A guide to stutter free playback with Reclock

[ErikLarsson]

Hello,

I've been struggling with stuttering playback for years now, and struggling with reclock aswell. There has always been issues with it and it never worked 100%.

I've written this post because i've finally solved all my issues, and can enjoy 100% stutter free playback of both DVDs and h264/x264 content.

What is reclock?
Reclock is a audio renderer and it solves the problem with stuttering playback because it matches the speed of your video to the output HZ of your monitor/tv. Many TVs also lack the support for 24p, making content with speed 23.976 a pain to watch (almost all movies, TV series and NTSC DVDs). Reclock speeds up the playback of this content (to 24fps or 25fps depending on your TVs capability) and adjusts the sound accordingly. If you don't want the pitch to go up (chipmunk effect) there is options to pitch correct it aswell. Works like a charm for me!
Reclock version 1.6 have a manual which i suggest you read, very helpful.

What problems have I had?
I've had stuttering playback in many forms. Sometimes, it goes well for a while, then stuttering begins and never stops. Or stuttering is there from the start and the only solution is to pause and play again. Or sound and video get out of sync. These problems have been going on for years, with different TVs, hardware (2 completely separate HTPC setups) and software. Reclock have solved all of these issues for me.

What solutions have I tried?
I've basically tried different players, codecs, hardware, filters, renderers, OS's and alot of configuration. Nothing would suffice.

What is smooth stutter free video?
For me it is when each and every frame of the content is being rendered perfectly in time. It also means that there is no frame that is being displayed twice, or thrown away. A camera panning should be a smooth motion, without any hint of stutter och hickup, or even unsmooth motion. To show 24p content on 50hz TV without reclock makes this impossible.

What settings is working for me now?
Right now, im using Reclock 1.8.x and Mediaportal 1.0 RC2.

• Nvidia VSYNC is set to Let application decide.
• Reclock is set to DirectDraw. (Direct3d gives error message when exclusive mode is on, which i need to stop tearing)
• Reclock VSYNC On for all content (Yes for VMR9)! (see explanation below)
• DirectX Exclusive Mode On (to stop tearing for me)

Why do VSYNC solves alot of problems?
VSYNC seems to be very important because without it playback that starts at the wrong time will stutter and never break free from it. The VSYNC signal will be at different places every time you start playback and if you are unlucky you'll get stutters. For me, it was about 1/3rd of the times i started/resumed playback. Only solution was to pause and play again. And even when the movied played OK it would drift into this state again. Very annoying.

How to adjust VSYNC?
There is a good explanation for this in the Reclock 1.6 readme, but following the instructions there did not solve my problems. Here's how i got it to work.
Start Mediaportal, start a movie. Press Shift+Ctrl+Alt+F9 and F10. This will show VSYNC onscreen and a tearing test (which is good to observe if you are looking for stutters).
The VSYNC indicator consists of a small horizontal line moving up and down, and small dots forming a vertical line. These will eventually form a small cross after a while. (If nothing is showed when pressing f9, check reclock for error, probably you need to disable DXVA).

To find your jerky spot, switch VSYNC OFF (for the moment)
Every time i unpause, the cross will end up in a different spot. For me, if the cross ends up close to the top of the screen, i get jerky playback, forever. Because vsync correction is off, the cross will not move at all.
So i pause and unpause, and if the cross ends up somewhere on the bottom half, i get smooth playback. Now i've confirmed that my jerky spot is close to the top. This will be different for everyone.

Now, below the setting for VSYNC in Reclock there is a slider. This slider will force the cross to a certain spot. And because i know that the top gives me jerky playback i adjust the slider so the mark is as far from it as possible (including wrapping).
|--V--------------------X-------------|
The V marks where my VSYNC gives me jerky playback (as in: start of slider = top of screen, end of slider = bottom of screen).
The X marks where i put my VSYNC correction slider. Of course now VSYNC must be switched on again.

Now, if i start the same content again and pause and unpause until the cross is at the top (which gives me jerky playback, remember) observe the magic! The cross moves! ^^
The cross will slowly crawl into the preset area (marked by two small dots left of the cross). And it's evident that if my cross starts out at the top after unpause, i can see small jerks for less then a second, and after that the cross has begun to crawl towards the marking, and video becomes smooth. And it never leaves the marking!! Heavens!

