4 ms·

Well, we have this evidence so far, on a phone that has no active cooling: https://twitter.com/tldtoday/status/1326610187529023488 https://twitter.com/tldtoday/

by raydev 6y ago

Well, we have this evidence so far, on a phone that has no active cooling: https://twitter.com/tldtoday/status/1326610187529023488 https://twitter.com/tldtoday/status/1326610187529023488

refulgentis 6y ago
that's comparing a hardware encoder to a software one, unfortunately, as the replies note. it's unfortunately drowned out by the cpu throttling scandal on google, but, its well-known in ar dev (and if you get to talk to an apple engineer away from stage lights at wwdc) that you have to proactively choose to tune performance, or you'll get killed after a minute or two due to thermal throttling.
- chrismorgan 6y ago
  This raises the question of just why the Mac is doing software rendering—I think the hardware it’s running on should have two compatible hardware encoders, that on the CPU and that on the GPU. Is the software being used incapable of using hardware encoding? Does it default to software rendering because of its higher quality per bit? Was it configured to use software encoding (whether ignorantly or deliberately)?
  - imtringued 6y ago
    Video encoding is generally done on CPUs because they can run more complicated video encoding algorithms with multiple passes. This generally results in smaller video files with the same quality. As you increase the compute insensitivity of the video encoder you get diminishing returns. 30% lower bitrate might need 10x as much CPU time. That tweet says more about the type of encoder and chosen encoder settings than anything about the hardware. Imagine going on a hike and climbing an exponential slope like 2^x. You go up to 2^4 and then go down again and repeat this three times so you have hiked 12km (43) in total. Then there is a athlete who is going up to 2^8. He says he has hiked 8km and you laugh at him because of how sweaty he is despite having walked a shorter distance than you. In reality 32^4 (48) is nowhere near 2^8 (256). The athlete put in a lot more effort than you.

by raydev 6y ago

Well, we have this evidence so far, on a phone that has no active cooling: https://twitter.com/tldtoday/status/1326610187529023488 https://twitter.com/tldtoday/status/1326610187529023488

refulgentis 6y ago

that's comparing a hardware encoder to a software one, unfortunately, as the replies note. it's unfortunately drowned out by the cpu throttling scandal on google, but, its well-known in ar dev (and if you get to talk to an apple engineer away from stage lights at wwdc) that you have to proactively choose to tune performance, or you'll get killed after a minute or two due to thermal throttling.

chrismorgan 6y ago
This raises the question of just why the Mac is doing software rendering—I think the hardware it’s running on should have two compatible hardware encoders, that on the CPU and that on the GPU. Is the software being used incapable of using hardware encoding? Does it default to software rendering because of its higher quality per bit? Was it configured to use software encoding (whether ignorantly or deliberately)?
- imtringued 6y ago
  Video encoding is generally done on CPUs because they can run more complicated video encoding algorithms with multiple passes. This generally results in smaller video files with the same quality. As you increase the compute insensitivity of the video encoder you get diminishing returns. 30% lower bitrate might need 10x as much CPU time. That tweet says more about the type of encoder and chosen encoder settings than anything about the hardware. Imagine going on a hike and climbing an exponential slope like 2^x. You go up to 2^4 and then go down again and repeat this three times so you have hiked 12km (43) in total. Then there is a athlete who is going up to 2^8. He says he has hiked 8km and you laugh at him because of how sweaty he is despite having walked a shorter distance than you. In reality 32^4 (48) is nowhere near 2^8 (256). The athlete put in a lot more effort than you.