[mythtv-users] Why are recording thumbnails png instead of jpg?

Stephen Worthington stephen_agent at jsw.gen.nz
Sat Feb 2 09:46:01 UTC 2019

On Sat, 2 Feb 2019 03:14:37 -0500, you wrote:

>Just wondering why the recording thumbnails are png instead of jpg, which
>is better for photos.
>I just converted one png to jpg and went from 1.46MB to 208KB. With a lot
>of recordings that adds up to a nice chunk of space savings.

Use of the JPEG format is governed by licensing agreements - you have
to pay.  Using PNG is free.

And in any case, the size of the resulting file depends on what
settings you use for compressing it.  You can make any picture file
smaller by using settings that cause more compression (at the expense
of quality).  So it is extremely likely that your JPEG conversion was
simply lower quality than the original PNG file.  And to be a proper
test, you would need to create your JPEG from the original source
frame of the video file that the PNG was created from.  Creating it
from the existing PNG is always going to create a lower quality result
- all lossy compression algorithms by definition cause loss - which
means loss of quality.  So no matter how good the JPEG compression
algorithm was, the JPEG file will have a bit more loss than the
original PNG.

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