So no DXVA?
For me, i had to disable DXVA (in Mediaportal options) or VSYNC would not be available for DVDs. CPU increased from ~30% to ~40%, but it is well worth it for me.

But sometimes my CPU can't handle the content, will it play on perfect after the hard part?
Observe the VSYNC cross. If playback is good, the small dots forming a vertical line will be close, forming a solid cross. This is likely to give you good playback. On some videos where my CPU is not enough (or if i postprocess too much) the small white dots will start to scatter to a much wider area (vertical that is). But as soon as the hard part is over, the dots will appear close again and the video will be smooth. No need to pause and unpause. I think the same applies if there is errors in the content etc, so no more holding your HTPC's hand, it'll pick up by itself.



Im not an expert, i just have years of struggling with this and a very sensitive eye for jerky video. Please feel free to correct me where im wrong and provide even more information to this thread so we all can get absolute stutter free playback in mediaportal!

Thanks for a great software Mediaportal team!
/Erik Larsson

MediaPortal Version: 1.0 RC2
MediaPortal Skin: BlueTwo
Windows Version: WinXP Media Center Edition
CPU Type: Amd 2800+
HDD: 120gb seagate IDE
Memory: 2gb ram
Motherboard: Asus A7N8X
Video Card: Geforce 6800
Powerstrip: No
Video Card Driver: 177.66
MPEG2 Video Codec: Nvidia purevideo
MPEG2 Audio Codec: ffdshow
DivX / Xvid codex:: ffdshow
x264 codex:: CoreAVC
Audio renderer: Reclock
Remote: MS MCE remote
TV: Sony KDF-e2010 50" RPTV
TV - HTPC Connection: DVI - > HDMI
VRM9 Exclusive mode:: Yes
VMR9 VSYNC: YES!

[Seeco]

This sounds really promising, although I would like to get a more thorough understanding of what the whole process actually does. For example, what exactly does it mean that this "cross" is situated in a particular vertical area of the screen? And what is it that you really are doing by adjusting the vsync slider in Reclock? How did you come up with the precise place to put the slider, did you go by any special markers or is it not a matter of precision?

It is really neat to be able to use the horisontally travelling vertical line to check for motion smoothness, thanks for the tip. The thing is though, when I display the line it isn't really solid as it travels across the screen. The movement seems fairly smooth, but the line itself looks as if it has another line just like it lagging behind. The "behind" line flickers, but it doesn't really look like ghosting (i.e. it's not a matter of a gradually fading "ghost" behind the real line). I notice this in regular video as well, where for example contours of dark objects against bright backgrounds will appear to flicker and display a "false contour" a bit away from the real one, as the image pans. Is there a word for this particular kind of artifacts? I will try to describe it better if no one recognizes what I'm talking about

[ErikLarsson]

If you'd like to get a better understanding, read the manual in Reclock 1.6 release. But if you plan on using it, download 1.8.x version!
Old Reclock 1.6 site
Reclock 1.6 download

In my understanding, when i start playing a video the horizontal line ends up where my VSYNC pulse is detected, and each dot represents a frame rendered. The position of the line and dots (from top to bottom) indicate when it happens (measured in time).

So when i play video and accidentally start the first frame in bad sync with the VSYNC pulse, it'll struggle and switch between trying to render the frame and wait for the next pulse.

I'll post some images explaining this better but read the section in the manual.


Regarding your ghosting, is the bar broken in any way?
It sounds like your TV is producing the artifacts, other than slow response time of pixels i have no idea what could cause that

[Seeco]

Thanks for the explanation, I'll read through the manual and see if it becomes any clearer. Have you been able to draw any conclusions about what the actual effect is of placing the vsync slider in different positions? I'm currently using the latest beta of Reclock I could find, so that should be all right. Again, did you go by feel when deciding where to put the slider or did you have some exact reference?

