[FFmpeg-user] croping a video while keeping the rest of the data in the container

Greetings, I want to the following, take a mkv file (with multiple audio and subtitles included for example) and crop the video so in the end I have same file like the original but with the video stream cropped. how I can do that? Thanks. ___ ffmpeg-

[FFmpeg-user] invalid AVPacket size in av_read_frame usage.

Greetings, I'm writing a program that needs to sample the screen in bgra format. the problem is what I try to read an av frame, I get this error: [rawvideo @ 0x1403aa0] Invalid buffer size, packet size 1228800 < expected frame_size 8294400 looking at the code I see that unless stated else, 1