I've used FFmpeg to extract all the I-frames from a MKV/MP4 file but FFmpeg seems to decode all frames to do it, so it takes a very long time if the video file is 1080p and longer than 10 minutes. I only want it to jump from I-frame to I-frame and dump them out to JPG/PNG files. Also, I need to know the timestamp of the I-frame.
The other option was to use FFprobe to get timestamps for all the I-frames, but that also decodes the whole file.
I'm trying to do something similar to Avidemux. In Avidemux you can step to each I-frame very fast by just pressing the up or down arrow keys, but it does so without decode all the B/P frames.