[FFmpeg-user] Enhancing filters

Mettavihari D tv.lists at gmail.com
Fri Aug 24 06:45:40 EEST 2018


>> I have some low resolution videos which I like to enhance the quality of.
>> I have found the following filters to be useful.
>> unsharp and smartblur.

>> I would like to have some other ideas on how to sharpen and enhance video
>> files.

> You don't say what quality problems you want to address, but some approaches you can consider:
> - proper de-interlacing (or proper interlaced processing)
> - frame-rate correction
> - exposure correction/contrast enhancement
> - colour correction
> - debanding
> - stabilisation
> - denoising

I have a set of 2mbit/s videos which I need to stream out to a cable
net provider
The suggestion is that the present 2Mbit/sec files be converted with
the below script

ffmpeg -y -i  $FILE1.mp4 -preset slower -profile:v main -level 3.1 -s
720x576 -c:v libx264 -r 25000/1000 -b:v 1750k -maxrate:v 1750k
-minrate:v 1750k -bufsize:v 350k -color_primaries 1 -color_trc 1
-colorspace 1 -c:a mp2 -b:a 128k -nal-hrd cbr -muxrate 2100k -f mpegts

this generates the Transport stream files and this works OK

I also have a set of 512 Kb/sec files which I also have to stream out
to the same provider.
This quality is of cause not so good and I would like to enhance them
before streaming.

This is a link to a sample file.

This video has been shot on a green chroma background and due to
lighting weakness, you see a lot of unsharp and blurred edges.
The image itself is compressed to a low resolution at which I have
also lost a lot of quality.

I have tried using
ffmpeg -y -i test.mp4 -strict -2 -vf
smartblur=1.5:-0.35:-3.5:0.65:0.25:2.0 -f mp4 test5.mp4
ffmpeg -y -i test.mp4 -strict -2 -vf
smartblur=lr=2.00:ls=-0.90:lt=-5.0:cr=0.5:cs=1.0:ct=1.5 -f mp4

I do get a better result, but the problem I have is, that I do not
understand the settings given in these 2 examples.
I would like to understand why I do something, but the color space is
not an area I have understood well.

Any help in understanding this, and suggestions what to do, is very
much appreciated.

with metta

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