code source of opencv using ffmpeg

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Hi,

I know that opencv use ffmpeg to encode/decode vidoe, and I am interested in studying it for personal reuse. The problem is that I read the sources in the directory /opencv/opencv/modules/highgui/src (all the file with ffmpeg in the name) but haven't been able to locate the function which encode decode data. Can you help me finding it ?

Any help would be appreciate. Thanks.