| Author | Message | ||
     Giorgio Bogoni Rating: N/A |
I'm thinking about playback issues playing a side-by-side video in extended-desktop mode on a dual-head graphic board connected with two polarized projectors. I think we have at least two things to consider: 1. We need a playback application that, turned to full-screen, uses the extended desktop (let's say a 1600 x 600 pixels) 2. We need a way to play all 1600x600-frames at an high refresh rate (at least 24 fps) - I expect CPU and GPU overloading and a lot of skipped frames (check statistics in MediaPlayer) This is what follows: 1. We can try MediaPlayer and QT, any other suggestion? 2. Well, when I use a DVD-player on my PC it seems to run smoothly but when I play a large size AVI a lot of frames are skipped. This means that the bandwitch isn't the bottleneck (HD access is faster than DVD-drive one) but there's some CPU or GPU overloading. I think there should be some HW support for MPEG2-decoding in VOB files on the DVD. Fine! Can I use this HW support for general MPEG2 AVI decoding on my HD? And if this support can be used only by the DVD-player application, can I encode my AVI to a VOB file on my HD (without burning a DVD) and running the DVD-player on the extended desktop? Will the DVD-player support the extended desktop? Should be possible to encode to VOB format a not-standard aspect ratio AVI (like my side-by-side will be)? Or, maybe, can I loss half the horizontal resolution and compress my side-by-side into a "compressed side-by-side" to fit standard aspect ratio for VOB files? (playing it back at full 1600x600 resolution it will turns to a "side-by-side" with some quality-loss). Any suggestion? Comments? Giorgio. | ||
| M.H. Rating: N/A |
Giorgio: We can not use the HW mpeg2 acceleration cards becouse they support only some fixed format output + the companys does not support Microsoft Direct Show standards witch gives acces to the device ( I have discused it with SigmDesign technics) .. The solutions are: 1) use low compression algoritm for storage, the bottleneck will be the disc acces in this case 2) use 2 synchronized computers, each plaing one eye view. Practical testings made by my friend Paul Bourke show that it is the best solution. They use this setup for astronomic 3D movie projection in 2x1024x768 res ... They have succesfuly tested passive method, witch gives for well tuned setup better results than active ... Transfer from VOB to other format is possible, but I have to find some method witch could be for more easy use than the one used by me ... The best technology with I have now is: Transfer to above/below ... Encode by DIVIX4 ... Play by my next generation OpenGl/Direcct Show HW acclerated movie player (I hope make public soon, it is in aplha testing stage + gui design) ... Redirect the HW page flipped output to 2 outputs by the graphic card setup ... | ||
| Giorgio Bogoni Rating: N/A |
Thank Michal, I'm waiting for your next generation movie player but redirecting the page-flipping signal to 2 output it's always quite difficult (we need to crack a dual-head GeForce board to Quadro in a WIN2000 enviroment ....). I've been thinking about the sync computers ... how can it be done? Do you think that 2 identical PC will play the video in sync without HW-sync (just connecting them to one keyboard when I press "PLAY")? I doubtfull ... Giorgio. | ||
| M.H. Rating: N/A |
Gorgio: Yes, my player will require hacking the GeForce drivers using Riva tuner ... But it is nothing diffcult, working excelent for NT4,w2k and Win XP on any nvida GeForce model ... Realy great of GeForce 3 ... Paul Bourke use synchronization based on TCP/IP comunication between the machines ... Anybody having experiences with Direct Play (network based game sync api) could easy modify sample movie players witch are a part of Microsoft Platform SDK to achive synchronous movie playback. The codes in the MS Platform SDK conatins examples of both universal synchronization server based on Direct Play (serial port or any network connection between the machines) + very simple movie players ... The same thing could be done more difficul by using the internet socets ... Precision at level 1/30 sec is sufficient ... Maybe that I will sometimes encode this thing, but there is to low public interest in such code ... | ||
| Giorgio Bogoni Rating: N/A |
Michal, as far as I know there's no dual-head graphic board featuring GeForce3; do you think that your player could stand 2x1024x768 DIVX4 decompression without skipping frames? Anyway it's sub-optimal because, genarating two 1024x768 images from a single 1024x768 above-below image, it has to interpolate missing lines and - working in real time - it hasn't enought time to use an efficient interpolation alghoritm. Of course this is the easier and cheapest way: 1 PC, no sync trobles, 1 movie to manage ... do you think that using the best interpolation alghoritm in batch mode (Photoshop) on every single frame (TGA image) would gives really best results or not? Thanks again, Giorgio. | ||
| M.H. Rating: N/A |
Gorgio: The botlneck is the speed of video decompression, with is determined by the CPU performance. The graphic card HW is used for the filtered image zooming only (the interpolation algoritm is HW accelerated = no influence on speed, optional linear or trilinear filtering). Hi quality filtered zooming on the fly is no problem. The speed was almost the same of all GeForce models, the key was the CPU. We can play without frame skiping 800x600 movie at 30 fps in above below format HW zoomed and filtered to 800x600 full screen frames( Divx4, P III at 1G). | ||
| M.H. Rating: N/A |
Gorgio: If you are interested in the principe - have a look on the demo code (executable demo available for download) on this WWW: http://www.gamedev.net/hosted/nehe/tutorials/lesson36.asp This demo demonstrate in praxis what horrible trick could be done with video on the fly by the help of HW accleration ... The technology with I use is based on DirectShow instead of the Video for Windows used in this demo code (it means compatible with more video formats + about 3 times faster + full audio support) ... | ||
| Giorgio Bogoni Rating: N/A |
I'll check the demo as soon as possible. Do you think that, buying a P4 1.7 with a dual-head GeForce 2, I'll be able to run a 2 x 1024 x 768 @ 20 fps from a DIVX compressed above-below 1024 x 768 (with no horizontal black lines in the middle) with high quality missing lines interpolation? As far as I have understood it should be possible .. Giorgio. | ||
| M.H. Rating: N/A |
Giorgio: I have PIII at 1G as the best machine for testing ... You can try the speed of 1024x768 DIVIX on something, my player will require aprox 30% aditional power ... | ||
| M.H. Rating: N/A |
Giorgio: I have PIII at 1G as the best machine for testing ... You can try the speed of 1024x768 DIVIX on something, my player will require aprox 30% aditional power ... | ||
| Giorgio Bogoni Rating: N/A |
Michal, I'm planning a small 3D theatre and I'm considering a lot of things (not only technical ones). I think your solution is the best one at the moment but I don't own a fast PC for testing right now. When do you think you'll public your new player? Regards, Giorgio. | ||
| M.H. Rating: N/A |
Giorgio: I am not sure if you will need it, full double screen playback in dual monitor setup (desktop in left right or above/below setting) by normal windows Media Player from left right or pure above/below coded movie shuld give identical results , if you need 2 chanel output. I am more focused on the single moinitor HW page flipping ... Making the player public depends a bit on the VirtualTV company for witch I am working now on stereo-video problematic. I am forced to ask them for permission ... |
