[Cin] Suggestion: improve presets for VP9 webm

[Miroslav Rovis]

I changed the subject line: 's/setting/presets/'.

On 220924-17:55-0600, Phyllis Smith wrote:
> 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
I'm not an expert, but I am an advanced user. Unfortunately, a
slow user too.  I'm probably correct (except for imprecise
wordage) about this.

Because (see below)...
 
> 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.

Because in this wiki page:
> > In essence, the Wiki page for VP9 can tell you all:
> > https://trac.ffmpeg.org/wiki/Encode/VP9 [*]
previously there were recommendation on VP9 that correspond with
the current presets in Cinelerra. The current version of VP9
wiki page is, I believe, just a few months old.

With the presets that I find in current Cinelerra; I'm yet to
open it today and work with it, but I choose preset that are
recommended for 1920x1080 30fps and then edit it as below.
> > 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 have issues with motion plugin (or related to it). So I'll
reuse this part below (which is missing a [*] at the start, as I
meant the [*] above to refer to it) in a new, separate thread,
not so much related to FFmpeg VP9 presets.
> > 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
> >

-- 
Miroslav Rovis
Zagreb, Croatia
https://www.CroatiaFidelis.hr
my PGP-key:
https://www.croatiafidelis.hr/FCF13245ED247DCE443855B7EA9884884FBAF0AE.asc
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