[TV] more consistant Fastforward? (1 Viewer)

[Benoire]

Evening lovely MP Devs

I recall asking this a while back and the answer I got was due to the many filters that could be used it would be hard to get this to work (unlike XBMC and WMC which use a non user changeable filter). Now that the LAV filters appear to be the default filters for playback, is it possible that fastforward rather than skip might be more consistent if you use LAV? Perhaps I'm barking up the wrong tree and it is something completely different but I really do miss a decent ffwd like x15 and x30 that actually work (imagine sky box!).

Is it possible under the current architecture?

Cheers,

Chris

 

[mm1352000]

Fast forward is often implemented as playing at the given speed. I can't imagine that anything but the most powerful hardware would be capable of playing h.264 at 30 or even 15 times normal speed. I note that the MS codec implements a fast decode mode:
http://msdn.microsoft.com/en-us/library/windows/desktop/hh184791(v=vs.85).aspx

If not already used, this info/property could be used to improve the implementation.

 

[Benoire]

Hey mm,

How does WMC carry out the fast forward as I was able to do this quite easily when I was trialing DVB link as a method of playing from a central place... I'm not interested in sound for example, just the ability to ping through adverts at x12 or something as skip always makes me miss the beginning of the next part of the program.

Obviously the sky boxes (both UK and here) have x2, x6, x12 and x30 which are actually these and you can see the picture spinning along at a much higher frame rate... but I'm more curious as to how XBMC gets this going as well as wmc.

 

[mm1352000]

...as skip always makes me miss the beginning of the next part of the program.

At least on Freeview, ads are 3:45. Skipping 3:30 pretty much guarantees no problems.

Obviously the sky boxes (both UK and here) have x2, x6, x12 and x30 which are actually these and you can see the picture spinning along at a much higher frame rate... but I'm more curious as to how XBMC gets this going as well as wmc.

I'm not an expert on this. You need Owlsroost and others who know about playback. My guess: slower modes are implemented as full fast playback; faster modes are implemented by only decoding/rendering I frames.

 

[Benoire]

At least on Freeview, ads are 3:45. Skipping 3:30 pretty much guarantees no problems.

Most likely with TVone actually only playing 5 minutes of program per ad-break :-P I swear The Mentalist the other day had ad then 5 minutes of actual show!

@Owlsroost is it possible to have your thoughts on this if you have the time?

 

[Owlsroost]

I recall asking this a while back and the answer I got was due to the many filters that could be used it would be hard to get this to work (unlike XBMC and WMC which use a non user changeable filter).

That would still be my opinion, basically. Some decode filters and splitters don't even properly support what MP does at the moment, let alone anything more advanced, so MP does a simple 'play all frames faster' up to (I think) x4 speed, and then drops back to using 'fast skip' auto stepping above that speed. Most video decode filters can handle up to x4 without getting into too much trouble so that seems to be a good 'lowest common denominator' setup.

I spent quite a lot of time improving/fixing FFWD/RWD a while ago - we don't get that many complaints about it now so it's not on my radar to do any more work on it (but volunteers are always welcome ). Like mm I always use skip steps to move around in a recording.

 

[Benoire]

Hey Owlsroost, thanks for the reply

Would there be any benefit in simply forcing MediaPortal down a single filter route (such as LAV)? Ignoring the obvious lack of choice and potential conflicts, would this allow refinement of many of the playback options, or am I simplifying it too much?

Honestly, I'd love to give this programming malarkey ago, unfortunately I've tried and I simply cannot get my head around C# at all... I'm a Civil Engineer and logic comes naturally to me but hell the way the code is referenced really has me confused!

I'd love to see further improvements to FFWD/RWD but understand that the want of one is out weighed by the want of the many (etc. etc.).

Anywho, as I say to mm, keep up the damn fine work!

 

[mm1352000]

Some info from the PBDA specs that might be of interest:

· The following are the requirements for WMC trick modes:

· FF1:3x (30-second commercial in 10 seconds)

· FF2:10x (30-second commercial in 3 seconds)

· FF3: 100x (30-minute show in 18 seconds)

· RW1: 3x

· RW2:10x

· RW3: 100x

· Forward Slow motion: 0.5x

· Reverse Slow motion: 0.5x

· Forward Frame Skip: 1-frame stepping always

· Reverse Frame Skip: 0.5s – 1 frame

· For Windows Media Center, smooth full-frame trick play is used for 3x fast forward for Standard Definition (SD) H.264, 6x for SD MPEG-2 video, and 3x for High-Definition (HD) MPEG-2 video.

 

[Benoire]

How does this compare to what MP currently does?

 

[mm1352000]

How does this compare to what MP currently does?

No idea - sorry.
Just happened to be looking through PBDA specs for other reasons, noticed this, and thought it might be relevant. It could be totally irrelevant.