smooth and jitter free video playback

[nw42]

Hi!

I want to solve some problems that result in unshmooth videoplayback and jitter. No hardly stuttering video - only slightly really hardly noticable jitter that appears after seconds of smooth playback.

--> No problem if I show the video on a 19" Computer Screen - but if I use a beamer the jitter becomes a problem.

--> How to see the jitter? There are some situations realy sensitive for jitter:

- fast but uniform paning cameras (a church dome, paning up a building front - fast paning into pictures and documents like offen seen in documentary...)

At first: No, I don't have a slow old machine and wonder wy my 1080p video is stuttering - and NO I don't have the well known audio sync problems. And Yes the problem I'm speaking about is affecting all video players and different computer systems.

I tryed to analyze what could be the cause of this:

01) CPU
The problem occurs even if I try to playback an unc. AVI 320x240 on a Core2Duo 2.66GHz - it's not CPU dependent.

02) Encoding
The Problem occurs even on commercial standard DVD's and unc. small test AVI's without audio.


03) Audio Sync
I had read a lot of these audio sync problems - to be sure I had tested different sound cards like the Terratec AUREON with adjustable buffer - no change - switched the VLC audio off and used video without audio - no change...

04) Display Frame Rate
Something I hadn't found much information about was the display frame rate - if the display refresh don't match the video frame rate (or a multiple of it) the video is jittering by force because the player can't resynthesize the needed video frames for the display timing.
This is the only point that made any difference to my video playback - with 50Hz disply refresh rate a PAL video played much smoother than with 60Hz default display refresh. (another point is that most modern 24" TFT's don't support 1920x1080@50Hz via DVI/HDMI - unusable for PAL playback! - Any suggestions for an affordable 1080p PAL video control monitor?)

05) Bios Settings - Overal System Tuning
I'd checked all the settings - changed timing settings - but it hadn't any affect at all.


--> As I realized even RAM Player showed jitter with 30fps footage on a 60Hz display... what is going on here??? It has to be possible to draw an image every 16,6ms to the screen...

Any good hints for me?

Best regards

Danko

[DJ]

Try looking a ReClock on the web. This offers some reasonable explanations as to the problems of using a computer versus dedicated hardware.

[nw42]

Hi DJ!

Thanks you for your response. I read your posting viewtopic.php?t=26942&start=0&sid=c6962 ... 6cd55c5e7e
here.

I think I understand the problem in general but wondering that nobody out there seems to notice it.

If I compare VLC 0.8.5 to MS MediaPlayer 10 with Nvidia PureVideo there is a huge difference - MediaPlayer is nearly perfect in playback especially with interlaced content (thanks to motio adaptive deinterlacing via DXVA).
But from time to time even MediaPlayer don't get it right and slightly jitter appeares.

VLC shows a more unprecise playback - obvious in fast paning scenes.

Now I have to decide for future use - can I get a "perfect" playback experience with VLC? Are these timing and genlock problems addressed in VLC 0.9 dev? You say it's complicated but possible to use Reclock with VLC - if so - resolves this all problems?

Some more questions I'm telling me (and you

--> How is the MS Media Center Platform dealing with this? I read that MediaCenter always use DXVA and the VMR9 to geht smooth playback.

To test playback We'd connected a fast WinXP Pro machine with Mediaplayer 10 + PureVideo to a Di-Ventix HD mixer via DVI. Before playing we adjusted the graphics card to exact 50Hz for our interlaced PAL video.
The result was monitored behind the Di-Ventix mixer on a multisync. CRT.
Di-Ventix and control CRT were operating even with 50Hz.
The playback was ok - no noticable jitter - but after some minutes genlock problems betwen the PC and the video mixer occured and the video was stottering in a stange way that indicated that input timing via DVI and output timing via SDI had some genlock problems.

The only thing that worked without problems was to output the video via a Blackmagic SDI board. Perfect Playback for hours... And I'm wondering again, because we had to route the audio to the internal onboard Intel sound chip (we could'nd use the audio via SDI) - but no problems with sync... hmm

Is it so hard to write 25 video frames to a 50Hz Framebuffer?

I'll try now to use Resync. Thought it would not run with VLC and don't really want to use another player than VLC because I find VLC is the most expandable platform and we already use VLC for other application...

Best regards

Danko

[DJ]

I don't recommend ReClock. Getting it to work with VLC is a bit like standing on your head while touching both feet with your hands and spinning. It has been awhile since looking at the program though.

