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@loonietoque
Created January 31, 2024 19:51
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Ultrawide on Twitch

Ultrawide Streaming Notes

When I am speaking on "ultrawide", I am usually referring to the common aspect ratio stated as "21:9".

I argue there is a case for content creation at 21:9 resolutions. Primarily,

  • Smartphones are a very common viewing device, and are ever-increasing in lengthier aspect ratios. Many creators already use 18:9 instead of 16:9 for this reason.
  • For desktops, folks are very rarely watching in fullscreen mode anyways

That said, I straight up just don't recommend creating content at 32:9.

There's a reason that when Samsung Odyssey is sponsoring creators with these monitors, you never actually see them playing on it at the native aspect ratio — almost no one is going to be able to see what they're doing!

Optional Preamble

I want to note the difference between quality and resolution when it comes to compressed video.

A resolution is specified in pixels, while quality can impact the "blockiness" or "blurriness" of the video. It is entirely possible to have a 4K (3840x2160) high-resolution video that looks bad due to bad quality, resulting in visual blocking, especially in high motion footage.

One of the primary factors in quality is bitrate. On Twitch, we have a very limited bitrate we're allowed to send. Similarly, on YouTube, while we can upload just about anything, their different "resolution" options also somewhat determine the bitrate they'll deliver. Twitch starts to offer significantly better bitrate above their 1440p option.

Twitch

Twitch treats resolution options by the vertical component primarily.

For example, ultrawide "720p" on Twitch is 1720x720.

Recommendations — 3440x1440

If you are on a 3440x1440 display, stream at 1720x720. This is a perfect 4-to-1 pixel downscale, looks clean, and is good total pixel count for the bitrate Twitch allows.

People often consider Twitch's bitrate limit as not enough for 16:9 1080p60 for high-contrast and/or high-motion games, and recommend 936p or even 720p. Ultrawide 720p is more pixels than 16:9 720p, and a bit less than 16:9 936p.

Pixel counts:

  • 21:9 1080p: 2.76M
  • 16:9 1080p: 2.07M
  • 16:9 936p: 1.56M
  • 21:9 810p: 1.56M
  • 21:9 720p: 1.24M
  • 16:9 720p: 0.92M

Recommendations — 2560x1080

Note: This resolution is not 21:9 either, but also not 21.5:9, but a unique 64:27 (or 21.33:9 if you prefer)

This is a tricky resolution. It's too many pixels to send straight to Twitch for the bitrate limit, and the first whole-number downscale is 1280x540, which is really sacrificing a lot of resolution.

I therefore recommend 1920x810. This is basically a 16:9 1920p that's been chopped a bit vertically, and both horizontal/vertical dimensions scale to an exact number nicely.

This resolution also has the benefit of perfectly matching YouTube's "1080p", so you'll get a 1080p option on YouTube without any scaling artifacts.

The pixel count also matches the often-recommend 16:9 936p for Twitch, so it's a good use of the bitrate.

Pixel counts:

  • 21:9 1080p: 2.76M
  • 16:9 1080p: 2.07M
  • 16:9 936p: 1.56M
  • 21:9 810p: 1.56M
  • 21:9 720p: 1.24M
  • 16:9 720p: 0.92M

YouTube

YouTube treats resolution options by the horizontal component of a matching 16:9 resolution primarily. For example, 1080p actually corresponds to any aspect ratio where the horizontal component is 1920px (the vertical amount does not matter).

Recommendations — 3440x1440

Unfortunately, no clean downscale of 3440x1440 fits nicely into YouTube's sizing. There is one nice benefit though.

For example, ultrawide options scaled from 3440x1440 on YouTube are...

  • "480p": 854x358
  • "720p": 1280x536
  • "1080p": 1920x804
  • "1440p": 2560x1072
  • "4k": 3440x1440

As you can see above, YouTube will currently accept a 3440x1440 upload and directly serve this resolution as the "4k" option, despite neither dimension matching true 4k.

I therefore strongly recommend uploading the native 3440x1440 resolution without any scaling, where possible.

Recommendations — 2560x1080

This resolution is perfect for YouTube content!

For example, the quality options on YouTube will correspond to...

  • "1080p": 1920x810
  • "1440p": 2560x1080

"1440p" (the first "good bitrate" option) perfectly matches the native resolution, and "1080p" matches my streaming recommendation above.

I recommend uploading at either the native 2560x1080 (for a high-quality "1440p" option to be available) or 1920x810 (for a good-enough "1080p" option that doesn't get further scaled by YouTube)

Recording & Streaming Simultaneously

You may want to record and stream at the same time so that you can have higher-quality files available to make long-form or short-form content for YouTube, TikTok, etc.

While recording or streaming (or doing both at the same resolution) has a relatively low performance impact these days, recording and streaming at different resolutions imposes a large performance hit in OBS.

Recommendations — 3440x1440

This resolution is hard to accommodate, frankly.

The recommended stream resolution is 1720x720. If this was uploaded directly to YouTube, the max quality option would be "720p", and it will have been downscaled to 1280x536. Ouch.

Option 1 - Low Performance Impact, mediocre results

This prioritises stream quality, while offering clean-but-low-resolution recording.

  • Stream at 1720x720
  • Record (CQF, high bitrate) also at 1720x720
  • In editing, upscale to 3440x1440

Upscaling back to native res definitely won't look the best, but it'll trick YouTube into serving the high-bitrate/-quality "4k" (and below) options.

It's not great, but it works.

Option 2 - High Performance Impact, perfect results

  • Stream at 1720x720
  • Record (CQF, high bitrate) also at 3440x1440

Please note that recording at 3440x1440 is actually a lot of pixels, and in some systems gets into the area of encoder overload.

This will give best-possible stream and recording quality, but at a noticeable performance cost.

Notable Takeaways

2560x1080

  • Uncommon "lower" resolution "21:9"
  • Fantastic for YouTube without additional scaling

3440x1440

  • Much more common "21:9"
  • More GPU stress in games (many pixels)
  • Scales cleanly (half res) for Twitch

FAQ

Should I just record with black bars in a 16:9 container?

  • No. This permanently makes your video smaller on displays that could otherwise nicely fit the wider video, and offers no benefit to those that cannot. YouTube strictly recommends against adding black bars for this reason.
  • If you must stream or record in 16:9, I recommend using the "Scaling/Aspect Ratio" filter built in to OBS, set to "16:9" for Resolution, and checking the "Undistort center of image when scaling from ultrawide" option.
    • This squishes the edges more so that the center of the view isn't squished.
    • UI Elements, text, etc. near the edges will become harder to discern, but center content will remain "normal".

What about black bars when streaming, where I can put alerts, info, etc. instead?

  • Aside from the same reasons to not do so on YouTube, I found it was mostly a waste of space and bitrate capacity
  • Use your extra width for alerts, since that's where the strength is. Not top/bottom bars.
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