How Much Dynamic Range is in a Rec.709 File?

Ever since I started shooting video and consequently started trying to understand the myriad of standards and formats that come with it, I've always wondered about some of the simile fundamental points, like just how much dynamic range is there in a rec.709 format file?
Of course, you can google the answer, and you get something to the effect that a broadcast legal rec.709 file can contain 6 stops of dynamic range. Or 5.9 stops, or 5.5 stops, or some other number that falls somewhere between 5.5 and 6.5 stops depending on what source you look at.
Unfortunately, none of the sources that I could find, actually showed their work. So that's what I've done in this video. We'll look at the ITU BT-709 standard, and specifically the defined opto-electric transfer functions (the math that converts light levels into digital values) and the broadcast legal code points for black and white and see just how much dynmaic range there is.
On top of that, since many of our cameras these days ignore the broadcast legal range, and use the full range that can be stored, we'll also do the math for the full range case, and see just how much dynamic range can be stored there as well.
══════════════════════
💵 Support the Channel and Content Like This 💵
══════════════════════
⯈ Click the Thanks Button under the video.
⯈ Use PayPal: paypal.me/poin...
⯈ Buy yourself something from the affiliate links below.
⯈ Amazon.com: amzn.to/4dloDzU
══════════════════════
Gear I Use to Make Videos
══════════════════════
(Affiliate links)
⯈ Canon EOS R5 - amzn.to/3uJNNVI
⯈ Canon EOS R5 Mark II -
⯈ Canon EOS R5C - amzn.to/4goyveX
⯈ SmallRig NP-F Battery Adapter Pro (power for extended shooting time)- amzn.to/3ybCY3h
⯈ Anker Prime 27650 mAh Power Bank - amzn.to/4dsP8o4
⯈ Canon RF 15-35mm f/2.8L IS USM - amzn.to/37SuLDw
⯈ Canon RF 24-70mm f/2.8L IS USM - amzn.to/3M9I0yQ
⯈ Rode NTG2 -
⯈ Rode Wireless Go -
⯈ Zoom F6 - amzn.to/2TWsSvo
══════════════════════
Chapters
══════════════════════

[@rafograph]

Amazing info!

[@Couvrs]

❤

[@MartinMonkDotCom]

Could you give some conclusions from this? Aren't usual Web Deliveries finished in Video/Legal range i.e. 16-235 - so if for example you want to preserve highlights, you have maybe 2 stops below middle gray into blacks. That would give about the DR of Slide film for a typical h264 8Bit Delivery. Pretty shocking that this is still the standard.

[@jamestry]

I believe you may be ignoring the transfer function from video to display which scales output and enables theoretically infinite dynamic range albeit with only roughly 6 stops worth of gradation. once we surpass the '6 stops of dynamic range' of an 8 bit rec 709 video file we are essentially reducing the bitrate but increasing the dynamic range beyond the 6 stops. if we can capture 8 bit full range that bitrate (8 bit) stays constant up until roughly 10 stops of dynamic range at which point it starts to break down and banding is introduced.... with dither/film grain (as is seen in much cinema) the effective (perceptually smooth) dynamic range can be increased reasonably far beyond the theoretical limitations of an 8 bit files dynamic range.

[@PointsInFocus]

Changing the output transfer function doesn't change what's can be stored in the file, so it's not relevant. The only way to do that, change what's in the file, is to change the input transfer function, in which case it's not longer a rec.709 file and also no longer relevant to a discussion on the limits of a rec.709 file.

[@amrtoukhy1915]

This is shockingly interesting 🫡🙏