3 ms·

Not in our experience -- 4K and VR encoding is pretty hard. We uploaded the same video to YouTube (4K Sintel) and counting from the end of the upload, it took 4

Not in our experience -- 4K and VR encoding is pretty hard. We uploaded the same video to YouTube (4K Sintel) and counting from the end of the upload, it took 417 minutes before it was available to play in 4K VP9, and 36.5 minutes before it was available to play in 4K H.264. (ExCamera took 0.5-2.5 minutes by the same metric, i.e. 6-30x faster than real-time.) You can certainly do "ready-as-soon-as-uploaded" encoding if the resolution is small, upload bandwidth is bad, and the codec is simple, but as networks get faster, resolutions bigger, and video encoders more complex, it gets more difficult. Even a real-time hardware encoder isn't enough for the target use-case here, where the user already has the video in the cloud and wants to apply a transformation (like an edit or filter) and then re-encode the results. ExCamera is trying to make that as interactive/quick as possible. "Real-time" on an hourlong video would still mean waiting like an hour for each operation.

chrisseaton 9y ago
But you weren't paying for this as a service were you? You don't know that YouTube didn't put you in some queue and you don't know how long YouTube actually took to encode it, or how quickly they would be able to encode it if they wanted to? Or am I misunderstanding you?
- keithwinstein 9y ago
  We haven't tried a paid service, although my sense is that YouTube does represent the best-of-breed in commercially available parallel transcoding (free as it is to users). I'd encourage you to try it with a paid service and see where the time-to-finished 4K output shakes out. I'd be surprised if it's better but eager to learn either way. ExCamera is doing it at 6x-30x real time (which is important if you want to make a cloud video editor); I don't think you can buy that commercially today. Ultimately, YouTube uses chunks of 128 frames each because it's too expensive to put key frames much more frequently than that, and other transcoding services will face a similar limitation. ExCamera's purely functional encoder lets it use chunks smaller than the interval between key frames, so the effective degree of parallelism can be a lot higher. (Obviously there's a lot of overhead from using a software codec -- we think hardware codecs should support a "save/restore state" interface too. I think we do have to prototype first in software to demonstrate the benefits before hardware people will take us seriously.)
mynewtb 9y ago
YouTube is trying to satisfy its users as cheaply as possible. You cannot use it as a benchmark for state-of-the-art transcoding services (for which you would need to pay a reasonable fee)
sitkack 9y ago
Youtubes actual reencoding rate is faster than realtime. This is only a balanced comparison in what is available, not in efficiencies.
spyder 9y ago
You can live stream in 4K on YouTube and it's transcoded to multiple bitrates: https://www.youtube.com/watch?v=ZMQFsNqGavU https://www.youtube.com/watch?v=ZMQFsNqGavU

chrisseaton 9y ago

But you weren't paying for this as a service were you? You don't know that YouTube didn't put you in some queue and you don't know how long YouTube actually took to encode it, or how quickly they would be able to encode it if they wanted to? Or am I misunderstanding you?

keithwinstein 9y ago
We haven't tried a paid service, although my sense is that YouTube does represent the best-of-breed in commercially available parallel transcoding (free as it is to users). I'd encourage you to try it with a paid service and see where the time-to-finished 4K output shakes out. I'd be surprised if it's better but eager to learn either way. ExCamera is doing it at 6x-30x real time (which is important if you want to make a cloud video editor); I don't think you can buy that commercially today. Ultimately, YouTube uses chunks of 128 frames each because it's too expensive to put key frames much more frequently than that, and other transcoding services will face a similar limitation. ExCamera's purely functional encoder lets it use chunks smaller than the interval between key frames, so the effective degree of parallelism can be a lot higher. (Obviously there's a lot of overhead from using a software codec -- we think hardware codecs should support a "save/restore state" interface too. I think we do have to prototype first in software to demonstrate the benefits before hardware people will take us seriously.)

mynewtb 9y ago

YouTube is trying to satisfy its users as cheaply as possible. You cannot use it as a benchmark for state-of-the-art transcoding services (for which you would need to pay a reasonable fee)

sitkack 9y ago

Youtubes actual reencoding rate is faster than realtime. This is only a balanced comparison in what is available, not in efficiencies.

spyder 9y ago

You can live stream in 4K on YouTube and it's transcoded to multiple bitrates: https://www.youtube.com/watch?v=ZMQFsNqGavU https://www.youtube.com/watch?v=ZMQFsNqGavU