[FFmpeg-user] For discussion: A better video notation.

[Mark Filipak (ffmpeg)]

On 02/04/2021 10:54 PM, Jim DeLaHunt wrote:

Thanks, Jim,

> On 2021-02-04 15:50, Mark Filipak (ffmpeg) wrote:
> 
>> For discussion: A better video notation.
>>
>> 24PPS at 23.9FPS         (aka "24p") Cinema (i.e. 24PPS) mastered at 23.9FPS, 0.1% slow.
>> 24PPS at 23.9FPS         (aka "30i") Soft-telecined: cinema with 29.9FPS metadata, 0.1% slow.
> 
> The notation codes for these two examples look identical to me.

They _are_ identical. A soft-telecined video is actually 23.9fps but with 29.9fps metadata. In other 
words, you wouldn't want to detelecine it, eh?

> Perhaps the second one should have been "30PPS at 29.9FPS"?
> 
> Also, I'll point out that that this notation seems to have an obfuscation of its own, when it says 
> "23.9". Does that actually mean "24/1.001"? ...

You know, I'm kinda ambivalent. Of course, 24/1.001fps needs to be differentiated from 24fps, but 
I'm not sure 24fps actually exists on any DVD or BD. That 'said', I originally used '/1.001' but I 
thought that it added nothing other than that it's not 24fps or 30fps or 60fps. Now, it's a fact 
that there are several players and software packages that use '23fps' and '29fps' and '59fps'. I 
understand why they do that though I don't like it much and first thought it was an error. I thought 
that '23.9', '29.9', and '59.9' was a good compromise. But I'm pretty agnostic on the whole issue. 
Let's see what consensus emerges.

>... It would be nice if the notation said that, so that we 
> could distinguish it from the number, "239/10".
> 
> Best regards,
>       —Jim DeLaHunt

-- 
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