The ASUS ZenFone 2 Review

Video Performance

The other side of a phone's camera quality is how it performs when taking video. I've actually noticed an increased number of people taking videos now that the warm weather of summer has returned to Canada. Taking videos is also arguably a more intensive test of camera quality than taking still photos. A device's image signal processor needs to do post-processing in a much shorter time interval, and on devices where OIS is supported there's no way to use it to enable long exposure times as the frame rate of the video needs to be fixed high enough to keep the illusion of motion intact.

The ZenFone 2 has 3 different video settings, although the first one is 480p and not really worth discussing. The other two are the 720p30 and 1080p30 modes. While one may be tempted to just use the highest resolution mode, the caveat with 1080p30 recording is that there's no form of electronic video stabilization. ASUS also has a setting for choosing between quality and performance when recording. I assume that the performance setting is reducing frame drops at the expense of bitrate, but I didn't notice any difference in smoothness between the two modes so I recorded all the test footage using the quality setting.

The first video test is a video taken from a relatively stationary position. This gives an idea of what video quality is like without the effects of hand shake and so the device's ISP is really what will determine whether a device does well or not. I've taking recordings in both the 720p30 mode with digital stablization, and the 1080p30 mode without the EIS.

In this test the 1080p mode is the clear winner. The impact of EIS when recording at 720p is minimal, and the 720p footage is so blurry that it almost looks like upscaled 480p footage. The ZenFone 2 encodes 720p footage at 8Mbps using the H.264 Baseline profile. 1080p footage is encoded at 15Mbps and also uses H.264 Baseline. Unfortunately, even the 1080p footage isn't very impressive. There's just a general lack of sharpness throughout the entire frame.

The next test makes things more interesting by adding a significant amount of camera movement. This is where the use of EIS in the 720p mode will come into play, while the 1080p mode will most certainly have a higher degree of shakiness.

In this test it's clear that the 720p is much more stable than the 1080p footage overall. However, there are numerous instances where the the camera moves too far from its original position and the video drops frames as it settles on a new position. There's also a significant amount of high frequency shaking which makes the entire video look like it's wobbling back and forth very quickly. Both of these issues are very similar to what you see with video that is stablized using OIS, which is strange because the ZenFone 2's camera doesn't have OIS.

Unfortunately, the 720p video is again very blurry. The 1080p video is better, but is also not near as good as the output from other smartphones. It doesn't appear that there's any degree of EIS being used to stabilize the 1080p footage either. Both modes suffer from some noticeable processing issues, including halos where branches of trees are in front of the sky.

At this point it's becoming fairly evident to me that the ISP is being used in the ZenFone 2 is very far behind the competition. It would be nice if ISPs in mobile were less opaque so we had a better idea of what goes on at that stage in the pipeline. Whatever the cause may be, the ZenFone 2's video output is fairly uninspiring. If you do need to take a video with it I would still use the 1080p mode despite the shakiness, as the 720p mode is just far too blurry.