[Xiaomi Redmi Note 7 Themes, Apps, and Mods] Quaresma_7:
So GCam is definitely the answer for getting the best photo quality out of this phone in almost any situation, but let's see how we can record the best possible video.

Btw, when you first try video recording with the Note 7 in low light, it's natural to be disappointed since you're comparing it to GCam's photo output in low light. GCam uses frame stacking and other techniques to remove noise, increase dynamic range and get details in both shadows and highlights as well as the rest of the image. To produce only one 12-megapixel frame, it uses anywhere from 3 to 15 frames and takes a few seconds to do the complex blending and computations to create a great low light photo. Without a much stronger SoC, ISP, a better sensor and more advanced processing algorithms, this is impossible to do while recording a video, as the phone is struggling to keep up with recording 30 8-megapixel frames (UHD) each second or 2-megapixel frames in case of 1080p. They've barely managed to get SD 660 to comfortably use real-time EIS at 1080p30, along with auto focusing, WB, exposure, noise reduction etc.

So, knowing that in low light this phone's video recording will never be great, let's focus on other aspects of its video recording. My only idea for improving low light video recording is to find an app that can use a high bitrate in order to avoid introducing additional noise and artifacts. This also applies to filming in daylight.

I'll start with some findings about the differences between the stock app, GCam and Open Camera when recording video.

STABILIZATION

As far as video stabilization goes, only stock camera's 1080p30 EIS properly uses gyro-EIS and that really is the most beautiful stabilization you'll get out of this phone. No wobbling or image distortion, it just softens the shakiness, as if the phone were on a gimbal.

1080p30 EIS in GCam – it's instantly noticeable that the viewfinder here is stabilized (whereas in the stock app it isn't). It appears to be using the gyroscope, but not in the same way the stock app does. Stabilization is OK, but not as smooth as in the stock app and wobbliness can be noticed occasionally, with more abrupt movement.

UHD EIS in GCam – better than no stabilization, but wobbliness on the edges tends to be obvious when there's a lot of movement.

1080p30 or UHD EIS in Open Camera – also a stabilized viewfinder, but the stabilization algorithm here is very wobbly, which is extremely noticeable in UHD, so try to hold the phone as stable as possible when recording in Open Camera. The highlight of Open Camera for the Note 7 is its front-facing camera UHD stabilized video recording. So far this is my only use case for Open Camera on this phone (plus testing).

If you like using 1080p60 because of its smoother panning and movement in general, here's a tip to stabilize 60 fps videos: shoot in 1080p60 without EIS in the stock app or another app (using a high bitrate when possible) and then stabilize the footage in Google Photos, which does a nice job unless the video is impossibly shaky.

SLOW MOTION

In my testing, I've never managed to get a smooth slo-mo video out of the stock app and I've tried it after every MIUI update so far. At 1080p or 720p, the result is always a stuttering slo-mo video. GCam to the rescue!

GCam can record stutter-free 1080p slo-mo for a long time (I tried it for a couple minutes) and the resulting video is smooth as butter, suffering only from an occasional hiccup here and there. Perfectly usable.

Open Camera can also record in 1080p120. Different apps should be tried out to see how smooth the slo-mo is and which one is able to use the highest bitrate, leading to the highest image quality. Although image quality does appear to be limited in slow motion mode.

FIELD OF VIEW (FOV)

If you have your phone on a tripod or you can lean on a surface to stabilize it, you should turn EIS off. This will give you a wider field of view and a sharper image. When you're recording a video, the top and bottom portions of the image are cut off to accommodate for the widescreen format. This already makes you lose around 25% of the image information that the sensor can actually see. EIS works by further zooming into the centre of the sensor (or cropping the image) and using the now-extra information to shift the frame in any direction as necessary, to produce an impression of a more stable footage.

The phone will not recognize that it's on a tripod and turn EIS off. You have to do that manually. Why would you want to do that? If you want:

1) to capture more of the scene (a wider field of view), with EIS on, you'll have to step back (which is sometimes not possible)

2) better image: stabilization comes with trade-offs. If you don't need it, turn it off. The phone will be able to use a greater number of pixels to create your fixed-resolution video, resulting in a better image.

With 1080p30 EIS off or UHD without EIS, you'll have the widest FOV possible for video on this sensor. Only top and bottom are cut off for widescreen.

1080p60 EIS off – for some reason, this has just slightly narrower FOV than 1080p30 without EIS. The same FOV appears to be present in 1080p120 (slow motion).

When EIS is on, it crops the least on the stock app, slightly more on GCam and the most on Open Camera.

VIDEO AND AUDIO BITRATES AND QUALITY

Work in progress. So far I can only tell that stock and BSG's GCam produce different videos. Stock uses a higher video bitrate and GCam a higher audio bitrate. Open Camera tends to put on a yellow cast, presumably to make the image warmer. Also, bulkin's GCam allows you to select video bitrate. Haven't played with that or the bitrate in Open Camera.

It's also worth to test other apps, such as Cinema FV-5. I've had luck with that on previous phones.