[FFmpeg-user] What is 'yuv420p(tv, smpte170m, progressive)'?

[Mark Filipak]

On 05/19/2020 10:43 AM, Moritz Barsnick wrote:
> On Tue, May 19, 2020 at 09:56:51 -0400, Mark Filipak wrote:
>> If ffmpeg uses "smpte170m" with "progressive" to denote hard
>> telecine, then I want to detelecine first.
> 
> I thought it was understood that "smpte170m" is a notation for a
> colorspace or color encoding (in the widest sense), while "progressive"
> says something about frame/field order and relation of frames/fields to
> each other.

SMPTE standard 170M, "Composite Analog Video Signal – NTSC for Studio Applications"

> How does "smpte170m" have anything to do with your
> deinterlacing/bobbing/frame doubling?

Not explicitly. It defines NTSC-M signalling (which includes the use of "c" colorimetry) but also 
all the properties of NTSC-M broadcast analog video including features of the carrier and 
bandwidths. Broadly it defines alternating-line fields that differ in time by 1/(field_rate) seconds 
where field_rate = 60000/1001Hz. I'm not terribly familiar with DVB or ATSC, but ATSC is based on 
NTSC-M.

Regarding why "smpte170m" & "progressive" & "top field first" and other notations appear to be 
arguments to a supposed yuv420p() function, well, you'll have to ask the developers.

>> I value your input, but I need to understand it to make use of it. I
>> hope that I've added enough distinction that it now makes sense. And
>> I hope you and others will post back.
> 
> Not quite. Carl Eugen's friendly Google link could have explained what
> SMTPE 170m (even if the first hits reference "analog[ue]"), but you
> claimed "I know what SMPTE 170M is". I don't understand how the two
> concepts relate, so you would need to elaborate on that.

Carl Eugen didn't need to elaborate because SMPTE 170M *is* the U.S. *analog* TV standard. When 
someone cites "SMPTE 170M", they refer to NTSC-M.