Debugging / Watch TV on mpeg2 capture card

depontius · Advocate Joined: 05 May 2004 Posts: 3509

I have an HVR-1600 capture card, and it works find under MythTV - at least the NTSC side, getting fed from Comcast cable. I haven't been able to do much with the ATSC side yet, for lack of a known-good signal. For the moment I'm just concerned about the NTSC side, and debugging new capabilities. MythTV isn't the place to debug new stuff - except for MythTV.

I also have an extra Cable box, and would like to connect it to the svideo input of the HVR-1600, then go on to see what I can do about getting the blaster working, etc. But this brings up the whole issue of debug. The classic "TV applications" under Linux like xawtv or tvtime don't work well with this card - or other mpeg2 capture cards. I can get live (or slightly buffered) TV with mplayer, but that doesn't really have good/simple mechanisms for controlling the card - I'm left looking up MHz for channels, browsing multipage every-option-on-earth man pages for a few simple options, etc.

IsThere a simple set of TV watching utilities that will work with an mpeg2 capture card that doesn't force the steep learning curve of raw v4l2-ctl commands? It has been hard/impossible find the time to sit down and really learn what v4l2-ctl can do, so I'm looking for something simpler and more accessible. I'd also like to spend my time and effort on getting the HVR1600 IR blaster to work, which is a known non-trivial thing, rather than working hard to just watch TV.
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Drone1 · Posted: Wed Apr 08, 2009 8:01 pm Post subject:

sure...... at shell, run

depontius · Advocate Joined: 05 May 2004 Posts: 3509

I've been doing that. I also used v4l2-ctl to change frequencies, inputs, etc. It would just be a heck of a lot nicer if I had a frequency table handy. Cumbersome, but workable.

Current problem... I couldn't get the "spare" cable box to talk upstream and load itself. My video stuff is back of a distribution amp that claimed to be bidirectional, for this very purpose.
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Drone1 · Posted: Thu Apr 09, 2009 6:22 pm Post subject:

Should be able to get current frequency table with ivtv-tune....

I'm using ivtv-tune and v4l2-ctl in some scripts with irexec (under lirc) to change channels for VLC, since CH+/- doesn't exist under VLC. Specifically, I pull the current freq with v4l2-ctl (I think, currently at work, so scripts aren't in front of me...) match that against a frequency table file (that was generated using ivtv* command), where I pull out the current channel, increment/decrement by 1 depending, and then send that number against ivtv-tune -c . Found some other scripts online to do it, but those used way too much code..

As far as the spare cable box, you should be able to cycle through the inputs for the card using the aforementioned command utils.... You sure that distribution amp is bidirectional? That seems contradictory to me. I may not be understanding your setup correctly, however.....
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depontius · Advocate Joined: 05 May 2004 Posts: 3509

I'm using the HVR-1600, which is ivtv-like, but not ivtv. I've had the ivtv stuff installed in the past, partly out of confusion of thinking that the cx18 drivers were layered on top of the ivtv drivers, and partly to see if I needed the utils. I've also had various vintage/upgrade problems with them, so I'm not sure if they're installed at the moment. This will all have to wait until I have another burst of spare time.

The distribution amp specifically stated that it had the bidirectional return path. The return path is on a different frequency range, so it shouldn't be a difficult thing. Now that I think of it, there's a "strength" knob that hasn't seemed to make much difference. I've tweaked it a little, and never seen any difference - I should fiddle more extensively with it live. I know that I've been able to use v4l2-ctl (or something) and get a signal strength number, which has always been 99% or some such, pretty much no matter what I do. Now I'm wondering if that knob is for the return signal strength, in which case keeping it at minimum (which is where it is now because I didn't want to swamp my card front-ends, and they worked at minimum) means no return signal from the cable box to the cable company, hence no proper boot.
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