color reproduction enhancing technology, in 2004, featured in the world's first LED-backlit LCD televisions. It was widely used in other Sony's products as well, including computer monitors, laptops, and smartphones. In 2013, Sony released a new line of televisions with an improved version of the technology, which incorporated quantum dots in the backlight system. It was the first commercial use of quantum dots. In 2012, the company revealed a prototype of an ultrafine RGB LED display, which it calls the Crystal LED Display. Audio recording Sony used the Compact Cassette format in many of its tape recorders and players, including the Walkman, the world's first portable music player. Sony introduced the MiniDisc format in 1992 as an alternative to Philips DCC or Digital Compact Cassette and as a successor to the Compact Cassette. Since the introduction of MiniDisc, Sony has attempted to promote its own audio compression technologies under the ATRAC brand, against the more widely used MP3. Until late 2004, Sony's Network Walkman line of digital portable music players did not support the MP3 standard natively. In 2004, Sony built upon the MiniDisc format by releasing Hi-MD. Hi-MD allows the playback and recording of audio on newly introduced 1 GB Hi-MD discs in addition to playback and recording on regular MiniDiscs. In addition to saving audio on the discs, Hi-MD allows the storage of computer files such as documents, videos and photos. Audio encoding In 1993, Sony challenged the industry standard Dolby Digital 5.1 surround sound format with a newer and more advanced proprietary motion picture digital audio format called SDDS (Sony Dynamic Digital Sound). This format employed eight channels (7.1) of audio opposed to just six used in Dolby Digital 5.1 at the time. Ultimately, SDDS has been vastly overshadowed by the preferred DTS (Digital Theatre System) and Dolby Digital standards in the motion picture industry. SDDS was solely developed for use in the theatre circuit; Sony never intended to develop a home theatre version of SDDS. Sony and Philips jointly developed the Sony-Philips digital interface format (S/PDIF) and the high-fidelity audio system SACD. The latter became entrenched in a format war with DVD-Audio. Still, neither gained a major foothold with the general public. CDs had been preferred by consumers because of the ubiquitous presence of CD drives in consumer devices until the early 2000s when the iPod and streaming services became available. In 2015, Sony introduced LDAC,