As already mentioned, GOP values can be found also with Mediainfo. Here some extracted samples among my video files: Pixel-3 recorded: mediainfo HD_H264_VID_20181218_131437.mp4 | grep GOP Format settings, GOP : M=1, N=60 mediainfo hdv01.m2t | grep GOP Format settings, GOP : M=3, N=12 mediainfo SD-BD_x264.m2ts | grep GOP Format settings, GOP : M=4, N=24 mediainfo HDV-BD_m2t_ac3.m2ts | grep GOP Format settings, GOP : M=3, N=12 Possibly slow playback can be related to old Cinelerra GOP issues, i.e. among these posts on the old list? https://www.mail-archive.com/search?l=cinelerra%40skolelinux.no&q=gop&x=0&y=... Terje Den 09.02.2019 11:39, skrev Igor BEGHETTO: What I know, to NLEs don't like great value GOP because the I-frame are very distance. I-frames (Intra frames) contains all the information of the image, P-frames (Predicted frames) and B-frames (Bidirectional predicted frames) not. Greater GOP value is, smaller file size is (it is good for streaming and delivery); smaller GOP value is, greater file size is and more I-frames there are and then it is good for editing video. With more i-frames cpu consumes less because decode less information. For video archive would be better GOP=1 (all i-frames) Sorry, I guess, you always know that. However, you have a i7 cpu with a lot of RAM, then your PC should process your video very good, I think. Have you tried to use Proxy with scale value to 1/2, just for testing? If Proxy with "mpeg" you do, the GOP value is 12, then could be very useful. (I think, I am writing like Joda Jedi speak) ;-) IgorBeg Il 08/02/2019 23.41, Andrea paz ha scritto: Thanks for the script. Max GOP = 250 Meldingsteksten vil bli nedlastet etter behov.