The horisontally travelling tearing check line is not broken (as it would have been if I had tearing). I also know that this artifact is not due to my TV. First of all interlaced TV broadcasts which are deinterlaced with hardware (I use a FloppyDTV card and PowerDVD with hardware deinterlacing) show perfect motion handling. Displayed objects in panning shots look sharp throughout the motion, with no strange artifacts whatsoever. Also my TV is fairly top of the line (Pioneer PDP-5080) and if this was supposed to be the standard for motion handling with 24p material I believe that people would have reacted. When I've been fiddling with different codec, graphics and renderer settings I have also sometimes succeeded in making the problem less evident. A couple of times I have noticed that motion suddenly seems a lot more fluid in h.264 material, but I have never been able to pinpoint the cause for this. I sometimes also get the feeling that the problem is more evident in some videos than in others.

[ErikLarsson]

Well to answer your question about the slider.

I reproduce the stuttering by pausing and playing over and over, and once i found constant stutter, i observe where the cross are. (this will be different for all machines). Once i know where this stuttering is, i can place the slider so the cross will always be as far from the stuttering place as possible.

[red5goahead]

Seems not work under Vista and Evr





the VSYNCH indicator is on the top and the slider position of reclock setup is not used.
VSYNCH seems not work with mp and its custom evr.

[ErikLarsson]

Originally Posted by pepreal

hi,
the guide you made was quite helpful, but got a question, when you change the bar for the vsync the bar with the little dots that going around a little bit, has to be between the to horizontal bars right? because when i do that and unpause it it will be there for a couple of seconds and then goes back to the original position in uper conner.

is that normal?

thanks for the help

Greetz, pepreal

Basically, it seems that you've switched on VSYNC correction, and at the moment you unpause the frames are rendered pretty scattered compared to the vsync horizontal line (small white dots cover almost half of screen height or something) but it calms down creating the cross. Also i interpret that this cross then moves slowly to the top of your screen. This is all good behavior!

Seems like you've set your VSYNC bar far to the left.
Far left = top of screen
Middle = middle of screen
Far right = bottom of screen

The question is, do you get jerky playback doing this?

What you need to do is to find the spot that gives you jerky playback. This must be done with VSYNC correction OFF! When VSYNC correction is off, the cross will end up at different places every time, and never crawl. Pause and play until you get jerky playback, and take note where the cross is. Confirm by pausing and unpause alot until you can confirm that positions away from the jerky spot gives smooth playback, and positions close to the jerky spot always is jerky. Once you find this spot, switch on VSYNC correction and move the slider away from the jerky spot. Now, the cross might end up in the jerky spot once you unpause, but it will crawl away from it!

This will be different for everyone, but my jerky spot is at the top, and therefore my slider is like this |---------------X----|

Originally Posted by red5goahead

Seems not work under Vista and Evr

Actually, that picture of the cross is not indicating anything bad as far as i can see. I'll post some screenshots of how mine looks later.

[Pepreal]

My bar is between the middle and bottom of the screen and thats to position that i get the best moving tearing bar, but sometimes is will jerk and the next time is will move smooth, i have some trouble to get it perfect

btw i dont no this but the cable that i have is vga to scart rgb and i dont have a hsync or vsync only a composite sync, does that mean that i cannot get a smooth tearing bar al the time?

-----

when is use the 1.8 my S/PDIF doesn't work anymore with 1.7 beta is works perfectly or do i have to use a special option

--------

why does this test for me only works in direct3d if i use directdraw reclock can not find my refredh rate

[ErikLarsson]

Ok first turn VSync off.
Pause and play until you find jerky spot. Note where the cross is located.
Turn Vsync On.
Set the slider so that the cross will be as far away from the jerky spot as possible.
Confirm by pause and playing and notice that wherever the cross starts, it moves away from the jerky spot.


For your spdif issues and directdraw issues i have no idea, sorry.

[Pepreal]

oke is much better now but what postion i take its stil a little bit jerky on time and the other time its smooth

i think i has to do that i dont have a vsync

for people that are interesting this is the cable i have VGA to RGB SCART Direct Drive with ATi Radeon


found btw a nother way for x264 with fps 23,97, in haali you can set force fake 25 fps then reclock see that the movie is running on 25fps for me this works i can see that it is running a lot smoother than when i set this option off in haali