Versions and Characteristics of HDMI

HDMI 1.0
HDMI 1.0 was proposed in December 2002 and was the first standard released by HDMI. It introduced a multifunctional audio and video interface that could transmit video and audio signals through a single cable. With a data transmission speed of up to 4.95 Gbps, it supported a resolution of 1080p and 60 frames per second. Additionally, it supported 8-channel 192kHz/24-bit uncompressed audio (PCM). 

HDMI 1.1/1.2/1.2a
HDMI 1.1 was proposed in May 2004, based on HDMI 1.0, adding support for DVD-Audio. HDMI 1.2 was proposed in August 2005, achieving support for up to 8 channels of 1-bit audio (SACD audio streaming). It achieved a bandwidth of 4.95 Gbps, resolving the point-to-point issue of 1080p on the TV end. HDMI 1.2a version was proposed in December 2005, with the CEC channel function fully defined, and the compatibility verification certification became stricter; the Type C (mini HDMI) version was also launched. 

HDMI 1.3
HDMI 1.3 version was proposed on June 22, 2006, with the single link frequency increased to 340 MHz, i.e., the bandwidth increased to 10.2 Gbps. The bit depth increased from 24 bits to 30 bits, 36 bits, and 48 bits (RGB or YCbCr); it added support for Dolby True HD, automatic voice synchronization function, and DTS-HD MA high-definition audio streaming. 

HDMI 1.4
HDMI 1.4 was proposed on May 28, 2009, supporting resolutions of 24Hz/25Hz/30Hz @ 50 FPS/60 FPS @ 3840×2160, 1080p; it introduced the gigabit Ethernet channel (HDMI Ethernet Channel, HEC) function, allowing devices to share network connections via HDMI cables; in audio, HDMI 1.4 supported 8-channel LPCM 24bit/192kHz audio, as well as compressed audio formats (such as Dolby Digital, DTS) and 8-channel 1-bit DSD signals used by SACD, and also implemented the audio return channel (ARC) function, allowing the audio signal from the TV to be independently transmitted to the power amplifier receiver and audio equipment connected via HDMI cables for playback; the new Micro HDMI mini interface, compared to the standard A-type HDMI interface, has a size approximately half that of the standard HDMI interface.

HDMI 1.4a
HDMI 1.4a was proposed on March 4, 2010, adding support for 3D functions; it provided specifications and standards for 3D signal transmission between consumer electronic devices; in addition, the HDMI 1.4a standard specified the resolution and frequency standards for 3D display devices: 720p@50/60Hz (frame encapsulation format), 1080p@24Hz (frame encapsulation format), 1080i@50/60Hz (side-by-side or vertical format), etc.; mainly enhancing the CEC technology in terms of 3D functions, enabling better control of consumer electronic devices. 

HDMI 2.0/HDMI 2.0a
HDMI 2.0 was proposed in September 2013, with its bandwidth significantly expanded from 10.2 Gbps to 18 Gbps. It provided enhanced support for 4K ultra-high-definition video transmission and introduced improvements to multiple audio and video image technologies. It also enabled 4K@60 Hz video transmission in various color compression formats. It was backward compatible with HDMI devices. HDMI 2.0a was proposed on April 8, 2015, adding support for high dynamic range imaging (HDR), significantly enhancing image quality.

HDMI 2.1
HDMI 2.1 was proposed on January 4, 2017, with its bandwidth expanded from 18 Gbps to 48 Gbps. Thus, it could support 4K@120Hz and 8K@60Hz resolutions, achieving a maximum resolution of 10K. In terms of audio, it supported eARC functionality and improved support for high-quality audio transmission: it could transmit Dolby Atmos sound effects; it added support for high dynamic range imaging (dynamic HDR), which could enhance the light-dark representation of each frame to improve the light-dark performance of the scene; it enhanced video delay technology: it adopted fast frame transmission (QFT) and variable refresh rate (VRR) technologies to reduce or eliminate delays; it adopted optimized electromagnetic interference control to improve the stability and reliability of signal transmission.