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[电脑] HDMI 2.1与2.0线材的疑问

引用:
A diagram of a type A HDMI receptacle, showing 10 pins on the top row and 9 pins on the bottom row (total 19 pins).

HDMI type A receptacle
Pin 1        TMDS Data2+
Pin 2        TMDS Data2 Shield
Pin 3        TMDS Data2−
Pin 4        TMDS Data1+
Pin 5        TMDS Data1 Shield
Pin 6        TMDS Data1−
Pin 7        TMDS Data0+
Pin 8        TMDS Data0 Shield
Pin 9        TMDS Data0−
Pin 10        TMDS Clock+
Pin 11        TMDS Clock Shield
Pin 12        TMDS Clock−
Pin 13        CEC
Pin 14        Reserved (HDMI 1.0–1.3a) Utility/HEAC+ (HDMI 1.4+, optional, HDMI Ethernet Channel and Audio Return Channel)
Pin 15        SCL (I2C serial clock for DDC)
Pin 16        SDA (I2C serial data for DDC)
Pin 17        Ground (for DDC, CEC, ARC, and HEC)
Pin 18        +5 V (min. 0.055 A)[3]
Pin 19        Hot Plug Detect (all versions) HEAC− (HDMI 1.4+, optional, HDMI Ethernet Channel and Audio Return Channel)
从接口外观上,长得一样,Pin 1 ~ Pin 19的物理规范,HDMI2.1也没比2.0特殊在哪。
是不是用料比较好的HDMI 2.0线材也可以当作HDMI 2.1线材使用?支持HDMI 2.1规范的新特性?
引用:
Version 2.0
HDMI 2.0, referred to by some manufacturers as HDMI UHD, was released on September 4, 2013.[112]

HDMI 2.0 increases the maximum bandwidth to 18.0 Gbit/s.[112][113][114] HDMI 2.0 uses TMDS encoding for video transmission like previous versions, giving it a maximum video bandwidth of 14.4 Gbit/s. This enables HDMI 2.0 to carry 4K video at 60 Hz with 24 bit/px color depth.[112][115][116] Other features of HDMI 2.0 include support for the Rec. 2020 color space, up to 32 audio channels, up to 1536 kHz audio sample frequency, dual video streams to multiple users on the same screen, up to four audio streams, 4:2:0 chroma subsampling, 25 fps 3D formats, support for the 21:9 aspect ratio, dynamic synchronization of video and audio streams, the HE-AAC and DRA audio standards, improved 3D capability, and additional CEC functions.[112][117]

HDMI 2.0a was released on April 8, 2015, and added support for High Dynamic Range (HDR) video with static metadata.[118]

HDMI 2.0b was released March, 2016.[119] HDMI 2.0b initially supported the same HDR10 standard as HDMI 2.0a as specified in the CTA-861.3 specification.[117] In December 2016 additional support for HDR Video transport was added to HDMI 2.0b in the recently released CTA-861-G specification, which extends the static metadata signaling to include Hybrid Log-Gamma (HLG).[117][120][121]
引用:
Version 2.1
HDMI 2.1 was officially announced by the HDMI Forum on January 4, 2017,[81][82] and was released on November 28, 2017.[122] It adds support for higher resolutions and higher refresh rates, including 4K 120 Hz and 8K 120 Hz. HDMI 2.1 also introduces a new HDMI cable category called Ultra High Speed (referred to as 48G during development), which certifies cables at the new higher speeds that these formats require. Ultra High Speed HDMI cables are backwards compatible with older HDMI devices, and older cables are compatible with new HDMI 2.1 devices, though the full 48 Gbit/s bandwidth is not possible without the new cables.

Additional features of HDMI 2.1:[123][122]

