Hacker News Reader

Comment by cbhl | Hacker News Reader

$5.40 to encode a 15-minute video is... a lot. Amazon Elastic Transcoder runs at $0.03/minute, so it would be $0.45 to encode the same 15-minute video.

The value of doing video processing with general-purpose compute is either A) you can adopt new codecs quickly (to save operational costs), or B) you can do processing in batch with older/slower/off-peak compute resources (to save capital costs).

If a company was going to spend $XM on engineers to build a low-latency video processing solution at scale, you'd go for the "remove-a-layer-of-abstraction" of thousands of tiny threads: purpose-built real-time encoding silicon.

View on HN

This really depends on how much you're paying to make that 15 minute video. 15 minutes of video can cost 10 cents or 10 million dollars.

This is about processing video in real time in the cloud. The intro mentions that in the nonparallel case, 1 hr of 4k video can take 30hrs to process. Doing it in <1hr has real benefits.

AFAIK transcode-as-a-service vendors already offer real-time/streaming transcoding, so it's over as soon as you finish uploading the file.

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.

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?

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.)

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)

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

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

Yah I read it and just shook my head as silly...

Reply on news.ycombinator.com