size

I have Xiaomi smartphone with Android operating system in it. Whenever I record something using the front camera, even if just for a few seconds, the recorded video file size comes out to be very large as compared to the duration of the video. I say this because I have previously downloaded...

What should be the exact size of the photo used for my channels profile image? Also, what should the exact size of the image be for my channel banner photo too? :P If anyone could let me know, it would be appreciated, Thanks, Sean! :D :D