Bob vs. Decomb -- The HD tests
Posted: Mon Nov 10, 2014 3:52 am
In a previous discussion, we compared Bob and Decomb from some noisy SD analog footage, and I came to the conclusion that the bobbed footage was visibly noisier and less detailed in the shadows. For the purpose of the discussion, "Bob" means 60p output, and "Decomb" is 30p, using the defaults at RF20.
Using a Belle-Nuit 1080 test chart, I rendered Sony YUV 8-bit 4:2:2 intermediates and handed them to Handbrake. As expected, the chroma subsampling flags triggered from the downsampling to 4:2:0, so what we're interested in is only between 0-16 RGB below. Then we compared them to Project previews at 60p (59.94) and 60i (29.97), using a Difference Mask to isolate noise content.
Both fared well with static images. Decomb was sharper and cleaner on the scopes, but I really couldn't see a difference in the delivery. Bob had more shadow noise, but it was also difficult to detect in a static scene (still image). Here's the decomb 30p noise print.
And here's Bob with a static image.
I predicted that noise would be worse with motion detail, and this was reflected in the tests. Again, Bob fared worse. Here's the Decomb motion noise print.
And here's Bob under motion. This time, I could see a slight difference during fades, which are particularly bad for showing high noise vs. detail.
Using a Belle-Nuit 1080 test chart, I rendered Sony YUV 8-bit 4:2:2 intermediates and handed them to Handbrake. As expected, the chroma subsampling flags triggered from the downsampling to 4:2:0, so what we're interested in is only between 0-16 RGB below. Then we compared them to Project previews at 60p (59.94) and 60i (29.97), using a Difference Mask to isolate noise content.
Both fared well with static images. Decomb was sharper and cleaner on the scopes, but I really couldn't see a difference in the delivery. Bob had more shadow noise, but it was also difficult to detect in a static scene (still image). Here's the decomb 30p noise print.
And here's Bob with a static image.
I predicted that noise would be worse with motion detail, and this was reflected in the tests. Again, Bob fared worse. Here's the Decomb motion noise print.
And here's Bob under motion. This time, I could see a slight difference during fades, which are particularly bad for showing high noise vs. detail.