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Old 24th August 2020, 22:49   #14  |  Link
benwaggoner
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Join Date: Jan 2006
Location: Portland, OR
Posts: 4,750
Quote:
Originally Posted by Cary Knoop View Post
I would challenge the assertion that not using chroma subsampling would increase the bitrate somewhat for the same perceptual quality.

It would be much more efficient for a CODEC to determine what perceptual compressions to make instead of feeding an already chroma-subsampled source.
I agree. And thanks to Moore's Law, memory requirements become less expensive year-on-year.

Quote:
There are five things, I believe need to change in video processing:

1. More to a float32 code value standard
2. Abandon the difference between full and limited range (no clipping while float 0.0 to 1.0 is always the visible range)
3. No more chroma subsampling (but allow chroma subsampling for legacy sources)
4. No more interlaced sources (but allow interlaced for legacy sources)
5. Allow for multiple framerates in the same source (each frame will have an absolute time duration marker)

This will make life a lot simpler!
1-3 would be a HUGE increase in memory and memory bandwidth requirements. Today 8-bit video is 12 bit/pixel. Going to fully sampled float32 is an 8x increase in memory requirements!

Doing 1080p30 in your proposed would have the same memory requirements as 4Kp60. Even 10-bit HDR would still be 6x more efficient using 4:2:0.

4. Is pretty much accomplished at this point. There is no interlaced happening with resolutiosn beyond 1080i or with HDR. And H.264 was the last codec that really engineered for interlaced efficiency (HEVC doesn't have MBAFF, for example). Interlaced is already a shrinking legacy technology, thank goodness.

5. We've had media formats that just give each frame a duration for ages and ages - supporting a fixed frame rate was itself an innovation that didn't get broadly implemented until about 15 years ago. The real challenge with variable frame rate video is that technologies like HDMI don't handle it gracefully. Over a 60p connection, switching between 24 and 60 has intrinsic judder. Having everything 120 Hz would be a lot easier for NTSC countries. PAL countries mixing 24/25/30/50/60. THe least common multiplier for all standard frame rates is 600. And that's not accouting for the NTSC 29.97/30 timing headache.
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