Here is a test which some on this forum may find of interest. It studies the effects of copying a video clip over several generations. The videos were generated using this ffmpeg script (for h.265). The script was modified for other codecs.
ffmpeg -i C0068.mp4 -y -c:v libx265 -an gen_2.mp4
ffmpeg -i gen_2.mp4 -y -c:v libx265 -an gen_3.mp4
ffmpeg -i gen_3.mp4 -y -c:v libx265 -an gen_4.mp4
ffmpeg -i gen_4.mp4 -y -c:v libx265 -an gen_5.mp4
ffmpeg -i gen_5.mp4 -y -c:v libx265 -an gen_6.mp4
ffmpeg -i gen_6.mp4 -y -c:v libx265 -an gen_7.mp4
ffmpeg -i gen_7.mp4 -y -c:v libx265 -an gen_8.mp4
ffmpeg -i gen_8.mp4 -y -c:v libx265 -an gen_9.mp4
ffmpeg -i gen_9.mp4 -y -c:v libx265 -an gen_10.mp4
ffmpeg -i gen_10.mp4 -y -c:v libx265 -an gen_11.mp4
ffmpeg -i gen_11.mp4 -y -c:v libx265 -an gen_12.mp4
When the script is finished we have a 12th-generation video.
here is the original h.264 video from the camera:[http://www.chrisnology.info/videos/multi_gen/C0068.MP4]
Here are the 12th-generation videos for various codecs. NOTE: All of these videos play back correctly on VLC. You may have to download these files to your machine and play them locally using VLC or a similar player.
H.264
H.265
MPEG2
http://www.chrisnology.info/videos/multi_gen/mp2_gen_12.mpg
HUFFYUV
http://www.chrisnology.info/videos/multi_gen/huff_gen_12.mkv