[FFmpeg-user] Record N RTSP frames and average into 1 jpg? In a loop?

David Bernat david.bernat at gmail.com
Tue Jul 11 18:29:47 EEST 2023

On Mon, Jul 10, 2023 at 1:33 PM Carl Zwanzig <cpz at tuunq.com> wrote:

> On 7/9/2023 3:46 AM, David Bernat wrote:
> > As for EE solutions, all you really need is to pass the AC current
> through
> > a full-wave rectifier before the LEDs.
> Not exactly, an LED is a "negative resistance" device- the higher the
> current the lower it's resistance. They need some kind of a current
> limiter
> so as not to self destruct. This can be as simple as a resistor or as
> complex as an externally-controlled PWM supply (for dimming). Consumer LED
> lamps have some sort of constant-current regulator to maintain near
> constant
> output with variations in line voltage. This could include a
> high-frequency
> power supply in the higher-quality lights.
> > By the way, it has been a while, but I*think*  back of the envelop
> > calculation allows this:
> > US AC current: 60 Hz.
> > Half-Wave Rectification: 30 Hz.
> Half-wave rectifying gets you 60 half cycles, full gets 120 (it "folds"
> the
> halves from one polarity to the other).

"Your" correct. It was a typo on my part. :)
If you are going to solve the problem some other way; this is the solution.
Sounds like your bash loop will work for what you need.

> As I mentioned before, try some different LED lights to see if they still
> show the problem, then you'll know where to put the effort. Or try a
> different camera. Or try to pull stills from the camera instead of motion
> video.
> In the end, no matter how much processing is done, it's still
> garbage-in/garbage-out, post-processing can't make up for missing
> information.
> Later,
> z!
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