I dont understand why when your watching the even a live stream, like on Twitch, the video quality is very good, but when your trying to video chat with someone else the quality is so much worse. What about the two way video chat makes it so hard to get consistent hd and audio?
In: Technology
1. Upload speed on streaming server is at least 100mbps whereas residential isps rarely give more than 5-10 mbps
2. Cam quality and resolution
3. Pc speed
Edit: but mainly #1
streams can’t take up more bandwidth than is available or they start lagging. if it’s too big it has to be compressed
twitch streams have several advantages for compression: the rendered frames are available before they even hit the player’s screen, have less detail than real life (making the initial image smaller), tend to have many pixels that are identical to their neighbors, and viewers don’t really mind if they recieve the image a fraction of a second later as long as they recieve the audio at the same time
but video chat needs to be as close to live as possible. they already lose time from the camera processing a scene rich in minute detail, and that detail means there are less identical pixels for compression to take advantage of
I think the big difference is a lack of a buffer.
Most video streams (Netflix, Twitch, etc.) actually display a second or so after the data is received. This allows your internet connection to have lots of hiccups (as long as they’re smaller than that second or so) and you’ll never notice. The buffer smooths out the video delivery.
When you’re on a live video chat, you can’t have this buffer, because if you added a 1 second delay onto both sides of the conversation, it would be very difficult to have a conversation. So instead we deal without the buffer (or if there is a buffer, it’s much smaller).
Most home Internet connections are asymmetric – the upload and download speeds are not the same, generally the download speed is much much faster. For Netflix this isn’t a problem because you are only downloading data, but with video chat the video quality is limited by the available upload bandwidth of the person you’re talking to. Twitch is reliant on a good upload speed for the streamer, everyone else is downloading. Twitch needs a 3-6Mbps upload speed to work well. Most consumer Internet connections are 8:1 download to upload speed ratio, so you need an approx 25-50Mbps Internet connection for decent streaming. In addition since the Internet bandwidth may be shared by multiple households, lots of video calls can quickly swamp the upload connection.
Also the cameras on a lot of laptops, are absolutely awful.
One thing not mentioned is that the audio quality is prioritized in a video call. The video being bad quality is far less important than laggy, choppy audio.
So those services will put a minimum amount of resources in producing good audio and the rest of the pipe is for video.
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