Combining Filters with Normal Options

Question

What is the difference between using an option as a Filter vs a Normal option?

Should I always use Filters instead of Normal options when possible?

Will they still work if you combine them together? Or should you use always use related ones together with their same method?

Examples

Scale and Algorithm

All Filters

-vf "scale=-2:720:flags=lanczos"

Filter Scale, Normal Algorithm

-vf scale=-2:720 
-sws_flags lanczos

Aspect Ratio SAR and DAR

All Filters

-vf "setsar=1:1,setdar=4:3"

Filter SAR, Normal Aspect

-vf setsar=1:1 
-aspect 4:3

Pixel Format and Quality

Filter Pixel Format, Normal Quality

-vf format=yuv420p
-preset medium -b:v 2500K

Normal Pixel Format, Normal Quality

-pix_fmt yuv420p 
-preset medium -b:v 2500K

Gyan Gyan · Accepted Answer · 2019-03-16T05:57:55

In -vf "scale=-2:720:flags=lanczos,crop=..,scale=-2:360", the algorithm is only set for the first scale, whereas -sws_flags lanczos will apply to all instances of scale. If you're sure, you want it to apply to all, then use the latter form. Also, at present, filter_complex filters won't pick up -sws_flags or -swr_flags. You have to set flags within filters. (It's on my todo list).

-aspect 4:3 can be used with streamcopy. Obviously, the filter variant can't. But aspect will override any filter-set SAR, and could potentially be invalid. So, use only when you're sure, or need to force a known value.

-pix_fmt yuv420p will force this value as the final pixel format from the filtergraph. format can be modified later on by other filters. The filter format can still be auto negotiated with the encoder, in both cases.