How can I reduce compression with libx265?

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How can I reduce compression with libx265?

Mark Filipak
I transcoded from H.264 to x265 and the target is too compressed -- faces are waxy.

I tried the general directive '-compression_level 1'. I tried '-compression_level 6'. The results
are identical (by 'identical', I mean the exact same file size and playback appearance). So the
'-compression_level' directive doesn't do anything.

Source video is 11 GBytes.
Target video made is 300 MBytes -- way too small (too compressed).

The x265 coder is documented here:
https://ffmpeg.org/ffmpeg-codecs.html#libx265
There's no documentation in the documentation -- I would write "There's no 'there' there" but the
younger audience wouldn't know to what I refer.

How can I reduce compression with libx265? Is 'preset' the way? Is 'tune' the way. There's not only
no documentation for them, there's not even an indication of parameter type or range (or even if
they take parameters -- the lack of documentation is shameful).
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Re: How can I reduce compression with libx265?

Moritz Barsnick
On Mon, Mar 30, 2020 at 10:03:26 -0400, Mark Filipak wrote:
> The x265 coder is documented here:
> https://ffmpeg.org/ffmpeg-codecs.html#libx265
> There's no documentation in the documentation -- I would write "There's no 'there' there" but the
> younger audience wouldn't know to what I refer.

Very well explained here:
https://trac.ffmpeg.org/wiki/Encode/H.265#Ratecontrolmodes

I usually use CRF (as with libx264).

> How can I reduce compression with libx265? Is 'preset' the way? Is 'tune' the way. There's not only
> no documentation for them, there's not even an indication of parameter type or range (or even if
> they take parameters -- the lack of documentation is shameful).

The relation to presets is also explained.

Cheers,
Moritz
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Re: How can I reduce compression with libx265?

Mark Filipak
On 03/30/2020 10:34 AM, Moritz Barsnick wrote:

> On Mon, Mar 30, 2020 at 10:03:26 -0400, Mark Filipak wrote:
>> The x265 coder is documented here:
>> https://ffmpeg.org/ffmpeg-codecs.html#libx265
>> There's no documentation in the documentation -- I would write "There's no 'there' there" but the
>> younger audience wouldn't know to what I refer.
>
> Very well explained here:
> https://trac.ffmpeg.org/wiki/Encode/H.265#Ratecontrolmodes
>
> I usually use CRF (as with libx264).
>
>> How can I reduce compression with libx265? Is 'preset' the way? Is 'tune' the way. There's not only
>> no documentation for them, there's not even an indication of parameter type or range (or even if
>> they take parameters -- the lack of documentation is shameful).
>
> The relation to presets is also explained.

Hi Moritz,

And thanks so much. If you could see me, you'd see my big smile. That stuff at the end of those
links could be the documentation for HandBrake! (which also has little documentation). ...The
HandBrake folks insist that HB is not an ffmpeg frontend... It is to laugh.

You know, it would be really helpful if someone would simply put those links in the ffmpeg coder
documentation for libx264 & libx265.

Kindly thank whomever wrote that stuff.

...Next day...
I submitted this command line:

ffmpeg -i IN.M2TS -vf "telecine=pattern=5555,bwdif=mode=send_frame" -c:v libx265 -crf 20 -preset
slow -c:a copy -c:s copy OUT.MKV

and paused this message and went to bed.

...Today (right now) I'm viewing OUT.MKV. It is the most awesome transcode I've ever seen. The
5-5-5-5 telecine works as I'd hoped it would, as I knew it would. It is the first ffmpeg success
I've had.

Thank you all for your help. Joy, joy, joy.

Ciao,
Mark.
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