Mini 2 Video Artifacting

k4rl0s · Jul 4, 2021

Hi Guys, I have done some searching and believe this is a common issue but thought would link a comparison to see if this is what everyone else expects.

For photos and almost no motion shots absolutely fine, but shooting anything with movement that has detail, the video quality shows a lot of artifacting.

Here are two shots one from an Ipad the other Mini 2, both using the same settings as near as possible. As these are both small sensor devices I can only assume its the processing power of the Mini 2 that is letting it down.

These are a couple of frame stills, you can see the artifacts on the slate tiles, yet nothing from the ipad.

Ipad-Pause hosted at ImgBB

Image Ipad-Pause hosted in ImgBB

ibb.co

Mini-2-Pause hosted at ImgBB

Image Mini-2-Pause hosted in ImgBB

ibb.co

Originals if the files get compressed;

YGXR1065-002.mkv

drive.google.com

Mini 2 Pause.png

drive.google.com

Ipad Pause.png

drive.google.com

DJI_0005-009.mkv

drive.google.com

66427cobra · Jul 6, 2021

I'm not exactly sure what area of the video your are referencing. I see some artifacts in the slate and also in the pebbles. If those are the areas, they are MPEG artifacts. They are a result of the compression (video encoding) that is implemented to allow the video to fit within the available bandwidth.

Uncompressed HD video is ~1.5 Gbps. Uncompressed 4K is ~6 Gbps. There are many video compression formats; MPEG-2, MPEG-4, and AVC are some of the most common. There are other less common formats and future formats that will be developed. All are used to allow these very high bit rate videos to fit onto your microSD card (or for transmission over the internet, satellite, or microwave).

Take the slate area of the video. Since the color is the same in large areas, the compression algorithm sends one segment of the slate color and then, instead of sending that info again, it essentially says "repeat for these other areas". This happens in the same frame (spatially), and in consecutive frames (temporally). The pebble area is quite difficult to compress because of the movement and highly variable nature of the image.

The video is composed of I-Frames, B-Frames, and P-Frames. I-Frames contain all the video info, B-Frames will have only info that changed from the previous frame, and P-Frames are predicted frames which do motion estimation. A GOP (Group of Pictures) is typically comprised of an I-Frame, P-Frame and many B-Frames. A GOP of 15 would mean an I-Frame is sent every 15 frames of video.

If you have a particularly challenging subject to video, you may see fewer artifacts in HD than in 4K. This is because the encoder is working on 1.5 Gbps instead of 6 Gbps.

The above is a VERY general summary of video compression. Hopefully, it makes sense as to why some videos contain artifacts. You will see similar artifacts on your TV. Maybe more so if you stream your video over a low speed internet connection.

Good luck...

k4rl0s · Jul 6, 2021

Long story short, same compression etc on both devices, why does the mini 2 show it on the slate but not the iPad ?

66427cobra · Jul 6, 2021

k4rl0s said:
Long story short, same compression etc on both devices, why does the mini 2 show it on the slate but not the iPad ?

when you say on the mini 2, what do you mean? are you viewing the video from the SD card on your computer? And on the iPad, is that viewing live or from the album feature on the app?

What format is the video as capture on the SD card? 4K?

66427cobra · Jul 6, 2021

k4rl0s said:
Long story short, same compression etc on both devices, why does the mini 2 show it on the slate but not the iPad ?

maybe i am misunderstanding. is one recording done on the mini 2 and one using video recording on the iPad?

If that is the case then it is likely the mini 2 encoder is not as good as the one in the iPad. All H.264 is not created equal. you may find that one performs better than the other under different circumstances.