[CinCV TNG] Fwd: to create time scaled media

Good Guy good1.2guy at gmail.com
Wed Sep 13 02:43:37 CEST 2017


>
> The limit is now somewhere between speed 150 and speed 160, before the
> audio is muted


On my machine, the render works at least to 1000x, but I have to play it at
half speed because I think the audio board maxs out at around 10K.  I
created a 10Hz base media FFMPEG qt v=mp4,a=s16le using titler and aeval.
I was able to render the 1hr (3600secs) at 1000 for 3.5 secs.  The playback
on ffplay is not audible, as it is in cln5 at normal speed, but it clearly
can be
heard at half speed playback.  Seems to work at least to 1000x on my system.

It seems likely that you have encountered a new limit somewhere on your
system.  One effect I saw, was that filling the now 1000x longer audio
buffer
takes some time.  There may be other exaggerated resource demands.

Phyllis is going to note these observations, and indicate that the results
may start to buckle as the demands go over 100x.

This is what I described?!


yes, just wanted to re-emphasize this since the slider bar is longer than
the
track is high.  Makes it a little more precise, but it would be nice if
there
was an easy way to enter exact decimal data.  This is possible if you mod
the EDL directly by editting the xml session, but I only do this sort of
thing
if it really is the only way.

I have a rule about adding work to code.  If the coding work is harder than
all of the work it will ever recover, it is not worth it.  I suspect that
adding
textual data entry would be a low value return, and may never recover the
time I would have to invest to add it, though I would not turn down patches.

BTW.  I very much appreciate the time you have put into testing and
reporting.
I know it is difficult and time consuming.  We are wondering... why do you
want to playback at 100-1000x ?  Most media looks weird this fast/

gg



On Tue, Sep 12, 2017 at 4:00 PM, Frederic Roenitz <ml1 at aimvis.de> wrote:

> It works, thank you!
>
> The limit is now somewhere between speed 150 and speed 160, before the
> audio is muted.
>
> A hint about this limit in the documentation might be a good idea.
>
>
> > but looks like high speeds may require big limits.  Speed kills.
>
> My thoughts about sane speed limits
> ===================================
>
> Taking 20KHz (20.000Hz) as the upper human audible limit and the
> roughly last speed before the mute limit at speed 150:
>
> 20000Hz/150 == 133Hz
>
> Keeping this in mind and now:
>
>
> To sample something we need at least a sample rate of (a bit more
> than) twice the frequency we want to sample.
>
> We need a sample rate of 44KHz to sample up to about 22KHz
> frequencies.
>
> Default these days is often a sample rate of 48KHz which allows us to
> sample up to 24KHz frequencies.
>
>
> Taking 16Hz as the about lowest human audible frequency:
>
> 24000Hz/16Hz == 1500
>
> would mean to have speed 1500 as the limit before the mute limit.
> (Don't know, but might cause resource problems.)
>
> Currently the last speed before the mute limit is roughly speed 150:
>
> 24000Hz/150 == 160Hz
>
>
> So at speed 1 we have a range from 16Hz to 160Hz that would roughly
> still be audible at speed 150.
>
> ... for now, the speed limit at speed 150 is enough for me. ;)
>
>
>
>
> >> How can I easily see which value a speed handle has? Currently I can
> >> drag it a bit and look at the status bar and guess how far I dragged
> >> it. Or I can right click -> speed -> click the fader nob. Both ways
> >> are quite complicated.
>
> > To see auto slider bars with more precision, set up your auto
> > as usual, and then use btn3 (rt mouse) to click one of the auto
> > keyframes on the timeline.  A popup menu will show which has
> > the auto type (speed) as the first menu item.  Click this menu
> > item, and a speed colored slider bar will appear.  You can only
> > click it once.  When you click the slider, press and hold down btn1
> > and move the slider to update the auto value.  A tooltip will show
> > the slider value.  When you release the button, the slider will be
> > deleted from the canvas, and the value will be updated.  Sadly,
> > the update is not ganged by double clicking.
>
> This is what I described?!
>
> Could:
>
> > A popup menu will show which has the auto type (speed) as the first
> > menu item.
>
> be supplemented with an additional textfield near the "speed" menu
> entry? This textfield would contain the current position as a number
> (so that I can directly see it) and as a bonus: Could this textfield
> be directly editable?
>
> Example popup menu:
>
>  speed: 1.23
>  Hide keyframe type
>  Delete keyframe
>  [...]
>
>
>
> Thanks for autos.C, I will have a closer look at it these days
>
>
> Kind greetings
>
> Frederic
>
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