Difference between internal codec and external recorder

G

Gugulino

Active member
To those, who say that an external recorder is useless with the AF100: Here is the prove that it is not.
The first picture shows the same frame as the second (recorded simultaneously) but the first was recorded over HD-SDI to a Blackmagic UltraStudio 3D. The recording format was DPX.
The second picture was exported from FinalCutPro X as TIFF and represents the internal codec (PH-mode, 25 fps).

1. http://www.gugusoft.com/Bilder/Bild-020163.tiff

2. http://www.gugusoft.com/Bilder/Finale.tiff

If you look at the black jeans of the guitarist, you see only black in the second picture. The first picture, which was recorded over HD-SDI shows much more details in the same area.
 
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Hey Gugulino - thanks for posting, this is interesting. I've been meaning to post my own little test lately, as I've recently been recording to the Hyperdeck 2. Clearly, your two pics are different. I could tell that without even A/Bing them.

So far I've had a different result. I have yet to detect any difference in my footage at all, between recording to SDHC cards, Hyperdeck ProRes, or Hyperdeck uncompressed.

Since we're both using Blackmagic products whose purpose is to record an uncompressed HDSDI signal, it would stand to reason the source of my problem lies elsewhere. Are there any camera settings you're using in terms of your scene file that are unusual? Any idea why I'm seeing no benefit to shooting uncompressed?

My test shots so far have been similar to yours; skin tones, highlights, shadows, etc. And when I toggle between card footage, prores, and uncompressed, I can indeed see that the frames are different, ie. segments of aliasing are slightly different, noise is not identical, etc so I know I am indeed looking at different recordings. The point is, the image itself is essentially identical in terms of shadow detail, sharpness, color, and so on. And when I push the footage to extremes with color correction, they both fall apart in exactly the same way.
 
Gugulino, try running the original MTS file from the card through 5DtoRGB using the "Full Range" luminance setting and compare the resulting file with the DPX.
 
Gugulino said:
If you look at the black jeans of the guitarist, you see only black in the second picture. The first picture, which was recorded over HD-SDI shows much more details in the same area.
Click to expand...

Not what I see. I see the same amount of detail in the guitarist's pants in both. The first one doesn't have a solid black, but the second one is better (darker). The first one looks like the black level is held up and the white level is held down -- looks like 16-235 to me. You can see this especially well from the white shirt front of the left most violinist. In the first picture, she has highlight detail, in the second picture it's blown out and is pure white without detail.

I think what you are looking at is a difference in contrast. I suspect that it's largely due to the two pictures having different black and white points. IOW, you're comparing apples to oranges. Look at them with a waveform monitor -- the differences should show up clearly.
 
I have the Hyperdeck2 so I say this with no bias but the other post above me is right, half of the benefit of the recorder is stuff you don't see as it just doesn't capture more detail, colour or range. It just looks like typical FCPX black and white clipping and not the whole range of 0-255. External capture is still with it for the noise pattern and extra colour resolution but its never night and day on the AF100
 
@jsolterbeck: I did not use a special scene file setting and I don't think that this matters. Perhaps you can't see any difference, because your NLE supports the full range of luminance and does not clip highs and lows as FCP X does.

As suggested by Nate, I used 5DtoRGB to import the MTS-Clip. Here is the result:

http://www.gugusoft.com/Bilder/Bild-017540.tiff

It shows more shadow detail, as the frame grab from the internal codec, imported wit FCP X, but less than the one taken from the external recorder. But the difference is very small. So, in fact, it was only a thing of importing the footage that made the difference in contrast.
I have some footage that was captured only to the SDHC cards. I might them reimport with 5DtoRGB to match the footage that was recorded in DPX format.
 
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