Maximum supported format is 10K at 120 Hz
Dynamic HDR for specifying HDR metadata on a scene-by-scene or even a frame-by-frame basis
Display Stream Compression (DSC) 1.2 is used for video formats higher than 8K with 4:2:0 chroma subsampling
High Frame Rate (HFR) for 4K, 8K, and 10K, which adds support for refresh rates up to 120 Hz
Enhanced Audio Return Channel (eARC) for object-based audio formats such as Dolby Atmos and DTS:X
Enhanced refresh rate and latency reduction features:
Variable Refresh Rate (VRR) reduces or eliminates lag, stutter and frame tearing for more fluid motion in games
Quick Media Switching (QMS) for movies and video eliminates the delay that can result in blank screens before content begins to be displayed
Quick Frame Transport (QFT) reduces latency by bursting individual pictures across the HDMI link as fast as possible when the link's hardware supports more bandwidth than the minimum amount needed for the resolution and frame rate of the content. With QFT, individual pictures arrive earlier and some hardware blocks can be fully powered off for longer periods of time between pictures to reduce heat generation and extend battery life.
Auto Low Latency Mode (ALLM) – When a display device supports the option to either optimize its pixel processing for best latency or best pixel processing, ALLM allows the current HDMI source device to automatically select, based on its better understanding of the nature of its own content, which mode the user would most likely prefer.
Video formats that require more bandwidth than 18.0 Gbit/s (4K 60 Hz 8 bpc RGB), such as 4K 60 Hz 10 bpc (HDR), 4K 120 Hz, and 8K 60 Hz, may require the new "Ultra High Speed" or "Ultra High Speed with Ethernet" cables.[82] HDMI 2.1's other new features are supported with existing HDMI cables.

The increase in maximum bandwidth is achieved by increasing both the bitrate of the data channels and the number of channels. Previous HDMI versions use three data channels (each operating at up to 6.0 GHz in HDMI 2.0, or up to 3.4 GHz in HDMI 1.4), with an additional channel for the TMDS clock signal, which runs at a fraction of the data channel speed (one tenth the speed, or up to 340 MHz, for signaling rates up to 3.4 GHz; one fortieth the speed, or up to 150 MHz, for signaling rates between 3.4 and 6.0 GHz). HDMI 2.1 doubles the signaling rate of the data channels to 12 GHz (12 Gbit/s). The structure of the data has been changed to use a new packet-based format with an embedded clock signal, which allows what was formerly the TMDS clock channel to be used as a fourth data channel instead, increasing the signaling rate across that channel to 12 GHz as well. These changes increase the aggregate bandwidth from 18.0 Gbit/s (3 × 6.0 Gbit/s) to 48.0 Gbit/s (4 × 12.0 Gbit/s), a 2.66x improvement in bandwidth. In addition, the data is transmitted more efficiently by using a 16b/18b encoding scheme, which uses a larger percentage of the bandwidth for data rather than DC balancing compared to the TMDS scheme used by previous versions (88.8% compared to 80%). This, in combination with the 2.66x bandwidth, raises the maximum data rate of HDMI 2.1 from 14.4 Gbit/s to 42.66 Gbit/s, approximately 2.96x the data rate of HDMI 2.0.[124][125]

The 48 Gbit/s bandwidth provided by HDMI 2.1 is enough for 8K resolution at approximately 50 Hz, with 8 bpc RGB or Y′CBCR 4:4:4 color. To achieve even higher formats, HDMI 2.1 can use Display Stream Compression with a compression ratio of up to 3:1. Using DSC, formats up to 8K (7680 × 4320) 120 Hz or 10K (10240 × 4320) 100 Hz at 8 bpc RGB/4:4:4 are possible. Using Y′CBCR with 4:2:2 or 4:2:0 chroma subsampling in combination with DSC can allow for even higher formats.[123]

HDMI 2.1 includes HDR10+ as part of Vendor Specific Data Block with OUI 90-84-8b for "HDR10+ Technologies, LLC".[126][127]


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前阵子,我买了根5米长的HDMI 2.1的线材,斯泰克,便宜量又足,
结果实际连4K60 10bit RGB都做不到,颜色范围必须降级到YCbCr444,强拉RGB和60帧的后果就是黑屏,不识别设备。
赶紧退货换了根3米的开博尔,4K120 10bit RGB都没问题了。

结合楼上几位的观点,总结一下,也不是第一根线材质量有问题,完全是5米的距离,按铜缆的导电率,数字信号已经衰减降级了。
这也是为什么市面上,超过3米的HDMI 2.1线材绝大多数都是光纤&铜缆的混合线了。



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引用:
JCE此次取得的HDMI2.1 UHS Cable长度为5m,线规为26AWG(对绞), 使用自行设计开发的HDMI2.1连接器搭配Shielding Case的结构, 採用全自动化的专利制程加工工艺,完全考量及确保了使用的可靠性与信号完整性.
https://conn.big-bit.com/news/360143.html


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