4K resolution
The term "2160p" could be applied to any format with a height of 2160 pixels, but it is most commonly used in reference to the 4K UHDTV resolution of 38402160 due to its association with the well-known 720p and 1080p HDTV formats. Although 38402160 is both a 4K resolution and a 2160p resolution, these terms cannot always be used interchangeably since not all 4K resolutions are 2160 pixels tall, and not all 2160p resolutions are ≈4000 pixels wide. However, some companies have begun using the term "4K" to describe devices with support for a 2160p resolution, even if it is not close to 4000 pixels wide. For example, many "4K" dash cams only support a resolution of 28802160 (4∶3); although this is a 2160p resolution, it is not a 4K resolution. Samsung also released a 51202160 (64∶27) TV, but marketed it as a "4K" TV despite its 5K-class resolution.
Home cinema
By the mid-2010s, the Blu-ray Disc medium had become a common home media standard, and online video streaming sources such as Netflix and YouTube were offering a range of high definition content, including some 4K content (although various compression technologies are applied to make this streamed content feasible). The first 4K Blu-ray discs were released in 2016. By this point, 4K TVs and computer monitors were rapidly declining in price and increasing in prevalence, despite a lack of native 4K content. While many DSP systems existed, DTS-HD Master Audio remained the studio standard for lossless surround sound encoding on Blu-ray, with five or seven native discrete channels. High definition video projectors also continued to improve and decrease in price, relative to performance.