So here is some info that should be useful if you are creating or thinking about creating video games…

Action games are coming into fashion again. Game consoles have their download services where action games are the top sellers and the new mobile devices like iPhone and Android have opened up a whole new market for small and quick action games.

In action games you need your game to respond to input as quick as possible. This is Key!

Creating a fast responding action game can be a real challenge, and knowing just how long latency your game has isn’t trivial, even if you created it.

For this discussion I’ll use the term latency for the time between when you press the fire button in a game to when you see your player actually firing in the game.

Latency, or network latency, is often used for network game and there you see extra latency caused by your connection to other players over internet. Let’s just save that whole discussion for another day.

When something happens on your computer screen it takes a few mili-seconds before you will react and press a button in response on your game control. This time is up to your reaction time, this is the time that you as a player has control over.

So what happens when a button is pressed? The game will need to read the input, feed that input into the game and do some calculation as to what should happen as a result of that button press. This whole sequence is called the games update loop. The player has no control over this time, its up to you as a game developer to make this time as short as possible.

The game then needs to render to the screen, the graphic card needs to output it to the display. Let’s call this the render update. This can also take more than one frame depending on your games rendering architecture.

Finally the monitor needs to show the graphics on screen. Ideally you want this to happen as quickly as possible. This part is up to the hardware vendor but as a game developer or a gamer you should be aware.

Your monitor has a response time and this is the time it takes for something to appear on the screen. Some monitors, made for watching television, will apply filters to make the picture look better. These filters are applied over several frames ie output is delayed and all games will have longer latency. For the best gaming experience you want a monitor with a small response time and no filtering or filter’s you can turn off.

As a game developer you need to focus on the game update and rendering loop.

To measure how many frames latency your game has get a video camera that is capable of capturing at 60 fps. Film the game screen with you holding the control in front of the screen. Record as you click the button, preferable with some debug rendering enabled so that you render something on screen that you can not miss and that you can compare with something in the actual game.

If you do not want to buy a fast video camera you can do a poor mans version. Write bytes straight to the front buffer memory at the same time as you read the input device. Then just record a video screen capture. The written bytes will appear as flicker on the screen but that is all you really need. This approach will work on consoles but on some platforms you simply don’t have that low level access to the front buffer.

Use video capture software like Fast video indexer to extract frame by frame from when you click the button to when you see the result. Count the number of frames and there is your games latency in 60 fps frames ie 16,67 ms frames.

Here are some general tips for improving your games latency.

Peek input buffers as close to their use as possible. If your game uses DirectInput, xinput or any other buffered input device, try to read the input buffer as close to where the data is used as possible.

Many game loops start reading the input at the beginning of the frame independent of the game state as reading devices is game state independent. If your loop does anything between input update and input response, key presses during that time will have one frame of extra delay.

Run at as high fps as possible. If you can run your game at 60 fps instead of 30 fps the latency will be mush lower. If your game is GPU bound you still want your game loop running quicker. Consider separating the rendering and update loop.

Don’t introduce extra frame latency. This might seem obvious, but it is quite easy to introduce frames of latency when optimizing for parallelism, blending animations, etc Analyze the flow from an input point of view and verify your result with screen captures.

Low input latency can be the difference between a fun or a frustrating game experience, don’t forget or ignore it.

First of all people people are complaining about the user interface so it needs improvements. My idea at this point is to rewrite the user interface in c# and WPF but still use the tested video index engine that is written in c++. I will continue to use direct show for video frame extraction as it is the video api that has support for most video formats.

The other big problem i have is with crashing/buggy codecs that is causing the program to crash. To solve this I intend to launch the indexing of each video in its separate process, if that crashes at least it minimizes the risk of crashing indexing of other videos in a batch.

If you have ideas of what you would like to see in a new version of Fast video indexer please let me know either by posting here or by mailing me.

If you are on my Fast video indexer list should already have gotten the link but if you are not, here it is:

Solve video problems

Download and print or save it for later. Feel free to share the document as you want, link to it, mail it to your list or host it on your site.

I would love to hear your feedback and ideas for improvements on the document

Lets start with the technical bit and and the end of the text I will give you a practical tip on how you can solve your codec issues the easy way.

Windows has a really awesome, but at the same time, very complicated system for programming videos applications, called direct show.

There are other alternative programming interfaces but if you want the best of features and speed you need to go the direct show way. That is what Fast video indexer and Windows medial player uses.

Direct show allow an application to create a graph that the video file data flows through. Each node in the graph is called a filer. A simple graph would have a filter to read the input data from the video file. That filter would pass on the data to a filter that splits the stream into a video stream and an audio stream, the video stream would go into a decoder filter (a codec) and finally the decoded video stream would go to a render filter to display it on screen.

