I am not going to say that specifically, as I haven't done enough tests.
However, there is a maximum data rate, and as the frame rate goes up the data rate limits how much data is allocated to each frame.
Considering data rate only
Just shooting a static test frame with no motion at 4K, 24 FPS gives a data rate of around 100mb/s, increasing the frame rate to 48 FPS data rate goes up, but only to about 115mb/s. Twice as many frames but only 15% more data. Now this is for shooting a test chart with no motion in the frame, motion frame will change the date rate significantly. The data rate on the
Mini 3 Pro is limited to 150mb/s.
If you are shooting at 60 FPS and your data rate is 150mb/s, that is 2.5mb per frame, and optimized for motion so you have key frames (I frames) and then frames that are made up of only the amount of change from the previous frame (P frames).
Taking a single JPEG is 3.8mb for that one frame, and optimized for a still image. A single raw image is 24mb.
IMPLICATION: the jpeg has 16% of the original data, and the h265 frame has only 10% of the original data.
Considering codecs
Modern image data compression is based on the perceptual qualities of the human vision system (HVS), and the HVS has these qualities:
- Contrast, edges, and fine detail are perceived from the luminance (lightness/darkness) of a scene, in V1, the first stage of the visual cortex.
- Color, meaning hue and chroma, and disregarding luminance, is processed separately by the visual cortex (and later, V4/V8) and importantly color is at a THIRD the resolution of luminance.
- Still imagery and motion are processed by separate parts of the brain.
- The visual cortex has a built-in sharpening filter.
- Neurologically, resolution gets added to the scene that is being viewed over time, as the eye's saccades scan over the scene, higher resolution visual information from the narrow central foveal area is added onto the lower resolution peripheral information, improving the perceived detail of the image the longer it is looked at.
JPEG, h264, and h265 are all using 4:2:0 chroma subsampling, meaning that the color information is at a quarter of the resolution of the luminance information, which is in accordance to the human vision system which relies on luminance for detail.
They are also all using some flavor of DCT compression, which uses mathematical transforms to throw away a certain amount of spatial data.
Moving Still
Even though a movie it's just a series of individual still frames, the way data is compressed for a single still versus a stream makes a very big difference.
Because JPEG is a single still frame, all of the compression happens within that one frame (intraframe or I frame) and it's optimized for viewing as a still image. The data that is thrown out through DCT and chroma subsampling is done in a way as to be minimally noticeable as a still image.
h264 and h265 are designed and optimized for streaming motion video, so a certain number of frames are I frames (i.e.. key frames), but the rest of the frames are P frames which only store the
change between the current frame and the previous frame. Because it is designed for streaming data is thrown out in a way that is minimally noticeable for
motion imagery.
h265 is a newer "more efficient" codec, designed to give better compression rates for an "equivalent" perceived quality for
motion video compared to h264. Nevertheless keep in mind that
"better compression rates" by definition means that more data is being thrown away.
TL;DR
Motion optimized codecs like h264/h265 throw away data a little differently than a still-optmized codec (such as JPEG), by taking advantage of how human vision adjusts/adds resolution over time.
As a result, don't expect a single frame grab from h265 to look as good as a JPEG still when the JPEG still has a much larger amount of data, and uses compression techniques intended for still images.
