[Cin] Suggestion: improve setting for VP9 webm

[Phyllis Smith]

>From my quick read, it sounds like a thorough analysis and great
suggestion.  I will have to read and look at all of this more carefully so
it can be updated accordingly.  And hopefully, Andrew or Andrea will have
time to comment too.  ...Phyllis

On Sat, Sep 24, 2022 at 3:32 PM Miroslav Rovis via Cin <
cin at lists.cinelerra-gg.org> wrote:

> It's simple, and my wording may not be quite precise, but you guys and gals
> will understand.
>
> So, when using the setting in the render window, I figured out that there
> are
> better settings to use than the presets that are offered. And they are
> simpler
> too.
>
> In essence, the Wiki page for VP9 can tell you all:
> https://trac.ffmpeg.org/wiki/Encode/VP9 [*]
>
> I have no rendering, actually no Cinelerra opened right now, so, from
> memory:
>
> It's just b=0, then add crf=31 (or other number), and then row-mt=1, and
> remove
> the min and max settings from the preset.
>
> I did use b=0 (which would correspond to -b 0 in the VP9 wiki page (but I
> see
> only -b:v 0 in the page). And it did work I can tell you.
>
> However, see there around:
> "more contemporary CRF-style approach for the final pass to achieve a
> certain perceptual quality"
> and there is -b:v 0 in the second pass.
> and around:
> "must use a combination of -crf and -b:v 0. Note that -b:v MUST be 0."
>
> Also find:
> "FFmpeg added support for row based multithreading in version 3.4,
> released on
> January 25th, 2018. As of libvpx version 1.7.0 this multithreading
> enhancement
> is not enabled by default and needs be manually activated with the -row-mt
> 1
> switch."
> which I find works great as well on my systems. They are relatively new:
> AMD Ryzen 7 PRO 4750G
> and also one:
> AMD Ryzen 7 5700G
> so if the above maybe would not work well on older machines, then, don't
> know...
>
> So, this is a suggestion to improve the VP9 webm presets in Cinelerra
> FFmpeg.
> While I am getting better at understanding the source code, I would still
> probably be to slow to find it and change it and send a patch myself. Too
> slow.
> And that would take me more time than I can set apart at this time.
>
> Regards!
>
> ---
> I've been using VP9 (previously VP8) webm a lot. E.g. anywhere you go from:
> https://www.croatiafidelis.hr/2022/
> or, to take just one sample (4 minutes):
>
> https://www.croatiafidelis.hr/2022/Jazovka/VID-2022-06-22-1034-Jazovka-procesija.webm
> It's nothing but motion plugin set up, blur plugin in the bottom video at
> 100%,
> and go render. Then work the audio separately, mux and post. Of course, the
> stabilizing is slow, motion plugin takes long to calculate.
>
> But all those people moving can be scrutinized in a lot of detail, as if I
> filmed with a mobile phone attached to a good stabilizer, and instead, the
> original was a shaky video as ever, because I held the mobile with just my
> hand.
>
> Cinelerra can stabilize you videos well. It's worth the time-expensive
> learning curve to get to know how to do it.
>
> Here are some comparison videos with both the shaky and stabilized video
> (however I've gotten better since then, these are all old, but I have no
> other
> comparisons)
>
> e.g. from:
> https://www.croatiafidelis.hr/2019/
> the videos e.g.:
>
> https://www.croatiafidelis.hr/2019/Jaska/190824-Jaska-Vukovic-demo-1-stabilize.webm
> or from:
> https://www.croatiafidelis.hr/2015/Macelj/Macelj-2-cmp.php
> the video being:
> https://www.croatiafidelis.hr/2015/Macelj/150607-Macelj-HebrangCOMP.webm
>
> --
> Miroslav Rovis
> Zagreb, Croatia
> https://www.CroatiaFidelis.hr
> my PGP-key:
> https://www.croatiafidelis.hr/FCF13245ED247DCE443855B7EA9884884FBAF0AE.asc
> --
> Cin mailing list
> Cin at lists.cinelerra-gg.org
> https://lists.cinelerra-gg.org/mailman/listinfo/cin
>
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