both physical tuners deployed delivering channels from two separate multiplex's. In this situation while we are watching Channel 10 & 30 we can also record up to 4 other channels on either multiplex...but we cant watch/record any channels on other multiplexes until we free up one of our physical tuners so that it can be tuned to that frequency/multiplex.

Hope the above is useful.

Andrew

[tschak909]

Keep in mind that the channel that's sent via the PSIP is often NOT the same as the raw channel on QAM256 cable, so while you may have different channel #s broadcast by the PSIP (4.1, 5.1, 25.1, etc.), they may all be on QAM channel #82.

-Thom

[merkur2k]

the easiest way to see what "physical" channel they are on is looking at the hdhr channel lineups web page.