I mention it for reference. The problem is to many clocks in a computer, thermal drift in the clocks, refresh rate of the video, and the inability to use PLLs in a computer that would lock all the clocks together. Some seem to believe that a replacement for the renderers in DirectX would help solve the problems. In most cases the sound card plays the most important part here. All digital video is sync to audio.

Is far as people noticing this, it depends on the nature of the jitter. A good system should only show jitter in slow horizontal pans which is dependent more on the speed of the pan and the framerate of the film. Try going to a Movie Theater again and pay attention. Most professionals try to avoid the problem where possible, but if it is a choice between creativity (a great scene that would be very difficult to do again without adding huge expense) and technology, creativity usually wins. Add in the inherent problem with computers (mentioned earlier) and the problem becomes accentuated.

As far as what some of the video card Manufactures are offering for HD support, this is a Direct Show filter to add hardware support for h.264. I don't know if they are providing a new DirectX renderer or how or if this shows improvement to the jitter problem in other formats. What I do know is that at the moment VLC can't use these. But there are discussions for future releases. Also at the moment there is no real standard interface for these and nothing in the open source community to draw on.

[nw42]

Hi DJ!

I use PC based playout for small film festivals for years and as along as I had to compete with unstable DVD playback from DVD-R with menu overlay on screen everything was ok.

But now things changed a bit. e-cinema stands in the center of interest - nobody can afford to eqip all festival screens with highly expensive DigiBeta + HDCam tape recorder + HD video mixing devices. So they look to us crazy "highdefinition PC guys" and say: "Hmm - but there is some jitter that i don't have seen on the HDCam tape..."

Unfortunately I have to screen a lot of documentary stuff - and the producers say: "Ok this is an interlaced production made for TV not for cinema" and they have all this sensitive horizontal fast pans over pictures and documents every few seconds...

Ok the demandings to this affordable PC based e-cinema equipment is huge - but hey! - this *** powerful Gefore 7900GTX can render gigaflops of floating point operations per second to show ultra smooth virtual 3D worlds with 160fps - but is stuttering with a simple 320x240@25fps computer video???? I can't accept this as the final anwer!

On the other side there are a lot of video boards out there for video production - showing that is is possible to playout jitter free video with a PC even if it has to sync. on the internal sound card (Blackmagic + Intel onbord sound)

As far as I understand we don't have a bandwith or processing speed problem - we "only" have to sync the playback - reclock shows how to start...

In the last two years I had to do a lot of different things and don't watched so closely to the dev. of video player software - now I thought ok, lets use some of these cool software players running on a fast machine - change the user interface for prof. operating and you will get a cool playback solution...

I supposed to get a lot of problems on my way to a cool e-cinema server but I never thought that not even a simple play would play a video but only showing jitter instead - first round goes to murphy - pling

Current Situation is:

01. Blackmagic SDI Board works fine (But SDI isn't my future favorite for upcoming 4K cinema resolution)

02. Windows Media Player + NVidia PureVideo Decoder shows perfect deinterlacing + minimal jitter (but even has to be improved - another thing is that the PureVideo decoder doesn't support extended Profiles like 4:2:2 MPEG II or 100MBit data rate)

03. VLC shows unacceptable jitter and has problems with deinterlacing -> it has to be activated manualy, hard to deal with in a play list - and it doesn't deinterace HD material...

hmm - I relay would like to use VLC as base for e-cinema plyback but currently it seems to be impossible to play a jitter free movie...

Anybody out there interested in helping me to solve this? I'm a 3D animator and post production specialist having expertise in creating profesional user interfaces and setting up powerful hardware systems - but I'm not a coder...

Best Regards

Danko

[DJ]

I have been a consultant for new product for many manufactures and have helped build many Production and Post Production houses round the world. I can empathize fully with the issues here. Specially when dealing with a client. There are varied problems associated with the issue.

1. For the most part the consumer is not demanding that the issue is resolved. Most of them are content that the file plays and can be streamed through the house or received round the world. Given the current state of the average ADSL service this is a feat in of itself and says nothing about quality of the material. I generally stay away from answering many questions regarding streaming on this forum because of this.

2. The biggest problem at the moment is audio card manufactures. Used to be both audio and video card manufactures. So there is some progress.

