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Comment by nik736 | Hacker News Reader

Anyone knows if video transcoding on GPUs (with FFMPEG) is viable nowadays? If yes, what are the gains?

They have chips dedicated to video encoding/decoding with the latest cards doing h265. Nvidia has an ffmpeg patch here https://developer.nvidia.com/ffmpeg

This depends on if you're doing live transcoding or VOD transcoding.

I work with live transcode, and it can be beneficial to run on g2 instances. Running c4.4xlarge I can transcode a good number of 1080@30 in with 1080/720/480/360/240@30 out. With a proper g2 instance I can transcode more simultaneously.

So cost efficiency really depends on sustained traffic levels. I scale out currently using haproxy and custom code that monitors my pool and scales appropriately. But I monitor sustained traffic levels to know when it makes financial sense to scale up.

If your main concern is transcode speed, CPU is likely sufficient -- I am unable to transcode faster than real time with live transcode.

> I am unable to transcode faster than real time with live transcode

Well, yeah. Maybe quantum computing will change that one day!

What is it you're working on? Colour me intrigued.

I'm not sure if you're kidding or not, but just in case: it is desirable to be able to encode faster than real time (ie: 1 hour of media takes less than 1 hour of time to transcode) so you have leftover processing cycles to do other work.

I know I know aye, the way I read initially amused me for a moment before my brain clicked into gear :)

This is true. But real time encode is essentially what you need to do with live video instead of VOD transcode. You have other processes doing the other necessary work during the transcode.

All in all, I look for somewhere around 0.25s to complete the rest of the work and deliver the segment to CDN.

I'm doing live video ingestion. Transcode to DASH/HLS at 5 different qualities + alternate audio/subtitles where provided.

Decoding is good but hw encoding usually has very bad quality/size ratio compared to best software encoders.

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