The type of graph needed depends on the type of video file and the content in that video file.  So for each file you watch this graph has to be created and the application needs to figure out what filters to create and how to connect them.  To futher complicate things each of the filters are run as an independent thread, this is really good performance wise since we can make use of more than one cpu core. But, it also makes writing the filters correctly much harder. Filters that may appear to be correct can infact have timing bugs that only appear on some computers with some configurations.

When fast video indexer crashes, 9 our of 10 times it is because the video uses one or another codec that has a bug in it.

If you have a huge batch of videos that all require different types of codecs you are really running a huge amount of code and a bug in any of it can cause the program to crash right away or to cause problems with videos later in the queue.  If Fast video indexer crashes when you are capturing it will try to pick up from the place where it crashed when you restart it. If the crash doesn’t happend again the problem was most likely with one of the videos that was captured earlier, just that the problem did not show up right away.

So what can you do to reduce codec problems?

Professional users should decide on one (or at least a limited number of) tried codecs and stick to that one. In that way you reduce the problem significantly and you will very very seldom see crashes.

If you are having problems from time to time start by Downloading the codec tweak tool and run it on your computer. This tool will go through your computer and find registry entries that are broken, codecs that have known issues and:

• Scan the registry to detect and remove broken references to codecs and filters.
• Generate a detailed log of all installed codecs and filters.
• Enable/disable more than 200 codecs and filters (if they are installed).

If you need many different codecs on your computer consider the latest version of the k-lite codec pack

Anyway here are the start of the new Fast video indexer award page. I just added the last couple of awards to it but now at least i have a place to add them as they arrive.

The last year I have been focusing on other projects than Fast video indexer. I am working in the computer game industry and this year I have spend a huge amount of time working on two big games that are now out in the shops. If you are interested feel free to check them out, Just Cause 2 and the pc version of Battlefield : Bad Company 2.

Anyways, the next couple of months I will try to focus more on Fast Video Indexer. First of all I will spend some time improving this neglected web page and this blog in particular. I have already started a bit updating the FAQ page and a picture of me on the support page.

As for the software the last years and a half’s updates have only been small fixes to problems. I do think the quality of the program has been improved alot but really you have not seen any new features. Right now I am planning on where to take the software and I would love to have your feedback. I would love to know more about how you use the software and what you think can be improved.

Donald White, recently wrote and told me that Fast video indexer had problems capturing all frames from some of his video clips. Donald uses the program to capture videos of dancers to help them improve their act. He did send me a video that had the problem and I was able to reproduce the results. Seems that I had a round off error that could cause frames to be skipped. If you use fast video indexer to capture every single frame as an image you probably want to get this update.

I am currently working on another minor update to the software. actually I had forgot I even had this blog. Now Ill keep you updated here a little more often.

So what is new?

First of all you can now re-index videos from the context menu on the results page. When a video is re-indexed it will use the current settings. Say for example you have your video collection indexed but you now want html pages for a few videos. Go to the setting page and check the html output. Next, right click the videos you want html pages for and select the re-index option from the menu. The videos are moved to the index queue and you will get your html pages. You can also change any other option like how many images to capture or what types of templates to use.

Another simple thing that has been missing is an ability to remove videos from the result page. From the beginning the result page was just that but now when more and more people, including me, use the result page it’s nice to be able to get rid of videos that for some reason failed to index or videos that you have deleted since you indexed them.

PR: wait… I: wait… L: wait… LD: wait… I: wait… wait… Rank: wait… Traffic: wait… Price: wait… C: wait…

Fast Video Indexer is a Windows program that takes a number of videos files and automatically extracts photos from them. It can combine the extracted photos into a single collection images that gives you a clear instant view of the entire video clip. And, it can create an html page that can serve as a preview if you want to put the video on the web. In the latest version I added a new feature that now makes it possible to create an entire video preview web site for several videos.

So how do people use Fast Video Indexer?

Video professionals use it to organize videos they work with, to faster find video scenes and save time.

Video enthusiasts use it to keep track of their video collection and to quickly preview videos

I made the program to be able to browse my entire video collection even though I have most of the video files archived away.

And these are just some of the common uses. Fast video indexer is used in forensics to quickly browse evidence, to create print training materials from videos and much much more.

In this blog I will tell you about the latest improvements to the software, novel uses of the program and share some tips to get the most out of the software.

I also intend to share video related tips, software recommendation and information in general.

And, I hope to get feedback from you, my users.

If you work with videos you need to try Fast video indexer, download the free trial version and test it for yourself.

Until next time
Fredrik Lönn