squared pixel vs rectangular pixel

[papcom]

I often work with PAL 756x720 files. If These files are displayed with square pixel then the aspect ratio is wrong and tge content shows slightly squeezed. The files have to be displayed with rectangular pixels or recalculated as 768x576 which is the correct PAL square Pixel Format.

How can I output 720pixel files to 768pixel in avisynth? do I really have to scale these videos? ...or is there another approach?

[vivan]

How can I output 720pixel files to 768pixel in avisynth? do I really have to scale these videos? ...or is there another approach?Avisynth works with pixels, it doesn't work with metadata (aspect ratio is just metadata).
If you want to encode your video as 768x576 with square pixels - you have to scale.
If you want to encode your video as 720x576 for it be scaled by video player to 768x576 - you don't have to scale, you have to set stream metadata right. If you're using x264 - check --sar (http://www.chaneru.com/Roku/HLS/X264_Settings.htm#sar) option, if you're using different encoder - check it's settings for something similar.

[papcom]

thank You very much @vivan ...very good explained.

[johnmeyer]

A pixel is a pixel. The square vs. rectangular conversion happens when the video is played. Thus, if you have a player that understands the PAR flag, you don't need to change anything.

[kuchikirukia]

I often work with PAL 756x720 files. If These files are displayed with square pixel then the aspect ratio is wrong and tge content shows slightly squeezed. The files have to be displayed with rectangular pixels or recalculated as 768x576 which is the correct PAL square Pixel Format.

How can I output 720pixel files to 768pixel in avisynth? do I really have to scale these videos? ...or is there another approach?

Sounds like you need to remux, setting the appropriate DAR.