4 ms·

I was curious about this so I did a little research. > you need to decode and have every frame ready in less than 41 milliseconds, which is shockingly difficul

I was curious about this so I did a little research. > you need to decode and have every frame ready in less than 41 milliseconds, which is shockingly difficult even on high-end hardware There appear to be multiple high-speed JP2K decoders on the market; Comprimato[0] include a calculator for their product and it claims that a $240 GPU from 2016 can decode 4k 4:4:4 at 72fps. > Do I need to mention read speeds and network traffic? If every frame is, say, just 5MB, that is over 960 Megabits per second, saturating a Gigabit link. According to Wikipedia, the DCP standard has a maximum bit rate for picture of 250Mbit/s[1]. My $60 home internet connection could stream that at almost 2x realtime. > When you are calculating audio in real-time for 30 or more speakers, the compute costs add up, potentially into custom hardware / FPGA territory. Dolby offer a software version of Atmos for soundtrack mastering that runs on a Mac Mini[2]. Real-time 128-channel object mixing was possible using consumer-grade hardware as early as EAX 5.0 in 2005[3], but Atmos does not need to be rendered in real time at a cinema, it can be done in advance and then during playback those pre-rendered PCM streams would be used which is a trivial amount of data to handle (under 20Mbit/s for a full 64-speaker array). [0] https://comprimato.com/products/comprimato-jpeg2000/ https://comprimato.com/products/comprimato-jpeg2000/ [1] https://en.wikipedia.org/wiki/Digital_Cinema_Package#Picture_MXF_files https://en.wikipedia.org/wiki/Digital_Cinema_Package#Picture... [2] https://professionalsupport.dolby.com/s/article/What-are-the-current-computer-OS-and-I-O-configurations-for-running-the-Dolby-Atmos-Renderer-on-a-dedicated-Workstation https://professionalsupport.dolby.com/s/article/What-are-the... [3] https://en.wikipedia.org/wiki/Environmental_Audio_Extensions#EAX_5.0 https://en.wikipedia.org/wiki/Environmental_Audio_Extensions...

gjsman-1000 3y ago
> There appear to be multiple high-speed JP2K decoders on the market; Comprimato[0] include a calculator for their product and it claims that a $240 GPU from 2016 can decode 4k 4:4:4 at 72fps. Interesting, that's a lot better. This is my source for my numbers: https://www.fastcompression.com/benchmarks/decoder-benchmarks-j2k.htm https://www.fastcompression.com/benchmarks/decoder-benchmark... A GPU helps for sure, a CPU alone is pretty bad. > According to Wikipedia, the DCP standard has a maximum bit rate for picture of 250Mbit/s.[1] I'm really surprised, I would not have thought that a 4K frame at a theatrical quality level would fit into about 1.3MB. But maybe that's why they chose JPEG 2000. > Dolby offer a software version of Atmos for soundtrack mastering that runs on a Mac Mini[2]. 128-channel object mixing was possible using consumer-grade hardware as early as EAX 5.0 in 2005[3]. That's not quite true because Dolby Atmos came out in 2012, not 2005. As for theatrical hardware, even though I'm not sure why it is so expensive, look at the Dolby CP850. It's a 64-channel object mixer for theaters and it costs about $8,000 (or $18,000, depending on where you shop and who you trust on the subject). As far as I know, EAX is not even a true surround sound encoding technology in the first place, and was a much more primitive system only for video games that is not directly comparable. I suspect part of the cost is all of the outputs, and also because Dolby has been clear that they make their money (patent licensing) on playback equipment, not production equipment. I can't find the specific webpage, but it's no secret in the industry Dolby charges much more on licensing for devices with lots of outputs.

gjsman-1000 3y ago

> There appear to be multiple high-speed JP2K decoders on the market; Comprimato[0] include a calculator for their product and it claims that a $240 GPU from 2016 can decode 4k 4:4:4 at 72fps. Interesting, that's a lot better. This is my source for my numbers: https://www.fastcompression.com/benchmarks/decoder-benchmarks-j2k.htm https://www.fastcompression.com/benchmarks/decoder-benchmark... A GPU helps for sure, a CPU alone is pretty bad. > According to Wikipedia, the DCP standard has a maximum bit rate for picture of 250Mbit/s.[1] I'm really surprised, I would not have thought that a 4K frame at a theatrical quality level would fit into about 1.3MB. But maybe that's why they chose JPEG 2000. > Dolby offer a software version of Atmos for soundtrack mastering that runs on a Mac Mini[2]. 128-channel object mixing was possible using consumer-grade hardware as early as EAX 5.0 in 2005[3]. That's not quite true because Dolby Atmos came out in 2012, not 2005. As for theatrical hardware, even though I'm not sure why it is so expensive, look at the Dolby CP850. It's a 64-channel object mixer for theaters and it costs about $8,000 (or $18,000, depending on where you shop and who you trust on the subject). As far as I know, EAX is not even a true surround sound encoding technology in the first place, and was a much more primitive system only for video games that is not directly comparable. I suspect part of the cost is all of the outputs, and also because Dolby has been clear that they make their money (patent licensing) on playback equipment, not production equipment. I can't find the specific webpage, but it's no secret in the industry Dolby charges much more on licensing for devices with lots of outputs.