[Cin] Anamorphic 16:9 SD-DV(D) widescreen to AV1.webm

[Phyllis Smith]

Andrea, an explanation in the manual would be a good addition.  I have read
what you wrote and studied a little of what I could find online, and am
still somewhat confused so am unable to determine if your explanation
sounds correct.  But it seems to fit. ...Phyllis

On Fri, Jan 12, 2024 at 1:40 AM Andrea paz via Cin <
cin at lists.cinelerra-gg.org> wrote:

> > Also, pixel aspect ratio (PAR) is also known as sample aspect ratio
> (abbreviated SAR) in some industrial standards (such as H.264[2]) and
> output of programs (such as ffmpeg
> > Note 3: "ffprobe shows PAR as SAR". ffmpeg.org. Retrieved 2022-06-10.
>
> Yes, exactly. That is what confuses me.
> The theory is simple: DAR = PAR x SAR
> DAR and SAR are "frame aspect ratio," PAR is "pixel aspect ratio." It
> can be said that when SAR (let's imagine it as Width x Height pixels,
> although it can be expressed as a ratio) is different from DAR we have
> an anamorphic video and on the Compositor we see the deformed image.
> Then we intervene with PAR which enlarges or shrinks the pixel so that
> SAR is equal to DAR again.
> A possible first confusion is that SAR and DAR can be expressed as
> both Width x Height and aspect ratio. Another thing that can be
> confusing is that SAR is not about the Set Format window, but only
> about the Resource --> Assett --> Info --> Resize, or also Timeline
> --> RMB --> Resize Track or, further, the Scale plugin).
>
> I don't quite understand why ffmpeg and CinGG confuse the definitions
> of PAR and SAR. Maybe for simplicity of code? In fact, the CinGG
> workflow is not difficult: we choose the project properties, including
> the frame size with the "Aspect ratio" option of the Set Format window
> (which is tied to Width x Height). Then, depending on the sources, we
> can change W and H, using W Ratio and H Ratio to perform the
> calculations automatically. All without the need to recall the
> concepts of SAR, PAR and DAR. If we then consider that anamorphic
> pixels affect only a very small minority of cases, not putting the
> concept of PAR serves to consider W/H Ratio as just a simple
> multiplicative factor between the initial and project frame sizes.
>
> Does this explanation sound correct to you? I would appreciate your
> opinions, because I would like to change the manual.
> --
> Cin mailing list
> Cin at lists.cinelerra-gg.org
> https://lists.cinelerra-gg.org/mailman/listinfo/cin
>
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