For a long time everyone has suffered shocking TV reception at the units where I live. Sometimes it's crystal clear, then channels randomly disappear for a week or so. We've put it down to being in a black spot, the antenna being crap, the wiring being crap, trams and various other causes (maybe the piano interferes...!?)
A month or so ago, one of the residents, Mary, got fed up and called an antenna guy to come and have a look. He actually knew what he was doing and diagnosed the problem to be that signal booster #1 was sending far too powerful a signal into booster #2, making booster #2 overload and fail.
Installing a simple resistor to lower the signal going into booster #2 resulted in perfect reception on all channels and no artefacts when a tram went by.
I just decided that since reception was such a problem when I switched from my DViCO card to the LeadTek, I should now install both and try them side by side.
As of about an hour ago, I have three tuners, each of which is capable of recording two simultaneous streams. I think the raid array wouldn't cope if it tried to record six shows at once, but then again the chances of there being six simultaneous programmes worth recording is zero.
I can now at least record shows on both the ABC and SBS at the same time and still have a tuner spare for the odd occasion there is something worth spending time watching on channels 7, 9 or 10.
Yay!
Comments
disk io
you might be surprised at how many simultaneous shows your myth box can record.
unless you've got really slow disks in (even slower) RAID-5 on an already overloaded system, recording six simultaneous shows should be no problem. recording 6 HD channels might be a problem, but SD wouldn't be. The IO requirements aren't actually that high for SD or even HD, not compared to what hard disks are capable of.
I've got two dvico dual-tuner cards in one of my myth machines, and another myth box has a nova-T 500 plus two old single-tuner cards (i bought a bunch of old cards as a cheap bundle on ebay and their main purpose is to support live tv just in case something is being recorded on the newer dual-tuner cards). each tuner is set up for up to three simultaneous recordings (helps with overlapping programs) but in practice are unlikely to be recording more than two shows out of a stream. so each machine can theoretically record 12 simultaneous programs (up to 3 programs each on 4 different transponders).
anyway, i've had no difficulty whatsoever recording 6 or more programs simultaneously (some nights there's lots of overlap between programs i want to record - i schedule recordings for 10 minutes before and 15 minutes after, which is especially important on the commercial channels).
i've even deliberately tested the setup by setting them to record every program currently showing. IIRC that was about 11 simultaneous recordings (ABC 1,2 and HD, SBS 1 and 2, and 7,9,10 both SD & HD). both machines had no difficulty at all with that.
this setup has no difficult doing this even while transcoding several other shows at the same time.
BTW one of the machines is my combined workstation and home server (mail, dns, web, ftp, squid, postgresql, mysql, and a bunch of other stuff). both machines are also acting as NFS servers to share myth video directories with each other and with myth frontends.
i routinely have 2 or three shows recording (i record a lot of crap i never get around to watching. also i watch TV in batches when i've got nothing better to do and like having hundreds of programs to choose from at any given time) and commflagging while older shows are being transcoded - the commflag and transcode jobs could be running on any of the machines on my home network (4 debian boxes) as they all have myth-backend installed for processing the job queue, so there's a lot of disk and NFS I/O.
at first, i deliberately avoided doing IO-heavy things (like apt-get upgrade or transcoding) while recording shows. now i don't even think about it...i've learnt from experience that it just doesn't matter.
related thread on mythtv-users list
BTW, see also the mythtv-users thread starting here http://mythtv.org/pipermail/mythtv-users/2009-July/260780.html
the third message in that thread mentions that with 4 DVB tuners in australia, peak bandwidth usage is about 120Mbps.
Re: disk io
I had some overlap last night and the machine happily recorded three streams at once. I didn't check the load, though.
The machine is getting a bit long in the tooth; it's an Athlon64 3000+ and it only has 512MB of RAM. However, disk access should still be fairly quick, as I'm running md raid0. (I know it's a bad idea, but I'm not worried about the loss of a day or two of tv shows)
I actually just got word I inherited some small form factor cases, so I might be able to relatively cheaply upgrade the machine to a low end core 2 duo soon and not have an ugly beige power case in the living room anymore.
Multiple Recordings
I was thinking of getting a 3rd tuner. And was worried about disk io bandwidth.
The problem is how to stop it recording the same show at the same time on two channels.
IF I set it to search for one a day I miss back to back shows. If I set it to find any It will record one show twice ( one SD and one HD ) but then miss lower priority show altogether. What I need is a search and record one at a time in any channel, is this possible.
Re: Multiple Recordings
I tend to choose "At any time on this channel" as recording option, unless the show is a once-off or movie. That way it'll grab back to back shows, but not for instance record it on an SD as well as HD channel.
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