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Messages - akshayverma1

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I was getting higher bitrates with the previous port. But with the new port's CBR there's very few artifacts. Noise reduction works so well :) VBR with Qscale -16 is almost as good as CBR at 20x. Can CBR be pushed to more than 20x? Also, which is better, jpeg or 422?

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Archived porting threads / Re: First 7D alpha released!
« on: November 02, 2012, 09:11:26 AM »
Cropmarks will always be stretched to cover the 3:2 image area (even on 4:3 screens). So, the same files can be used on all cameras.

Yes, but scaling was causing aliasing with 4:3 screens. Isn't it best to have pixel perfect, unscaled marks? :)

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Archived porting threads / Re: First 7D alpha released!
« on: November 02, 2012, 08:11:32 AM »
I made some cropmarks for the 7D. These are for 640*480 since the screen is 4:3, unlike the 720*480 on the 3:2 screens.
The actual size is 640*427 because the rest of the pixels in height are taken up by the information bar at the bottom, effectively leaving us with a 3:2 usable area.

1) Cinemascope 2.35:1 with translucent 16:9 borders, rule of thirds grid and action safe lines (very thin and non-interfering)
http://dl.dropbox.com/u/48224378/CineSco1.bmp


2) 16:9 with translucent border, 2.35:1 lines in black and action safe. (No rule of thirds grid on this one because the default camera grid works for this)
http://dl.dropbox.com/u/48224378/CineSco%26HD.bmp



In the crop marks guide it was written that 1 px lines cause aliasing on 4:3 screen and should be avoided. I figured it was due to scaling from 720 px to 640 px. In these crop marks, the action safe lines are 1px and don't cause any aliasing  :)

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Thanks for the tests ;D what bitrates were you averaging and peaking at for those jpegs?  And I assume those were single frames taken from a video right?

Yes, those are single frames taken from video. Average bitrate for the newsprint was about 150. Peak was 170. For the tree, average was 210, and peak was 260.

I did some high ISO tests with well lit trees last night and got some amazing bitrates - 290 peak and 260 average. It's 35 seconds and 1.04GB. :)

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That's some really good sharpening work there. What did you use to sharpen these up? I can't believe there's practically no moire on these patterns. Did you use  an anti-aliasing filter such as the VAF7D?

I sharpened these with After Effects' built in unsharp mask at 200% (wanted to over sharpen a bit), radius: 1px, threshold:0.
Didn't use any anti-aliasing. I guess it's not there because the details are rather large (the pictures aren't cropped). Ink droplets on a newsprint are quite visible.

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I did some tests with the All-I port.

These are jpegs at quality setting 10.
1080p at 25FPS
Bitrate: CBR 20x
1/250s, f/5.6, ISO 160
18-135mm lens at 135mm

1) Newspaper closeup: unsharpened


Sharpened:


2) Tree: unsharpened


Sharpened:


Compression artifacts still show up occasionally. All-I is improving the quality but if the bitrate could be constant there would be a major improvement.

Thanks a ton for all the hard work g3gg0!

@P337: Yes! I agree anything lower than f/8 would soften the footage, but a still image taken at the same aperture isn't that soft. I think it's because of the line skipping, as ilguercio pointed out. This time I shot at f/5.6 (which I think is the sharpest for this camera, or even f/6.3) and it's still not sharp.

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Thanks for the answer, ilguercio.

I shot some more footage, this time water coming from a tap with lots of fast-moving bubbles. The difference is clear between bitrates lower than 1x, and 1x. There's a lot of compression artifacts at lower bitrates.

I also shot a ceiling fan at 1/500s. Again, there is only minimal difference between 1x and 20x. I have tried applying an LUT (shot in cinestyle), color grading, denoising, and over-sharpening. 20x is only minimally better; it still has some artifacts on the moving blades. Is this because it's VBR?

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I'm using a SanDisk Extreme 8GB 60mbps card. I just shot some trees.

ISO 160
Shutter 1/250
Aperture f/11
Flush rate: 4
CBR 20.0x
Focus peaking, magic zoom, histogram, waveform and bitrate display were ON
Audio OFF

I recorded 1 minute, 42 seconds of handheld footage. Recording was stopped by me (it would keep recording for the whole 4GB). The file size is 2.38GB.

As g3gg0 rightly said, it's actually VBR. I got a maximum bitrate of 218 while the average was around 170. Although I focused it pin-sharp, the footage is blurry as is all 7D footage. Visually it looks just like ordinary 1x BR to me.

Could anyone please guide me about doing a better comparison?

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