DNG Compression options
Posted: Wed Apr 24, 2013 3:19 pmI've been looking at various compression options for raw video. I've been compressing files, after I've finished grading them, using Adobe's DNG compression converter. Unfortunately Resolve doesn't seem to like these files very much... but that'll probably change with Resolve 10. Naturally I'd prefer a cheap but effective solution.
On a similar note for the more geeky among us... what about creating a new codec that effectively uses three/four H.264 streams, the raw data being divided between them ? Major limitations impeding such a development are the lack of 12-bit 264 implementations (could possibly use a 4:4:4 implementation and perhaps either average the green channel or add an additional channel).
My understanding of raw is that it's effectively RGB with an additional green channel, with no corrections applied and 12bit precision per channel. A potential starting point could be the open source libx264 project.
If I'm wrong about something or my understanding is flawed please educate
.
-edit- It appears Xilinx makes an H.264 4:4:4 12 bit decoder that can operate at 100mbit/sec (which implies it makes a similar encoder : http://www.xilinx.com/products/intellec ... DEC-HP.htm)
-edit2- scratch the above, dcraw is open source and provides a convenient method for dng data extraction. H.264 is very efficient at encoding greyscale (only luma channel is used).
-edit3- dcraw set to raw output generates an RGB 16-bit per channel PPM (20MB) file from a DNG file (4MB) which ImageMagick then splits into three PPM files, each representing one of the three RGB channels. The files are then handed to three separate H.264 encoders which each generate a file (R,G,B).
On a similar note for the more geeky among us... what about creating a new codec that effectively uses three/four H.264 streams, the raw data being divided between them ? Major limitations impeding such a development are the lack of 12-bit 264 implementations (could possibly use a 4:4:4 implementation and perhaps either average the green channel or add an additional channel).
My understanding of raw is that it's effectively RGB with an additional green channel, with no corrections applied and 12bit precision per channel. A potential starting point could be the open source libx264 project.
If I'm wrong about something or my understanding is flawed please educate
.-edit- It appears Xilinx makes an H.264 4:4:4 12 bit decoder that can operate at 100mbit/sec (which implies it makes a similar encoder : http://www.xilinx.com/products/intellec ... DEC-HP.htm)
-edit2- scratch the above, dcraw is open source and provides a convenient method for dng data extraction. H.264 is very efficient at encoding greyscale (only luma channel is used).
-edit3- dcraw set to raw output generates an RGB 16-bit per channel PPM (20MB) file from a DNG file (4MB) which ImageMagick then splits into three PPM files, each representing one of the three RGB channels. The files are then handed to three separate H.264 encoders which each generate a file (R,G,B).