Stepok Screen Codec v2, the second generation screen codec of ours, is a specially designed codec for recording and compressing screen.
Why need compression?
If we just save screen changes in its original data, a 1 minute video would be 270MB! (using a 1024 by 768 true-colors as a sample:
1024 x 768 x 3(RGB) x 60(s) x 2(frames/sec) = 283115520B = 276480KB = 270MB )
A normal 160GB hard-drive can only save about 9 hours of video. And it would also take about 30 minutes to send a 1 minute’s video through 512K ADSL link.
Now you can see how important the compression is. A good compression will get smaller file size, and that means less space on storing and less time on sharing. Time is money, so it is well worth to find a better compression method.
For office style screen, SSCV2 can get only 100-400K output per minutes, compression ratio over 600:1 , for webpage style with many photos and animations, SSCV2 can get 2-4M per minutes, ratio over 70:1.
What is the common way to compress screen video of other software?
General screen recording software and remote controlling software has their own way to compress screen, based on LZW. Normally it has 3 steps:
- Step 1: Lower color depth from 24 bits color to 16 bits or even 8bits color.
- Step 2: Use lossless compression, normally LZW, to process I frame.
- Step 3: In P frame, do a simple comparison between this frame and last frame, then compress the changed area.
Some of them use standard MPEG serials codec to compress screen.
Neither LZW way nor MPEG is the best solution for a composed video like screen. The LZW way may have good compression ratio on text and icons, but bad performance on photos. In contrast, MPEG serials have better performance on photos but poor compression ratio on text and icons.
We need a special method, which is SSCV2.
Compared to others, how is the performance of SSCv2?