Recording Quality, where has it gone?

[hasso]

Likewise can also watch LiveTV and record the same digital channel on the same tuner.

mmm... I thought Live TV couldn't share a tuner. Has that changed?

[mvallevand]

mmm... I thought Live TV couldn't share a tuner. Has that changed?

I've had a PC, an NMT and a PC client all watching LiveTV on the same digital channel from the same tuner completely independently.

Martin

[Sykor]

I have been having problems with poor quality recordings because one tuner is recording two shows at once, leaving open tuners unused. I have tracked back and can confirm this is the cause of the poor quality. So I thought I would go back and set each recording to have the "best quality" to hopefully help "push" it to another tuner. I could of sworn that there was a setting for recording quality by program (as well as a default), but when I go in to update and even record anew, I can not find this. Is it my imagination, has it been removed in the latest patches...???

If you're talking digital. NPVR records the feed as it gets it, no changes whatsoever. No amount of tuner alternating will help you if the signal's quality is poor. But, since I suppose you're talking about the analog side of your tuners:

IIRC when it comes to analog recordings, you can jump around "poor/medium/high/best" quality settings all you want... Regardless of your chosen option, NPVR uses only _ONE_ setting. The one specified under <Analog> in config.xml

Example (my setting for my PVR500)

Code:

<Analog>
  <Bitrate>5500000</Bitrate>
  <BitratePeak>9500000</BitratePeak>
  <BitrateMode>VBR</BitrateMode>
</Analog>

I guess NPVR tries to reuse the tuner's/encoding output when recording consecutive shows, so there shouldn't be any quality drop, be it one or more shows. Change the default values in config.xml, and check the next recordings to see if that was the problem. The default setting is somewhat conservative.
On a side note, my PVR500 also needs it's built mpeg encoder settings tweaked, as the default settings output less than decent results in terms of colour/brightness/etc. And being a dual tuner, maybe the two analog tuners/encoders installed/used are from different sources/makers. In my case, they are. Try changing the source's priority, and see if the recordings' quality improves.

If this feature is no longer available, does anyone have any idea how I can force the recording software to utilize all my tuners before doubling up on one???

GBPVR had a "PreferAlternateTunerSource", to do just that (only doubling the same tuner, if no other was available), but no implementation of that was done with NPVR, and I do believe there won't be one.

[TVHelp]

First let me apologize for not responding earlier to any of these posts...I did not get an email stating that there were any responses. Thank you everyone.

If you're talking digital. NPVR records the feed as it gets it, no changes whatsoever. No amount of tuner alternating will help you if the signal's quality is poor. But, since I suppose you're talking about the analog side of your tuners:

I am talking digital. I ONLY have digital channels set up, but am I sure I saw a quality setting when I scheduled a recording..? Oh well. Sounds like this does not matter for digital anyway.

I guess NPVR tries to reuse the tuner's/encoding output when recording consecutive shows, so there shouldn't be any quality drop, be it one or more shows. Change the default values in config.xml, and check the next recordings to see if that was the problem. The default setting is somewhat conservative

No analog here, so the default will not help..

I am seeing multiple digital channels being recorded on one tuner at the same time. If it was just the timer overlap I would be happy with that, but the channels that are being recorded are high def and some of the channels need to be exclusive or the signal degrades - NBC and CW broadcast at 1080i and those are the ones that really create problems. Usually a 720p broadcast is Okay. I can see in the logs that the quality can drop to 60 when two shows are on one. Since there are open tuners I would like it to just move to another tuner...

I have verified this issue by recording one show, then half way through adding a second recording for another channel, watching it pick-up on the same tuner and then I check the recording to see that choppy signal quality is realized for the second half of the first recording only. There can be no doubt as to this affect as I can repeat this result.

[QUOTE=Sykor;425323
GBPVR had a "PreferAlternateTunerSource", to do just that (only doubling the same tuner, if no other was available), but no implementation of that was done with NPVR, and I do believe there won't be one.[/QUOTE]

This would be what I am looking for With the option when I do need to record more than the tuners I have, then overlap, but this would be an intentional action on my part to over-extend my recording capacity.

