I'm trying to concat a bunch of .mp4 videos using ffmpeg. They all play fine in VLC individually, but when I concat them together, I get frozen frames, blocky grey corruption, pixellation where the video "fades in" from blockey pixellation, and such. Can someone point me to what might be going on, so I can fix it?
Is there a way to just reencode everything? If so is there a standard good quality codec and bitrate I can use if I don't care about space or size that much, I just want good quality?