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Comment by netrus | Hacker News Reader

I am a huge fan of Google Hangouts, however I am pretty sure my current bottleneck is the upload speed of the people talking with me ... how realistic is it to upload HD video content in real time? [I am on all kind of European DSL connections, most of the time].

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For a lot of people there is going to be an encode (CPU) bottleneck as well. From trying to do webcasting a while ago, I can tell you that encoding HD video in realtime on last years PCs was a major problem.

Then again, it takes this kind of thing to push hardware makers and ISPs forward. If a lot of people want to use google hangouts with HD, it will create a call for internet connections with fast upload speeds (rather than a bias towards download as we see now).

Were you webcasting in 1080p? This only supports 720p, which will be substantially less intensive. I think my phone can encode 720p in real-time. I'm pretty sure a mid-range laptop from the last couple years can do 720p at a reasonable bitrate.

Your phone has a dedicated h264 hardware encoder. Most new computers do as well these days, but not the older ones that actually need it.

Yep. Even 2 year old machines (especially laptops) are unsuited. We have recently been testing Hangouts, Vidyo, Bluejeans, Polycom, Skype, Fuzebox.... and it was a lot of fun trying to diagnose degradation of user experience. Almost never was it network-related (except in cases with 8-10++ endpoints). It's much more common to be CPU-constrained than anything else.

I'd like to plug the logitech c920 webcam that not only has beautiful optics and a terrific auto-focus, wide viewing angle, and dual microphones, but also does the transcoding onboard.

When this was discussed on WebRTC mailing lists, it turned that basically no video-confercing software uses these encoders as a) they're not tuned for real-time usage, and b) often the software has no access to the hardware anyway.

I've noticed the biggest determinate in quality is actually packet loss from wireless connections. Reduce that with a wired connection and it stays very smooth. Also people prioritize clear audio way more than video. The real time part is what makes it difficult.

If you hadn't seen it already, this is super useful: http://apenwarr.ca/log/?m=201304

Bitrate and resolution of a video encoding are two independent variables. I can encode 4K video at 50kbs or a 480p stream at 10mbs. That 4K stream is going to look like crap, but I can do it.

They may not bump up the bitrate exactly proportionately to the increase in resolution, so the effect may not be as pronounced as you think.

If you have enough upload bandwidth to send HD and they have enough download bandwidth to receive HD, at least they'll be able to see you in HD.

As for if they have enough bandwidth for HD, there's only one way to find out :)

1 mbit 1080p could work for many people. It's not beautiful, but it will be more or less sharp (though blocky).

At that data rate, you would be almost certainly better off encoding 1/4 the pixels and letting the recipient's machines upscale.

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