YouTube in 1080p

Written by D. Eric Franks on 16 November 2009.

Note: YouTube is currently experimenting with this feature and optimizing it accordingly and can't guarantee that videos will always be transcoded into this format.

I shot the shuttle launch this afternoon (STS-129, Atlantis, 2:28 p.m. from ~40 miles away) just for something to upload and play with. The video starts one minute after launch, as the shuttle cleared the trees at my location and ends with SRB-Sep (after the massive solids go out, there isn't much to see anymore). You have to actually (1) click on the "Watch on YouTube" item first, (2) then click on the HD button ("Watch in HD") located in the right hand corner of the player and (3) view it full screen on your (4) 1080p monitor.

Here are the gory details of what I uploaded:

Source: Sony HDR-SR7, 1440x1080, PAR 1.333, 29.97 fps, interlaced
Encode: H.264, MainConcept, 1920x1080, PAR 1:1, roughly 20 Mbps, 29.97, progressive (no audio)
Final file was ~280 MB (for one minute) and took 75 minutes to upload
Basic YouTube encoding took an additional 20ish minutes, SD went live first, followed by two HD encodes
Three clips are available if you peek at the code: SD, HD (720p) and HD (1080p) versions.

The really interesting part, however, is:

YouTube's "old" 720p encoding resulted in files with a data rate of about 2 Mbps, but...
(drum roll please) the new 1080p encoding comes in at roughly 15% higher!
Actual data rates I measured on my sample clip: SD 740 Kbps, HD-720p 1,859 Kbps, HD-1080p 2,177 Kbps.

What does this mean? Well, given that both formats are progressive, which completely negates the data rate equivalence of broadcast 720p60 vs. 1080i60, we'd hope that YouTube would allocate slightly more data bandwidth to the new 1080p streams. Purely in terms of pixels, 1080p on YouTube contains 11% more pixels than 720p. Therefore, YouTube is doing it right and our 1080p pixels are getting the treatment they deserve and maybe a little more. That doesn't mean you should get all excited about 1080p, however.

Broadcast HD television happens in two different formats, 720p and 1080i. 720p60 means 60 full-resolution (progressive) frames of 1280x720 pixels per second, or 55.3 million pixels a second. Compare that with 1080i60, which is 60 half-resolution (interlaced) frames of 1920x1080 pixels per second, or 62.2 million pixels per second. That's a small difference of 11%. After a bunch of hand waving and fancy encoding, both formats can, more or less, be transmitted at roughly the same data rate (somewhere less than 19 Mbps), which is extremely important for broadcast TV (but, yea, less so for cable and satellite).

Here are some serious complications with the new YouTube 1080p format:

Does 1080p even make any sense in a world where most viewers will not watch it full-screen 1080p anyhow?
Does 1080p make sense when most viewers do not even own a 1080p resolution monitor?
Since a 720p clip is more likely to be seen in HD than a 1080p clip, wouldn't it be better to have a selectable option? Or would this just confuse viewers?
Is 1080p better than other resolutions when embedded at 560x340 on a Webpage? What about when it's embedded on Facebook, et. al.?
What are the downsizing tricks YouTube is using for normal viewing? Do we automatically get 720p on our laptop? What about for iPods?

No matter the uncertainties, caveats and the fact that the vast majority of viewers will not be watching our lovingly crafted 1080p videos at anywhere near 1920x1080, I still believe that this is a game changer: YouTube supports 1080p and if you are shooting 1080p, then that is the format you should encode and upload from now on. Even if most viewers won't appreciate it (or even see it at full resolution) today, there's no reason not to upload the best quality you can.

References:
* For another example of 1080p resolution from YouTube, click this link and then click on the text toggle "watch in HD" located beneath the right hand corner of the player. {mos_fb_discuss:18}