[FFmpeg-user] Meaning of ffprobe output

Ulf Zibis Ulf.Zibis at gmx.de
Wed Jan 30 02:26:29 EET 2019

Am 29.01.19 um 02:31 schrieb Ulf Zibis:
> Am 29.01.19 um 01:32 schrieb Moritz Barsnick:
>> On Mon, Jan 28, 2019 at 22:52:38 +0100, Ulf Zibis wrote:
>>>> LEDs and LCDs would give you headaches if they displayed alternating lines, as the "afterglow" effect of CRTs, retaining the line's content, is not present.
>>> If each 2nd line would be empty (black) you may be right, but if the
>>> intermediate lines are filled with the content of the before frame, you
>>> have the "afterglow" effect perfectly simulated also on LCD and LED.
>> Buffering the content of the "before frame" to leave it displayed while
>> the current frame provides every other line is certainly something I
>> would call classic "deinterlacing": You are describing a display which
>> first takes both fields of a frame and combines them to a progressive
>> one.
> Yes, the software video player could transform the 25 fps interlaced
> stream to a 50 fps progressive stream as I described to feed the
> display. Then there would be no visual quality loss as known from
> deinterlacing algorithms like "weave", comparable to the quality of a
> interlaced CRT.
I think, I must correct my statement.
In my POV deinterlacing ("classic") is to buffer and optionally somehow
interpolate the content of the "before half-frame" and add it to the
current half-frame, so the display content only changes *25 times per
sec.*. But with the method I outlined, the display content (partly, only
each 2nd line) would change *50 times per sec.*. The deinterlacing then
happens in the viewers eye.
The from the software player composed stream with 50 fps than feeds the
video controller (graphics card on PC), not the display directly, which
calculates the signal for the real display according to the display's
refresh rate.
I think, this would not be rocket science and it would not wonder me, if
software like VLC really does this.


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