CaptaPraelium
Member
I've typed this up for a few friends lately and as 1440p gaming becomes more popular with time I thought it might make sense to put it somewhere public. This forum seems as good a place as any I could think of, but perhaps I should make a resource/guide, as this is not applicable to windows only.... We'll see where it goes over time.
This is basically a copypaste from a chat room so I tried to keep it brief and simple and avoid jargon. If more details or corrections are needed I will reply or edit it as needed. I just wanted to archive this info somewhere, so that others don't have to guess or work it out the hard way. As always, YMMV, do what you want, do what works for you. This just explains the reasoning and method behind the choice of 864p downscaled streams from 1440p games. Perhaps you'd prefer a different scale or a higher bitrate or whatever, I'm not the boss of you. I'm just explaining some stuff because it's not really well documented online, since most people historically play at 1080p or less. I hope this helps :)
Yeh if you are partnered, it is easy, you just stream at your native resolution and a super high bitrate as high as your upload can handle it... then twitch servers transcode that into different resolutions and rates for the viewers, but for the rest of us, we have to stream at around 6000kbps maximum, because twitch will not transcode, so the viewers have to be able to download >6Mbps to watch that.
But high resolution = more pixels = more bits of data
So the stream will have to either be high bit rate for high resolution, or we must compress it more
And the more we compress, the worse the quality of the picture
But if we reduce the resolution, then we also lose quality
So it is a balancing act :)
This is why it is generally recommended that if you play in 1080p it is best to stream at 720p... Because for 1080p to fit in 6000kbps, there is a lot of compression, and the compression makes the picture look bad especially for lots of movement (such as in FPS games where we are very 'twitchy' in our movement and aim)
If we downscale from 1080p to 720p there is also some quality loss, but the compression required to fit in 6000kbps at 720p is not so high, so the overall result is better
But 720p is 3/4 of 1080p and if we use this same scaling for 1440p, we would have a 1080p stream and we have the same problem as before... but if we scale from 1440p to 720p, that is 1/2 resolution, and the quality loss from that downscale is very bad so now we have a new problem.
So we have to find a new place to balance it... we can downscale a little more than the 3/4 but there is more quality loss, or we can compress more and there is more quality loss. We will always have lower quality than gamers playing at 1080p because we are always trying to fit more pixels from our game in the same bitrate stream....
This is why sometimes you will have problems watching 1440 or ultrawide streams, because sometimes people will just stream a higher bitrate to avoid this problem... but then it creates other problems with watching the stream because it is a fast download and there are lots of places between you and the streamer where that can become a problem so even if your download is fast enough it can still effect you.
So to work it out we can start with this list https://pacoup.com/2011/06/12/list-of-true-169-resolutions/ which shows resolutions at our same aspect ratio, and importantly it shows (highlighted in green) those resolutions which are divisible by 8. It is important to use one of those because of the way h264 encoding works, it breaks down your picture into squares, these blocks of pixels, to figure out how to compress them, and if we don't use one of those resolutions divisible by 8 (divisible by 16 is best in fact - another reason why 720p streaming is better than 1080p) then our encoder has to add some 'empty' pixels onto the side and bottom of our image, which means it has to do extra work and we lose performance for nothing.
So if we just consider those resolutions between 720p and 1080p, we have 792p, 864p, 936p, 1008p ... at 792 the downscale is still too much and looks ugly. At 1008p the compression is too much and looks not good.... So we should choose from one of the two in the middle. At 864p, we now have a downscale which looks OK - every 5x5 square of pixels becomes a 3x3 square of pixels. This gives us more room to do less compression so a moving picture looks best. We can go up to 936p resolution, and our downscale is less, but it is a very uneven ratio (65/100) and now we have to compress our image more and it can look bad especially for fast movement.
Sooooooo that is why 864p is the best streaming resolution for 1440p gaming. (Most of the time! You do you!)
You can use these same concepts to help you choose a downscale from any resolution. Just play the balancing game -
Too much downscaling looks bad because you are losing your picture.
Less downscale is more pixels is more data to compress and more compression looks bad especially with lots of movement.
