How to set the video resolution over composite?

Question

I am trying to make a RPi 1 work nicely with an old LCD PAL TV (Sony KLV-20SR3). The video signal goes over composite (over SCART) because HDMI is not available. I am using LibreELEC.

By default the picture overflows the screen, but playing with overscan_scale=1 and overscan_{left,right,top,bottom} I can make the display area right. The results are, however, ugly.

I suppose the problem is due to the fact that the RPi thinks that the resolution of the screen is 720x576 (probably due to sdtv_mode=2 #PAL) while the resolution of the LCD of this TV is exactly 640x480. I suppose that scaling the framebuffer is what makes everything blurry.

I tried setting framebuffer_width=640 and framebuffer_height=480 but the screen resolution is still the same. (If I read http://elinux.org/RPiconfig correctly, these settings work only for the console.)

How can I set the video resolution when using the composite output?

Answer 1

I read at https://discourse.osmc.tv/t/composite-sd-resolution-of-osmc-skin-video-output/5445/3) that

Composite is fixed resolution (720x480@60i for NTSC, 720x576@50i for PAL).

So you cannot change it.