Convert game replay into video format

Question

My game outputs a replay file for each individual game and allows the player to watch past games.

Just a quick example of what our replay files look like:

m 6 2098.25 917.125 -1 0 224 56ööööö843949615
m 2 1715.25 1835.25 1 0 224 44ööööö843949621
m 11 1661.125 1890.875 1 0 224 56ööööö843949627
m 5 1818.125 929.0 0 1 224 56ööööö843949633
death 9 3 4 5ööööö843949663
hit 9 3 4 48 26 2114 1987 2.8266926 1865 1891ööööö843949663

Some info on the identifiers:

Movement: // m (player id) (x coord) (y coord) (x-movement) (y-movement) (remaining health) (shot energy remaining) (timestamp)

Death: // death (dead player id) (killer player id)

Hit: // hit (hit player id) (hitter player id) (weapon (1-4)) (damage dealt) (life remaining ) (x coord) (y coord) (angle of hit) (total damage dealt) (total damage taken)

There are a lot more than what I listed, but you get the idea.

What's in the replay files are essentially the same as what is sent to the server during a live game.

Right now, if we want to take a video of the game, we just go into our replay system and record it with Fraps, but I'd like to convert our replays into some kind of video format.

I know this may be a bit far-fetched, but I thought I'd give it a shot here.

The game is written in Java and is sprite based.

Answer 1

Building a good video capturing system into your game is going to be quite challenging. Especially if you want to record in real-time. If your replay system allows for a slower playback, then it's going to be easier to avoid frame skips etc., but then you'll have a problem with audio recording.

You should test if you have enough CPU cycles to record in real-time, or if you need to capture video with a lower frame-rate and then "record" audio separately.

I don't know what technology you use for rendering, but getting rendered frames shouldn't be too hard. When using OpenGL you could use a render-to-texture approach. In any case I suggest you have a look at an existing recording API like Xuggler. It will allow you to add separate frames to a buffer that will then be encoded to a video file. They also have some tutorials that might help you getting started.