[FFmpeg-user] ffmpeg architecture question #2

[Mark Filipak]

On 04/24/2020 05:10 AM, Mark Filipak wrote:
> Hello,
> 
> I've been told that, for soft telecined video
> 
> |<--------------------------1/6s-------------------------->|
> [A/a__________][B/b__________][C/c__________][D/d__________] source
> 
>  the decoder is fully compliant and therefore outputs 30fps
> 
> |<--------------------------1/6s-------------------------->|
> [A/a__________][B/b__________][C/c__________][D/d__________] source
> [A/a_______][B/b_______][B/c_______][C/d_______][D/d_______] hard telecine
> 
> I've also been told that the 30fps is interlaced (which I found surprising)
> 
> |<--------------------------1/6s-------------------------->|
> [A/a__________][B/b__________][C/c__________][D/d__________] source
> [A/a_______][B/b_______][B/c_______][C/d_______][D/d_______] hard telecine
> [A/-_][-/a_][B/-_][-/b_][B/-_][-/c_][C/-_][-/d_][D/-_][-/d_] i30-TFF
> 
> Is this correct so far?

(No response, so continuing.)

When I do 'telecine=pattern=5', I wind up with this

|<--------------------------1/6s-------------------------->|
[A/a_][A/a_][A/b_][B/b_][B/b_][C/c_][C/c_][C/d_][D/d_][D/d_] 55-telecine

I have confirmed it by single-frame stepping through test videos.

So, if the 'i30, TFF' from the decoder is correct, the following must be the full picture:

|<--------------------------1/6s-------------------------->|
[A/a__________][B/b__________][C/c__________][D/d__________] source
[A/a_______][B/b_______][B/c_______][C/d_______][D/d_______] hard telecine
[A/-_][-/a_][B/-_][-/b_][B/-_][-/c_][C/-_][-/d_][D/-_][-/d_] i30, TFF
[A/a_______][B/b_______][B/c_______][C/d_______][D/d_______] deinterlace
[A/a__________][B/b__________][C/c__________][D/d__________] detelecine
[A/a_][A/a_][A/b_][B/b_][B/b_][C/c_][C/c_][C/d_][D/d_][D/d_] 55-telecine

Now, I'm not telling ffmpeg to do the deinterlace or the detelecine. If it indeed is doing 
deinterlace & detelecine -- I don't know how to get from i30-TFF to 55-telecine any other way -- it 
must be doing it on its own.

Is this correct?