[FFmpeg-user] How to correctly chain filters

[Moritz Barsnick]

On Fri, Dec 07, 2018 at 03:22:56 +0100, Ulf Zibis wrote:

> I have tried 2 forms:
> $ ffmpeg -i in.vob -movflags +faststart -vf bwdif -vf hqdn3d -q 3 -c:a
> copy out_bwdif_hqdn3d.vob
> $ ffmpeg -i in.vob -movflags +faststart -vf bwdif,hqdn3d -q 3 -c:a copy
> out_bwdif,hqdn3d.vob
> 
> The 1st one results in a file of size 229 MB, the 2nd of size 328 MB.
> 
> Can anyone tell me, what is the difference of both syntax?

ffmpeg does *not* support multiple "-vf" options for the same output,
only one of them is used. (It does not warn on multiple use either,
though.) The correct syntax for chaining filters is the comma:

https://ffmpeg.org/ffmpeg-filters.html#Filtering-Introduction

    "Filters in the same linear chain are separated by commas, and
     distinct linear chains of filters are separated by semicolons."

So your second command is the one you intended.

Cheers,
Moritz