a few technical questions about vr porn

erniescar69

Hey guys, I'm curious how studio's and vr content creators determine what bitrate is best to encode their videos at? Do they aim for the best image quality and don't care about file size or do they try to find a balance between them? Is there a point of diminishing returns in regards to high bitrates? How much does the hardware like camera rigs affect this? The reason I'm asking is I recently noticed a huge difference in bitrates and file sizes for similiar videos from 2 studios that I'll lay out below...

Studio A - video is just under 44 min long, 180 degrees, 4K (4320x2160) version is h264, 60fps, 12,500 kbps and is just under 4 GB. The 5K (5400x2700) version of the same video is h265, 60fps, 62,000 kbps and almost 20 GB. Both are listed for Oculus and Vive hmd's.

Studio B - video is just under 43 min, 180 degrees, 4K (4320x2160) version is h264, 60fps, 29,900 kbps and 9 GB. The 5K (5400x2700) version of the same video is h265, 60fps, 30,000 kbps and just over 9 GB. Both are listed for Oculus and Vive hmd's.

Why is there a 5X increase in bitrate and file size for the 5K version from studio A and not studio B? Correct me if I'm wrong but the pixel density for 5K is not 5X that of 4K so the increase seems crazy to me. Isn't 5K res about double the pixel density of 4K? If so, shouldn't studio A be able to encode the 5K version at 25,000 kbps and still keep the same quality as the 4K version? Also...what kind of magic or sorcery is studio B using to keep the same bitrate and file size between the 4K and 5K versions?

I haven't watched both versions of each of the videos to compare visual quality between them so I honestly can't say if one is better than the other. My shitty bandwidth speeds means I need to be selective in which files I D/L and I just can't justify wasting that much bandwidth for a vrporn/science experiment. I'm just interested in getting peoples thoughts and maybe learning something new.

Thanks!

Rakly3

There's actually a lot of variables that influence the best balance between picture quality and bitrate while making sure the targeted device can actually play it. And you can't, from a technical point, compare .264 directly with .265
The footage itself also influences the complexity needed.

ie you can make a 4K .264 that plays on an iPhone X, and one that doesn't. just by changing 1 of the variables.
Another point is, what is the source-file like? If your sourcefile is RAW fisheye, you CAN preserve more detail.

It's near impossible to explain everything in a forum post. But a good way to start figuring stuff out, imo, is get MediaInfo https://mediaarea.net/en/MediaInfo
You can then simply right click any media file (so also images, music...) and get all the info about it.
Be default MediaInfo opens in Basic view. I personally like Tree view as it shows everything in a clean clear structure.

Start with 'googling' what I highlighted in orange.

fisheye, equirect and youtube cubemap also play a role.

How each studio decides what to use? Probably the hardware and software used + personal bias. You're not gonna find a consensus on which settings are best for scene A or any other scene.