Very slow tune after trying off-air channel (1 Viewer)

[doveman]

MediaPortal Version: v1.1.0 Final
MediaPortal Skin: StreamedMP
Windows Version: XP Pro SP3
CPU Type: Athlon II X4 630
HDD: 640GB WD SATA
Memory: 4GB DDR2 1066Mhz
Motherboard: Biostar TA790GXB3
Video Card: HD3300 IGP
Video Card Driver: 10.5
Sound Card: onboard Realtek AC97 (ALC662)
Sound Card AC3: no AC3
Sound Card Driver: 5.10.0.6101
1. TV Card: Hauppauge Nova-T 500
1. TV Card Type: DVB-T
1. TV Card Driver: 4.3.27240
MPEG2 Video Codec: Cyberlink Video Decoder (PDVD9)
MPEG2 Audio Codec: ffdshow
h.264 Video Codec: ffdshowDXVA
Satelite/CableTV Provider:
HTPC Case: Custom
Cooling: Nexus 120mm Intake Fan, Stock CPU HSF
Power Supply: EZCool 450W
Remote: Nova-T 500
TV: Sony XBR800 36"
TV - HTPC Connection: DVI

I accidentally selected BBC3 from the TVGuide whilst it was off-air (at 13:17:30), which obviously didn't work. That took about 8 seconds before MP told me it couldn't find a signal. Then I accidentally did it again! (13:17:50-13:17:58). I wonder if this process can be sped up at all? I notice in tvserver_tv.log that it did the "find free card for channel" three times, although each time only took 14 msec, so changing that wouldn't make much difference. It actually detected that there was "no audio" within 3 seconds, but then proceeded to try my other tuner, which took a further 5 seconds. As I've got a dual-tuner DVB-T card which uses one aerial, if it can't find a signal on the first tuner it won't find it on the other, so there's really no point in trying and if I could disable this, it would greatly speed things up for me.

Then I selected BBC1 (13:18:01) and it took 28 seconds before it came up, so something must have gone very wrong there.

 

[jameson_uk]

This has been the case for many years and is a right pain as normally when you select BBC3 it locks up your machine until it tells you it can't do anything...

AIUI the issue is that stuff is being transmitted (when it is off it is just the MHEG5 screen telling you it is not on) so MP picks up a stream and then goes through the steps to pick up the video signal. This needs to happen for channels which might take a while to tune etc.

I think in the past this has been classed as a feature and not a bug. Going to go through some old documentation on this

 

[tourettes]

You can reduce the timeouts for tuning in tv server config. This will reduce the time for waiting, but complete cure would require big changes into the tv client / server (whole channel tuning etc. would need to be made asyncrhonous).

 

[doveman]

I can understand MP can't tell that BBC3 isn't actually transmitting programs as it transmits a signal constantly.

The problems with MP however are:
1) it checks both of my tuners, one after the other. I want to stop it doing this. Is it not something fairly easy to change?

2) There's obviously a bug which caused MP to take 28 seconds to tune into BBC1, although this has never happened to me before as far as I recall, so I can understand if the devs don't see it as important.

3) I've already got the "Wait for unscrambled signal" and "Wait for timeshifting" set to 1 second. I had a discussion with Paranoid Delusion about why these settings didn't seem to be reflected in the time MP takes to decide there isn't a signal, but it didn't really go anywhere. https://forum.team-mediaportal.com/...s-up-tuning-weak-tv-channel-81070/#post608568

I don't know what the Scanning settings on the General tab in TVServer config are for, or whether changing them would make any difference, so if anyone could advise that would be appreciated.

 

[glenn 1990]

Here are the timeshift setting working as expected.
If I tune (with a dual tuner) to an off-air channel, it takes about 5 second before I get "unable to start timeshift"

I think that "Wait for unscrambled signal" and "Wait for timeshifting" are set on 2 seconds or so.

 

[tourettes]

I think there might be two different cases:

1) channel is tunable, but no video & audio content is sent
2) channel is no tunable

The 1st case would probably have the hard coded 15 second detection time for A/V streams (at least this was hard coded when I did work on that area few years ago). And the server probably will try to tune all available cards, since the 1st card could just be broken, signal cut off, no cable etc. That would results approx 30 second freeze if the channel is aired, but contains no A/V streams.

Sollution for that would be to allow user to specify the A/V stream detection timeout.

 

[doveman]

No,no,no!

It took 8 seconds, 3 of which was for my first tuner and 5 for the second. So if I could set MP to only try to tune with one tuner, it should bring the time down from 8 seconds to 3.

As I said, it doesn't make any sense for MP to try two tuners in my scenario, because they're both on the same card, so if the aerial cable's broken, neither tuner will be getting any signal.

Nothing to do with the above problem, but I've got my "wait" settings both on 1 second and if I try to tune to an actual off-air channel, it only takes about 3 seconds. I think I probably sped this up by changing the Tune settings under General-Scan from 2 seconds to 1 second. Since then, tuning into broadcasting channel seems to happen a lot quicker now as well.

 

[wonkyd]

No,no,no!

It took 8 seconds, 3 of which was for my first tuner and 5 for the second. So if I could set MP to only try to tune with one tuner, it should bring the time down from 8 seconds to 3.

As I said, it doesn't make any sense for MP to try two tuners in my scenario, because they're both on the same card, so if the aerial cable's broken, neither tuner will be getting any signal.

Trouble is MP doesn't know that your two tuners are in fact one, as the operating system considers them to be separate.

The problem comes with say in the UK you have a DVB-T tuner and a DVB-S tuner and you wanted to watch the Community Channel (pfftt!). On DVB-T that channel only broadcasts for 2-3 hours yet on DVB-S it's 24hours. If MP only tried the first card and you had set it to DVB-T you wouldn't be able to tune to that channel outside those 2-3 hours. A setting like that would have to be user configurable at least.

The 1st case would probably have the hard coded 15 second detection time for A/V streams (at least this was hard coded when I did work on that area few years ago). And the server probably will try to tune all available cards, since the 1st card could just be broken, signal cut off, no cable etc. That would results approx 30 second freeze if the channel is aired, but contains no A/V streams.

Sollution for that would be to allow user to specify the A/V stream detection timeout.

That would make sense seeing as my machine can take up to 30 seconds if BBC THREE is off air as I have three tuners.

Would it be a simple task to add a user defined time out i.e is it something we could sweet talk you into doing?

 

[tourettes]

As I said, it doesn't make any sense for MP to try two tuners in my scenario, because they're both on the same card, so if the aerial cable's broken, neither tuner will be getting any signal.

Unfortunately that kind of topology information is not available for the tv service (at least I don't know how it would be). Also it is even possible to have one one tuner broken in a dual tuner card.

 

[tourettes]

That would make sense seeing as my machine can take up to 30 seconds if BBC THREE is off air as I have three tuners.

Would it be a simple task to add a user defined time out i.e is it something we could sweet talk you into doing?

Currently nothing since I'm spending all the MP "freetime" with the audio renderer (who knows how long that journey takes...). Previously I did the mistake that I was touching almost every part of MP1, now I'll try to focus one part at the time.