16×9 to 15×9 to DIGIBETA?

[Andy Mees]

stay with PAL CCIR 601

[Vedat Kiyici]

Hmm. This setting crops top and bottom. Shouldn’t I crop the sides?

[Andy Mees]

Thats odd , it works just fine here. I just did a quick test and got exactly what I expected … an anamorphically stretched 15:9 edge cropped 4:3 video (which when shown on a 4:3 TV in its correct aspect would display in its full raster glory with shallow letterbox bars at top and bottom)

What are you seeing there? What settings is your source video reporting in Compressor (look in the A/V Atrributes tab in the Inspector) … and exactly what settings are you using for the target?

[Vedat Kiyici]

Hi Andy here’s my input video specs:

Encoded Bounds: 720×576
Display Bounds: 768×576
Pixel Aspect Ratio: PAL CCIR 601
Native field dominance: Top first
Frame Rate: 25

And this is what the compressor is doing:

Format: QT
Width: 720
Height: 576
Pixel aspect ratio: PAL CCIR 601
Crop to: Center crop for 1.66:1
(L: 0, T: 56, R: 0, B: 56)
Padding: None
Frame rate: 25
Frame Controls: Off
Codec Type: Uncompressed 10-bit 4:2:2
Multi-pass: Off, frame reorder: Off
Pixel depth: 24

I think I know what’s going on here now. My input video’s pixel aspect ratio should be saying PAL CCIR 601(16×9)
How could I change that? I can’t see how to set that while digitizing.
What’s the correct cropping values for left and right?
If I input the correct crop values would I essentially achieve the same results?

cheers for all the help

[Andy Mees]

Apologies Vedat, I was using a true 16:9 source hence the different results … with a 16:9 Anamorphic source I see what you’re seeing too.

So, for a 16:9 Anamorphic source the easiest way to figure out the necessary crop is by doing some quick sums. As 720 pixels is the encoded source width, and as that equates to 16 units as per the ratio, then 1 unit is 45 pixels (720/16=45). As you’re looking to create a 15:9 Anamorphic target then you need to reduce your 16:9 Anamorphic source by one of those units of width ie by 45 pixels. That being the case, set the Source Inset (Cropping) to Custom, and then manually enter a Left crop value of 22 and a Right crop value of 23 (or visa versa).

See if that works for you.
Best
Andy

[Vedat Kiyici]

No need for apologies. 🙂 Thanks for the information.
I did a test by exporting the clip from FCP as 16X9 and then cropping it. The result was cropping by 31 on each side.
I also did it the way you suggested. Now, I don’t know which way to go since I don’t have a way of monitoring 15×9. I suppose I could make them 16×9 by adding bars and see which one looks closer to original.

Cheers

[Vedat Kiyici]

OK, so here’s my test results:
I exported both 720×576 movies (the one that’s 45 cropped and the one that’s 62 cropped) as 960x576px size movies. (My calculation of 1024px=16 ==> 15=960px)
And then I exported these as 1024×576 by preserving aspect ratio by letterboxing.
The result: The movie that’s cropped 31 on each side looked like it had the right aspect compared to the original movie that’s exported as 1024×576
In saying that there’s quite a bit of degradation in pixel quality and movement after one pass of cropping. The movie looks better if it’s converted to 1024×576 and then cropped.
Does this make sense?

[Andy Mees]

Vedat , it’s all really just the same thing but getting there by different routes.

You’re taking your encoded 720 source and stretching it out to its true display aspect of 1024 … thats a stretch by a factor of 1.422. If you take my 45 pixel crop of the encoded original and stretch it out by the same factor and that comes to 64 … which is exactly the same as what you have there (1024-960 = 64).

So how you chose to arrive at your 15:9 Anamorphic result is entirely up to you. If to your eye, one method seems to produce visibly cleaner results, then it would seem logical that you go with that one. Either way you’re ending up 15:9 which hopefully means you’re happy 🙂

Best
Andy

[Vedat Kiyici]

Makes sense..:)
Thanks a lot Andy
cheers

Vedat