Hi

I added a movie clip to the time line and in front of the clip I added 1 PNG image.

I rendered the movie as mp4 at 640x360 30 fps (the same as the original movie clip)

However the original movie clip only was 98 MB, while the rendered movie is 194 MB!!! I checked used a movie player: both files (original and rendered) are mp4 and have 640x360 30 fps

How can inserting a single PNG image in front of a movie clip in the time line (the image only plays for 5 seconds), almost double the file size?

Is there some option you must enable to keep the same movie quality as the original movie clip?

Jessica

"codec copy" does not allow to precisely cut a video, and certainly not to alter it (adding effects or overlays...)
so you must re-encode the modified frames... so you must find the proper codec settings to achieve the desired quality/filesize balance.
play with the quality slider to reach similar file size, and check visual quality is adequate...