[TVHelp]

I think you can go to Devices setting to set the device priority.
#1 #2 belongs to first 2250 tuner while #3 #4 belongs to second 2250 tuner, right?
Maybe can up the #3 to second slot above #2?

Correct on the setup.

I have made an attempt to change tuner order, but it really does not seem to matter, as the signal is perfect up until the tuner gets 'over-used'.

I have even tried to remove some channels from one tuner and not others, but got myself stuck with the software not finding a tuner when needed - I can't really follow the logic of how it works. It seems to have pre-defined tuner usage but then starts jumping around at actual recording time and the pre-defined tuner usage does not take into account any removed channels or tuner reordering...???

In addition I have experience the recording service crash a few times and am not sure if it is due to the remove of certain channels from some tuners or not so I am hoping to avoid that solution.

Basically the problem occurs when digital channels share the same main frequency/physical channel, but just have a different sub frequency/service id. So the tuner will just go ahead a record them together on one without bothering to check for more....

[Reddwarf]

The problem seems to be that your input signal is not strong enough to feed two tuners at the same time. Maybe adding an amplifier on the antenna-side would help?

[Lao Pan]

@hasso

mmm... I thought Live TV couldn't share a tuner. Has that changed?

Since the advent of NPVR

@ TVHelp

In digital broadcast streams all the channels on an individual mux are sent to the software (NPVR in this case) all of the time. It is then the software that splits the channels that are requested - discarding the rest. If the channels you require to record are on different muxes a second tuner will be used - there is no point in using 2 tuners for the same mux.
Your problem must be coming from either NPVR - have you merged HD and SD versions of the same channel? NPVR might then use the SD channel rather than the HD as it will only need one tuner.
Otherwise you may have a bottleneck somewhere else on your computer (Disc in out, Disc fragmentation or even cpu maxing out)that is causing the degradation in recordings.

In digital NPVR just gets what it is given and writes it to disk.

[Reddwarf]

I had the impression that the signal strength (logged in Nrecord.log) had decreased, so I assumed that this happened when the card kicked in the second tuner. If then the signal strength becomes too low you can have pixelisation and other interrupts (noise) in the datastream.

So to clear this up: In what way is the quality poor TVHelp? Blurry? Noisy?

[TVHelp]

The problem seems to be that your input signal is not strong enough to feed two tuners at the same time. Maybe adding an amplifier on the antenna-side would help?

Yep, already have a booster/splitter in place.

[TVHelp]

@hasso
In digital broadcast streams all the channels on an individual mux are sent to the software (NPVR in this case) all of the time. It is then the software that splits the channels that are requested - discarding the rest. If the channels you require to record are on different muxes a second tuner will be used - there is no point in using 2 tuners for the same mux.

By muxes do you mean frequencies, and if so does that exclude the sub channel? That would then explain the problem.
Given High Def, there is obviously an actual need for each of the sub channels on the same frequency to be on different tuners. Media center does not make full use of tuners either, that is why I switched to nPVR. At least nPVR could handle channel overlap so that made me happy, whereas Media center just cut off the recording to use the same tuner for the next show on that channel. It is just this last hurdle to perfection I am missing. Maybe I need to go back to Media Center and see If I get the same result - but I have to have nothing planned to record in nPVR, so the timing is difficult to manage on that one.

@hasso
Your problem must be coming from either NPVR - have you merged HD and SD versions of the same channel? NPVR might then use the SD channel rather than the HD as it will only need one tuner.
.

I have no idea how to merge HD and SD versions of the same channel. I simply deleted any analog / SD channels that were picked-up by the tuner originally, as I did not want to record the wrong one. Is it possible they merged on their own during tuning?

@hasso
Otherwise you may have a bottleneck somewhere else on your computer (Disc in out, Disc fragmentation or even cpu maxing out)that is causing the degradation in recordings.

I really don't think that I have a bottleneck on my computer - 12 core 3.4gHz i7 12Gb RAM. If anything, I have excess. In addition, when I delete channels from one tuner so as to force use of a second tuner, the picture is fine. If it was a bottleneck the picture would probably be worse when using a second tuner.

@hasso
In digital NPVR just gets what it is given and writes it to disk.

That's what I thought until I experimented and saw different results depending on how many channels were on a single tuner.