Video codec types.............?
I want to understand a bit more about how video codecs work, and what all the different numbers about then mean. I know simple stuff about them, and tried the wiki page on em', but its pretty complicated, and not very good at explaining it. Can anyone point me toward a site that explins it simply? or maby explain some of the slightly basic principles?
More Questions From This User See All
Answers & Comments
Verified answer
The short answer:
codec = concatenation of "encoder / decoder". Imagine giving a ZIP file, and you "expand" the ZIP file into into the actual files. The "how to expand" is what the "decoder" portion of of the codec does. Without the right codec (technically, without the right decoder) you can't "decode" the compressed video or audio data you get.
It gets complicated because different people have different ideas about HOW to encode video, so it can be played back efficiently, and what is the best trade-off between quality, size, and speed. Some encoders now give you options or presets (called "profiles").
But in general, most video codecs work by taking a "key frame" every X frames. That's sent complete (albeit with some compression). Then subsequent frames are NOT sent in full, but only the DIFFERENCE in the frames are sent (which is also compressed). This works for most videos except fast action sequences where a LOT of stuff move on the screen. There's also problems when there's a "cut" when one shot switches to another (another major change in background). That's why sometimes you see "ghost images". That's when the "key frame" was sent at the wrong time and doesn't match the cut on the screen.
Encoders generally tries to be "smart" by analyzing the video data, try to detect the scene changes, and analyze each part of the video and determine which portion needs more or less key frames.
Data rate or bit rate is related. It basically says "how much data should we use to describe the changes between frames" (see aboe). The less you use, the smaller the video is, but the lesser the quality (the changes will be recorded more "coarsely", more pixelated, using lossy compression at lower setting).
Different encoders can take the same video, with mostly the same settings, and generate different output, as some may be smarter than others doing the scene detections and smarter bit-rate selections for different segments and still maintain quality.
That's your "short explanation". :D
hi ! Its a Matroska Video flow, you ought to use ok- Lite codec p.c.. (Media participant classic) to play that report, and to transform that report to .avi or the different , you prefer entire video Converter ...........wish u have been given ur self replied.........