Increasing bitrate gives you room to play with but can cause problems for viewers.
Sticking to to resolutions divisible by 16 is best but not a must.
This is basically a copypaste from a chat room so I tried to keep it brief and simple and avoid jargon. If more details or corrections are needed I will reply or edit it as needed. I just wanted to archive this info somewhere, so that others don't have to guess or work it out the hard way. As always, YMMV, do what you want, do what works for you. This just explains the reasoning and method behind the choice of 864p downscaled streams from 1440p games. Perhaps you'd prefer a different scale or a higher bitrate or whatever, I'm not the boss of you. I'm just explaining some stuff because it's not really well documented online, since most people historically play at 1080p or less. I hope this helps :)
Yeh if you are partnered, it is easy, you just stream at your native resolution and a super high bitrate as high as your upload can handle it... then twitch servers transcode that into different resolutions and rates for the viewers, but for the rest of us, we have to stream at around 6000kbps maximum, because twitch will not transcode, so the viewers have to be able to download >6Mbps to watch that.
But high resolution = more pixels = more bits of data
So the stream will have to either be high bit rate for high resolution, or we must compress it more
And the more we compress, the worse the quality of the picture
But if we reduce the resolution, then we also lose quality
So it is a balancing act :)
This is why it is generally recommended that if you play in 1080p it is best to stream at 720p... Because for 1080p to fit in 6000kbps, there is a lot of compression, and the compression makes the picture look bad especially for lots of movement (such as in FPS games where we are very 'twitchy' in our movement and aim)
If we downscale from 1080p to 720p there is also some quality loss, but the compression required to fit in 6000kbps at 720p is not so high, so the overall result is better
But 720p is 3/4 of 1080p and if we use this same scaling for 1440p, we would have a 1080p stream and we have the same problem as before... but if we scale from 1440p to 720p, that is 1/2 resolution, and the quality loss from that downscale is very bad so now we have a new problem.
So we have to find a new place to balance it... we can downscale a little more than the 3/4 but there is more quality loss, or we can compress more and there is more quality loss. We will always have lower quality than gamers playing at 1080p because we are always trying to fit more pixels from our game in the same bitrate stream....
This is why sometimes you will have problems watching 1440 or ultrawide streams, because sometimes people will just stream a higher bitrate to avoid this problem... but then it creates other problems with watching the stream because it is a fast download and there are lots of places between you and the streamer where that can become a problem so even if your download is fast enough it can still effect you.
So to work it out we can start with this list https://pacoup.com/2011/06/12/list-of-true-169-resolutions/ which shows resolutions at our same aspect ratio, and importantly it shows (highlighted in green) those resolutions which are divisible by 8. It is important to use one of those because of the way h264 encoding works, it breaks down your picture into squares, these blocks of pixels, to figure out how to compress them, and if we don't use one of those resolutions divisible by 8 (divisible by 16 is best in fact - another reason why 720p streaming is better than 1080p) then our encoder has to add some 'empty' pixels onto the side and bottom of our image, which means it has to do extra work and we lose performance for nothing.
So if we just consider those resolutions between 720p and 1080p, we have 792p, 864p, 936p, 1008p ... at 792 the downscale is still too much and looks ugly. At 1008p the compression is too much and looks not good.... So we should choose from one of the two in the middle. At 864p, we now have a downscale which looks OK - every 5x5 square of pixels becomes a 3x3 square of pixels. This gives us more room to do less compression so a moving picture looks best. We can go up to 936p resolution, and our downscale is less, but it is a very uneven ratio (65/100) and now we have to compress our image more and it can look bad especially for fast movement.
Sooooooo that is why 864p is the best streaming resolution for 1440p gaming. (Most of the time! You do you!)
You can use these same concepts to help you choose a downscale from any resolution. Just play the balancing game -
Too much downscaling looks bad because you are losing your picture.
Less downscale is more pixels is more data to compress and more compression looks bad especially with lots of movement.
Increasing bitrate gives you room to play with but can cause problems for viewers.
Sticking to to resolutions divisible by 16 is best but not a must.