On 02/09/17 21:54, Peter 'p2' De Schrijver wrote:
On 2017-06-27 19:02:39 (+0300), Peter 'p2' De Schrijver <p...@psychaos.be>
wrote:
On 2017-06-27 14:01:25 (+0200), Wouter Verhelst <w...@uter.be> wrote:
On Tue, Jun 27, 2017 at 11:43:55AM +0000, Holger Levsen wrote:
On Tue, Jun 27, 2017 at 01:26:37PM +0200, Wouter Verhelst wrote:
Right, but I doubt we'll ever want to do more than 1080p (if even that),
I used to say the same about DV ("thats all we need") but after having seen
several
cccongress videos in 1080p I must say, higher resolution *is* better.
Both for videos with many small details as well as for "boring videos" where you
only see the speaker???
So I can imagine doing DebConf videos in 4k by now :)
Oh, yeah, sure. I can *imagine*, that's not the problem. Perhaps I
should clarify:
- I doubt voctomix can deal with 4K on today's hardware;
Nageru might, although I should still try it on a more modern GPU (it runs
out of VRAM on my ancient GTX560ti with only 1GB VRAM with a 4k signal, it
does 1080p just fine)
- Most people will not want to download a one-hour 2160p stream (which will be
around 35G if done right) if a 1080p one (about 5G) will suffice;
unlimited broadband internet exists for a reason :)
- While 4K screens do exist, I don't know how many DDs have such screens today
(as opposed to FullHD ones);
4K screens can be had for 300 euro now..
(https://tweakers.net/pricewatch/499457/aoc-u2879vf-zwart.html)
Peter.
_______________________________________________
Of cause this is a presentation / talk we are refering to here - to be
quite honest there is very little point in streaming (or recording) at
anything higher resolution and quality than the "slides" that we capture.
Presently we are able to capture slides, up/downscaled to 720p and audio.
Video from our cameras is also at 1080p, of cause if you want to go any
higher then you need more bandwidth between the cameras and the video
mixer than can be achieved over a single SDI link (and the camera only
has the one output).
Please remember that we are dealing with near raw video into the mixing
PC (regardless of what software it is running) each camera input comes
in over SDI, whilst the slide capture is carried over USB2 and then
ethernet as MJPEG IIRC).
We then encode the output of our 'live vision mix' for the streams and
separately transcode for recordings (after review).
Streaming can only have a single pass encode process (it is live
afterall so we don't know what is comming up next - this has a massive
baring on encoding). We can, however, take multiple passes for the
recordings; this means that the recorded video can be either a much
higher quality or much smaller file size than the stream for any given
bit-rate as the entropy reduction can be much better.
And that brings me to my final point in this reply - bandwidth. We
attempt to provide streams out of a debconf for (currently) 3
presentations at once. Each presentation has 2 live streams - one at a
low bandwidth and the other slightly better. I am not concerned about
the distribution networks ability to handle these 6 streams for multiple
viewers, more the ability to ensure that we are able to get these
streams out of the venue alongside the rest of the conference traffic
(remember this is a different venue each year, and on a network that
that we don't get to stress until the first day!). With that in mind I
really must stress that we endeavor to provide a reliable live stream
that is good enough and fit for purpose over one of higher resolution.
Instead of going to ever higher and higher resolution (and frame rate)
perhaps we should be concentrating on improving the quality of the video
we capture?
As a team we are working to improve the recordings that we make. This
includes, but is not limited to, improvements in: sound, "slide
capture", review process, infrastructure setup, operator training,
encoding and storage. All of which will have a bigger impact on the
quality of recordings before an increase in resolution.
Frankly being able to get uniform sound and lighting from each talk (and
across each talk room) in a consistent manor will make a much bigger
impact...
/Andy
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