TV preview requires timeshift? (1 Viewer)

[htpcoz]

I find that channel changes with timeshift off are < 1 sec, almost immediate, whereas with timeshifting on is typically 5+ seconds, which is borderline unusable, in my case these long delays started around the time of RC2+CVS.

I can't really understand why TS should add such a long delay, it seems to be different for different users however, and might be related to the type and frequency of stream information being sent by the broadcaster, I can't see how it's related to the hardware if channel changes are very quick with TS off.

Hoping to get some time soon to trace exactly where the delays are.

 

[RubaDuck7]

Here are my 2 cents.
Remember I haven't seen any of the MP code, so I don't know how things are built at the moment and what is easy or hard to improve on. So I may have assumptions which are horribly wrong. Also, I'm out of town, away from my HTPC, at the moment, so some of this stuff I can't verify.

I agree with what was said here earlier;
Yes, timeshifting is one of the great benefits of using a HTPC in the first place. BUT as the current implementation slows down channel changes to the point of being borderline unusable for most (if not all) people, it's understandable that people turn it off. Since you can still pause the show you're watching at any time, the main benefit of timeshifting seems to be covered anyway, without toggling the 'Timeshift' button. Having it turned on only seems useful if you suddenly want to rewind the show you're watching or record the whole thing from the start after you have watched it fore a while? Are there other uses?

Another concern I have with Timeshift constantly on in MP is that you're constantly writing to the hard disk while you're watching TV. In most homes the TV is on for quite a few hours every night, so your disk would be working considerably more than during 'normal' PC usage. So your disk wears more quickly and the risk of early failure increases accordingly.

The way Timeshift currently slows down channel changes leads me to believe that what happens is that MP starts writing a file and then afterwards starts displaying it. So it's the creation of the file and then loading/streaming it for display which makes the delay happen?

Here's an idea. Assuming Timeshift is on, and the channel is changed, is it possible to:
First handle the channel change as fast as possible and start displaying the new channel. THEN start recording into the timeshift buffer file? So you're always watching the live stream, not the file. This implies that the same stream is sent to two destinations, the display and the buffer file. Even if this leads to recording starting a few seconds after the channel change, I don't expect this to affect anyone negatively. Rewinding and recording the whole show would still work.

Regarding the TV preview; I think it's fairly established by now in most HTPC software that if you're listening to music, watching TV, a DVD movie, video file or whatever, the playback should continue until you explicitly stop it or start playback of something else. To allow you to navigate the HTPC's UI while playback is happening, the small preview is used. Watching TV is no different in this regard, i.e. the preview should always be available until the person with the remote decides to do something else.
I agree with Waltz, in some cases you just have to allow people to choose their settings. The hard part is keeping the number of settings down so that new users can get MP set up easily. Then you still have to decide which of the settings you have left go into the configuration utility and which ones you actually want to be able to toggle with your remote. Personally, I prefer the main UI to be as simple and streamlined as possible, keeping all the 'geek' settings away from the wife's critical eyes.

Man, this got a bit longer than expected. I gotta go put my hands under some cold water.

Have a nice weekend, guys, and everyone in the Nordic countries, enjoy Midsummer!

 

[CHli]

Nice in theory but I think this is not possible atm (about the Timeshifting channel change process) because they are using the Microsoft SBE and I don't think they have much control on how it works. :?

:roll:

 

[RubaDuck7]

Anyone else have any comments on the above?

CHli: Do you know this for a fact? I don't know what the current limitations are, so I can't tell myself. It just seems that the behavior I described is pretty much what would be expected by most people anyway, so not enabling it in the underlying Windows SDK would be strange. Also, are you involved in the development of MP or 'just' an experienced user? It would be interesting to get a comment from someone working on the TV functionality, assuming they have time at the moment.


Pausing the current TV show when Timeshift is not enabled does indeed start recording/timeshifting. Sadly the screen goes black for a while, when the recording is starting up, I assume. The picture should of course just freeze on the current frame.

Also, there seems to be a logical (not technical) bug in the current implementation of the Pause behavior as well. When the current show is paused, the Timeshift setting is enabled and stays enabled. This is clearly wrong as at no point did you ask for it, just to pause the current show. Since it also brings with it all the negative side-effects (slow channel changes etc) it should be improved. Otherwise people have to always explicitly find the setting and turn it off after using Pause.

A simpler, better behavior is to start recording/timeshifting when Pause is pressed, but then turn it off if the channel is changed or you fast forward to the 'real-time' position.

Also, if the TimeShift setting really is used as described above by most people, i.e. all the time or not at all (just using Pause) the button could be removed from the TV view and the setting only be available in Settings. Please correct me if I'm horribly wrong on this last one.

 

[RubaDuck7]

The same thing seems to apply to running a fullscreen TV picture behind the MP UI.

Overall, the preview windows apparently requires a *file* to play in order to work. This makes little sense when watching TV. If you can show a small TV preview within the TV pages (EPG etc) it should pe doable elsewhere.

Any developer care to comment on this? Is it just small bug, or a limitation of the current engine?

 

[Elvar]

I know as little about the timeshifting engine as RubaDuck7, but I agree with him pretty much on everything he has said in this thread.

I'd like to tell you guys my proposition to the timeshifting behaviour. I think that when a user enables TS from the mytv window, MP should stay timeshifting as long as the user disables it from mytv. So channel changes etc. wouldn't disable timeshifting.

On the other hand, when user enables TS by pressing pause there are two possible ways to behave I think. When user starts to watch the paused program, what actually happens is that MP starts to play a recording. So when user presses stop button, the playing and timishifting should end. There is no way to change channel when you are watching recording. This would be the first way.
Other way would be similar, but there could be a preset time (user configurable of course) for TS so that MP would record the current channel for the preset time. When user presses stop, MP would start showing real time tv but still continue recording the show on background for the preset time.

These were my small thoughts for this issue. Anyone agree?

-Elvar-

 

[RubaDuck7]

Apparently nothing much has happened on this front.
Who is the primary implementer of TV UI functionality these days? I just find it strange that while it's possible to show a preview in the TV guide, for instance, the same thing hasn't been achieved in the home screen etc?!

I wish I could fix it myself, but I'm not enough of a C# guy.