3. Microsoft need a new audio renderer and ReClock rather proves this.

4. Presently there are 4 or so levels of sync that go from no sync to soft sync to normal sync to forced sync. VLC I believe uses normal sync because of it's streaming capabilities and the fact that it is a packet based player. Try looking a MPlayer, as I remember the default is no sync with a soft sync option. But while this is the smoothest player I have come across, if the timing in the encoding is not correct the player will not sync.

5. Another anomaly is more novas user related. In that a user will rip a movie and there is a delay that is between .5 and .7 seconds off true sync because they don't know what they are doing. Then comes the grand attempt to correct this. Unfortunately in most cases even though they have spent hours trying to get close to lip sync there is a drift that makes this impossible for most players and depending on the format some players even refuse to play the file. For a player that does not sync the drift is most noticeable. Then this or other users trying to play these files complain that it isn't right and the player is the problem because such and such player plays it OK! When in fact it is not OK! But in fact shows gross errors.

6. The most progress has been for the professional in dedicated equipment using special drivers for multi monitors (this can also be a big headache for a Windows environment) and in some cases special renderers. With these a no sync or soft sync can be used without problems because these people are supposed to know what they are doing. Therefore a good audio card that supports the desired formats is all that is required. But all this is for the editor and client so that they know for sure the problems that may ensue is the equipment the user chooses to play the end product on and not a problem with the product.

7. Most dedicated hardware employ 1 crystal, divide by and PLLs to keep everything in perfect sync without adding additional jitter to the product. Unfortunately this is not possible with the current state of computer technology for the average user. We would all like to believe this will improve as HD product and large screens fill livingrooms round the world. I would expect the average consumer to become more aware of the issues at hand and that companies like AMD, IBM, Intel and or Microsoft will offer better solutions. But at present they ar moving toward dual core processing that shows NO improvement whatsoever in these areas. In fact in most cases thus far it seems to be causing new issues in timing.

[nw42]

Hi DJ!

My hardest problem is that I dont have do dev. a commercial project - in this case I'd decided to build all from scatch to meet the high demandings

ZoomPlayer + Reclock showed how it could work. But it's a complicated unstable setup - hard to create a defined environment - too much different programs and options.

In addition ZommPlayer nor Recklock are open source and arn't a good base for future work.

You sad some thing about special drivers and renderers - any suggestion for the "semipro way" - I can't afford the bluefish 4:4:4 2K DualLink SDI board with included player software for about $20K...

What about the ATI AllInWonder boards - they have at least integrated audio/video processing?

Another board I thinking about is teh Blackmagic HDMI board - but to play interlaced HD content I need a good deinterlacer/scaler - to expensive if externaly applied - hmm - from this point of view only a pc graphics board remain.

Another hard thing is to find Displays and Beamer with adequate timings on it's inputs - the good old multisync CRT's are working fine but most modern 24" TFT's only accept 60Hz at the DVI inputs...

hmm - hmm - hmm - have to speak with some guys to make a decision on how to continue to work...

Best Regards for your comments DJ!

Danko

[DJ]

http://www.videoguys.com/

[nw42]

thank you DJ!

Danko

[nw42]

Hi DJ!

Do You have an idea whats about multible video outs on multible monitors if it comes to sync?

For playback it would be useful to have one control display with interface and a small video preview and on FullHD video out on secondary display.

If I have to switch framerate for the secondary display to match media framerate - whats about my primary??

In the case of display mode change I lose control for a second and if something goes wrong my primary display is dead and I have to reboot - bad option.

On the other side a video preview with jitter doesn't help to say if the main output works fine (normally I don't have a good view to the big screen from the playout operators position)

So would you agree that control + main output display have to support all used media refresh rates natively and they both have to be adjusted before playback starts?

The more complex way would to use a HD DVI splitter to connect a 1080p control monitor - but I have to find a small 1080p 24/50/59.94/60fps Device... we had used Samsung 24" TFT's but they don't accept 50Hz via DVI)

Best Regards

Danko

ps: had a look to the ATI AllInWonder with integrated sound - hmm - havn't seen a secondary display connector and the audio connectors don't look very tough...

[DGMurdockIII]

bump

[arteo]

Hi,

I wil try to playout MXF file with vlc to decklink
can you tell me please if i need to configure anything in VLC

Regards

[DJ]

So would you agree that control + main output display have to support all used media refresh rates natively and they both have to be adjusted before playback starts?

Yes! But this shouldn't be a big issue to satisfy a client when you will be spending hours in editing with him.