When I split mp4 with Allok Video Splitter video is choppy/blurry

[cool09]

I've used Allok Video Splitter for 10 yrs or so and it is quick and does a good job but I notice that sometimes the split video is not as clear as the original mp4 and a little choppy/blurry in both Windows Media Player and VLC Player. This happens a lot when I split H264 mp4. I configure the output mp4 as the same as the original and the frame rate as the original. There's options to set the output mp4 to H264 but that takes a long time. How should I split the video so the quality comes out the same as the original? I don't want to change to different software.
I also have avidemux but when I set the video output as mp4 H264 it comes out as mkv not mp4. Do I also have to set the Video to mp4 muxer in avidemux?

[2nHxWW6GkN1l916N3ayz8HQoi]

Do I also have to set the Video to mp4 muxer in avidemux?

Yes. MP4 Muxer as well.