-
10 bit vs 8 bit – detail
I originally posted this in the Final Cut forum, but no response so I’ll try it here.
Here’s the setup. I’m using a Blackmagic HD Extreme card, Sony HVR 25 deck, Convergent HD Connect-MI. My signal flow is as follows: HDMI out of the deck to the Convergent box, SDI out of the Convergent to the Blackmagic SDI in. The source tape is HDV, a well-lit scene – talking head.
I set up a 10-bit sequence and captured the same short clip as 8-bit and 10-bit. Drop them in the sequence, did a split screen and what I’m seeing confuses me. The 8-bit side looks more detailed. The pores in his face, edges, and highlights all appear a bit crisper in 8 bit.
I would have thought the 10-bit clip would have shown more detail. Details are not missing in 10-bit, they just appear sharper in 8-bit. I have searched around and haven’t really seen this detail difference explained. Is there some other benefit to the 10-bit image that I’m not seeing right off? I know it would be helpful if I were going to composite images to be in 10 bit.
By the way, the Convergent box is super. I did split screens comparing SDI, Component, and firewire of of the same clip. The SDI is far better.Thanks,
Dan Sparks
Tricom Video
-
3 Replies
-
Hi Dan,
I believe the HDMI output of the deck is 8-bit so it makes sense to capture at 8-bit. You’re not going to capture a better image by choosing a 10-bit easy setup as the original 8-bit signal doesn’t change when you capture to a 10-bit timeline. Incidentally, capturing directly from the deck using an Intensity card should lead to the same sharp results as using the DeckLink card plus converter.
Thanks for posting your observations!
Regards,
Luke Maslen
Blackmagic Design -
Thanks for clearing that up for me, Luke. If the output of the HVR M25U is 8-bit, I guess I would have thought capturing at 10- bit would have looked the same and not less detailed than capturing at 8-bit. I’ll capture at 8-bit from now on.The Intensity sounds interesting, but I am also using a Betacam SP deck in my system and the HD Extreme card handles that quite well. I don’t know if there would be any benefit going to the Intensity compared to the HD Extreme and Convergent combo I’m using now. Can you think of a reason to change to the Intensity over the Convergent for when I capture from the HVR-M25U? Besides a sale for Blackmagic 😉
Dan Sparks
Tricom Video
-
Hi Dan,
You don’t need the Intensity card in addition to your existing setup and I just mentioned it for anyone else reading this thread who needed to connect to the Sony HDV deck but doesn’t need to connect to analog or SDI decks.
I would also have expected the 10-bit SDI capture to look the same as the 8-bit SDI capture but we don’t have the Convergent box so I can’t test that at the moment.
Regards,
Luke Maslen
Blackmagic Design
Reply to this Discussion! Login or Sign Up