Recordings with pre- and post-roll, ATSC vs. Colossus

[Karyudo]

When I set back-to-back recordings with a minute pre-roll and a minute post-roll on a channel that I get on my single ATSC tuner, the two files come out perfectly: the first show has a minute of the show before it at the start, and a minute of the second show at the end. The second show has a minute of the first show at the start, and a minute of the following show at the end. In other words, there's a minute of airtime that's duplicated in both files -- exactly how I want it.

When I do the same thing on a channel I get on my two cable boxes and feed to a pair of Colossus cards, I get something different (and worse): the first show recording ends hard, just before the end of the show, and the second show recording starts cold, from exactly the point that the previous recording stopped. There's no overlap at all, despite there being two separate tuners and capture cards!

Why the difference? Is there any way to make the Colossus case work the same as the ATSC case? (If I can record two separate channels at the same time with this setup, why aren't the pre- and post-roll times respected?)

[Kiwi]

For the former, most likely there's no issue, that's because NPVR can record all the channels on the same frequency on a single tuner, including the same channel, whether be it ATSC or DVB.

For the latter, u probably have to ensure that u set up the Video Input to both Colossus cards in NPVR, so that both cards will be used.

[Karyudo]

For the former, most likely there's no issue, that's because NPVR can record all the channels on the same frequency on a single tuner, including the same channel, whether be it ATSC or DVB.

I don't see how that helps. I've got a single tuner, tuning one channel, on one frequency. There are no sub-channels (and even if there were, I'm not interested). I'm recording channel 22.1 (say) for an hour, recording two shows. But I'm getting two, 32-minute recordings from it, exactly as requested.

For the latter, u probably have to ensure that u set up the Video Input to both Colossus cards in NPVR, so that both cards will be used.

I am reasonably sure that's exactly how I've got everything set up already! Two cable boxes, each with a tuner, outputting via component to two Colossus cards, both set up in NPVR, both with the same channel lineup. I've sort of looked for some checkboxes to sort out how the two Colossus cards are used together, but the only obvious checkbox is for reversing the order for live TV (or words to that effect), which I haven't checked for either card.

Still stumped!

[johnsonx42]

The colossus card can only be used for a single recording at a time, even if the other desired recording is of the same content. Other tuner types can be used for multiple simultaneous recordings (such as recording padding on back-to-back shows on the same channel); this ability is usually referred to as multi-record. Pre- and post- padding is done when possible, but the logic doesn't go to great lengths to accomodate it. I suspect the current logic is predicated on the notion that multi-record is always possible, and it simply fails in your specific situation when multi-record isn't possible yet the two recordings are on the same channel. The logic of using just one tuner for back-to-back recordings on the same channel outweighs the logic trying to accomodate the padding.

In other words, you're not doing anything wrong and the software is behaving as intended. To do what you want, sub would have to add additional logic to move a recording to another tuner in order to accomodate padding.

[Kiwi]

I don't see how that helps. I've got a single tuner, tuning one channel, on one frequency. There are no sub-channels (and even if there were, I'm not interested). I'm recording channel 22.1 (say) for an hour, recording two shows. But I'm getting two, 32-minute recordings from it, exactly as requested.



I am reasonably sure that's exactly how I've got everything set up already! Two cable boxes, each with a tuner, outputting via component to two Colossus cards, both set up in NPVR, both with the same channel lineup. I've sort of looked for some checkboxes to sort out how the two Colossus cards are used together, but the only obvious checkbox is for reversing the order for live TV (or words to that effect), which I haven't checked for either card.

Still stumped!

The colossus card can only be used for a single recording at a time, even if the other desired recording is of the same content. Other tuner types can be used for multiple simultaneous recordings (such as recording padding on back-to-back shows on the same channel); this ability is usually referred to as multi-record. Pre- and post- padding is done when possible, but the logic doesn't go to great lengths to accomodate it. I suspect the current logic is predicated on the notion that multi-record is always possible, and it simply fails in your specific situation when multi-record isn't possible yet the two recordings are on the same channel. The logic of using just one tuner for back-to-back recordings on the same channel outweighs the logic trying to accomodate the padding.

In other words, you're not doing anything wrong and the software is behaving as intended. To do what you want, sub would have to add additional logic to move a recording to another tuner in order to accomodate padding.

In that case, try to key in the recording start and end times manually (using the 4 digit times keyed in using keyboard) and set the pre-padding and post-padding minutes to 0.

For example: If u want to record a program from 1pm to 2pm and wish to have 3 mins of pre and post padding, key in the time manually as 1257 and 1403.

[johnsonx42]

A manual recording is an ugly work-around at best. It will work as long as the program never changes time or channel, and of course there's no "avoid duplicates" logic. You wouldn't even get show details like subtitle or description for such recordings.

The old GB-PVR program had a setting <PreferAlternatingCaptureSources> which would solve this issue. Back-to-back recordings on the same channel would get assigned to sources, and both recordings would get padding with two colossuses (colossi? colossae?)

I've often advocated an option to make padding required. I don't use padding much, but when I do it's because I really want it. A few times it's been VERY annoying to have gone through the trouble to add padding to a particular recording I knew was likely to run long, and then find it out it didn't do it in order to record some other show I didn't give a crap about. People then say "use a manual recording", which is just as annoying as it's no solution to the problem at all, just an ugly work-around.

[Karyudo]

I don't have time right now to comment and persuade in detail (on my way to the airport!), but this sort of surprises me: I'd have thought that back-to-back recordings with no padding would be a special case where the same Colossus/tuner could be used, rather than the generic case where both tuners/Colossae (I think I like that one best...) would be needed for all other combinations of in/out padding. Because I'm with you, johnson: I specify padding because I really want it!

I also still don't get why the overlap couldn't be buffered, or written to two streams, or whatever, from a single Colossus. (I imagine sub can enlighten us as to why not!)

[johnsonx42]

I'm pretty sure it goes back to the fact that almost all other devices are able to write multiple streams at once (including regular analog tuners). So back-to-back recordings on the same channel normally would allow padding without changing tuners, and it's the multiple colossae (or hdpvr's) that is the exception which needs special handling.

[Karyudo]

Do any of you know if something like MediaPortal does recording with multiple Colossae properly? Because for me, this is essentially non-negotiable, and something I'd dump NPVR over.

sub, is johnsonx42 correct in saying the Colossus is different from every other card (including analog capture), and can't write multiple streams? If true, that's astonishing. And there are no plans to provide for this weirdness by tweaking the recording/scheduling parameters to use multiple Colossae to ensure properly padded back-to-back shows on the same channel? That would be truly a shame, considering how delighted I was that NPVR did way better than Windows Media Center at padding ATSC recordings properly.

[sub]

I dont know what MediaPortal does with the Colossus/HDPVR recordings.

Basically I've only added this feature for digital cards, since these are usually receiving more than one channel per frequency they're tuned to. In DVB parts of the worlds its very common to be recording more than one of those channels at a time. A lot of DVB countries only use 3 or 4 frequencies for all their channels. This feature does have added advantage of being able to overlapping pre/post padding if the tuner stays on the same frequency.

I didn't add recording multiple streams simultaneously for the Analog/Colossus/HDPVR devices, because it would have been of much more limited use. ie, these devices can only ever be tuned to one channel at a time. It could be of some use for the overlapping pre/post padding, but only if the recordings were on the same channel. It didn't seem worth the effort for such limited advantage.