[FFmpeg-user] Scaling up is pixelated

Carl Eugen Hoyos cehoyos at ag.or.at
Wed Feb 12 23:59:19 CET 2014

Moritz Barsnick <barsnick <at> gmx.net> writes:

> On Wed, Feb 12, 2014 at 07:22:39 -0800, Grant wrote:
> > ffmpeg -i sample1.mp4 -filter:v scale=1360:-1 
> > -sws_flags lanczos -c:a copy sample2.mp4

Out of curiosity: Do you see a different quality 
between lanczos and default (with -qscale 2)?

> You're recoding to larger dimensions with a less 
> efficient codec (implicit) with a smaller bitrate 
> (observed). That should explain the drop in quality.
> Try explicitly increasing the quality of the output, 
> e.g. by specifying "-q:v 2".

This seems correct, thank you.

> (I must admit I don't know what the "quality" 
> defaults to when encoding the way you did.


Carl Eugen

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