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View Full Version : General Codec Information



pvanbuskirk
September 10, 2004, 19:47:54
Hello,

I would like to capture a .AVI file with a codec that does not modify the frames in any way. I.E. I want to be able to extract the frames from the .AVI file and have them be identical to the image stream I would have gotten originally had I used ICImagingControl1.MemorySaveImageSequence command.

Could anyone tell me what codecs would be suitable for this purpose and why?

Thanks very much.

Stefan Geissler
September 13, 2004, 09:03:52
Hello,

Most codecs compress the frames or save only the changes from one frame to the next one. Every 15 (or less or more) frames a keyframe is saved, that contains the whole frame. This is to avoid artefacts.
The Microsoft RLE codec uses a lossless compression. You als can write the AVI umcompressed to a file. This would give you the best results in extracting frames.

Please have a look to the "Capturing an AVI" sample. In the codec combo box are codecs like "RGB32","RGB24" etc listed. These "codecs" will write the frames uncompressed to the AVI stream.

The file writer may decide to drop a frame. This happens, if the frames come faster than he is able to write them to harddisc. You should have a look on the data transfer rate of your harddisk and calculate, whether it is fast enough to save an uncompressed AVI stream.