Basically, any processing will technically degrade the video quality.
So, answering your title-question: Yes
Sorry, but what you write about aspect ratios does not make sense to me.
For further details about PAR&Co, reading [INFO] About pixel aspect ratios,.. and the linked articles there might help.
If your source is not properly flagged and hasn't a 1:1 PAR, you should set the 'Input PAR' to the correct values.
If you want the minimal possible distortion, then set the output PAR you aim for and set just the width. (Do not disable 'Auto adjust'.)
What you are doing might be correct for your source, and I might just not understand you correctly.
Like I wrote: Yes, whatever you do you technically lose quality.
(using non-square pixels will technically additionally alter the video quality
)
Cu Selur
So, answering your title-question: Yes
Sorry, but what you write about aspect ratios does not make sense to me.
For further details about PAR&Co, reading [INFO] About pixel aspect ratios,.. and the linked articles there might help.
If your source is not properly flagged and hasn't a 1:1 PAR, you should set the 'Input PAR' to the correct values.
If you want the minimal possible distortion, then set the output PAR you aim for and set just the width. (Do not disable 'Auto adjust'.)
What you are doing might be correct for your source, and I might just not understand you correctly.
Like I wrote: Yes, whatever you do you technically lose quality.
(using non-square pixels will technically additionally alter the video quality
)Cu Selur