HDMI is the abbreviation for High Definition Multimedia Interface, which means High Definition Multimedia Interface. It is a digital video/audio interface technology. It is a special digital interface suitable for image transmission. It can transmit audio and video signals simultaneously. The maximum data transmission speed is 48Gbps (version 2.1).
At the same time, data / mode or analog to digital conversion is not necessary before signal transmission. HDMI can be combined with Broadband Digital Content Protection (HDCP) to prevent unauthorized copying of copyrighted audio and video content.
The extra space that HDMI has can be applied to the upgraded audio and video formats in the future.
Because a 1080p video and an 8-channel audio signal require less than 0.5GB/s, HDMI still has a lot of margin. This allows it to connect DVD players, receivers and PRR with one cable.
HDMI identification mode
HDMI Licensing, LLC released HDMI Specification Version 1.4A on behalf of HDMI original developers on March 4, 2010, featuring key enhancements for 3D applications, the addition of a mandatory 3D format for broadcast content, and a 3D format called Top-and-Bottom.
Because the term "HDMI 1.4" is too broad to show the specific support technology for the device, it is completely prohibited in this specification to use a version number identification method such as "HDMI 1.4". According to the new version of "Trademark and Logo Usage Specification", HDMI cable manufacturers prohibit the use of version number labels when selling and publicizing HDMI version 1.4 standard cables. Old versions of cables should remove all labels, instructions, packaging labels with version numbers within one year.
Except for cable HDMI, all version numbers should be removed by January 1, 2012. Prior to this, vendors should apply a version number label, such as "HDMI v.1.4 with Audio Return Channel and HDMI Ethernet Channel" (HDMI version 1.4 supports ARC audio feedback channel and HEC Ethernet channel), without explicitly displaying the technology used, but the use of a general "HDMI v.1.4 compliant" (compatible with HDMI 1.4) is strictly prohibited. ).
There are 5 types of cables in the HDMI version 1.4.
Standard HDMI Cable Chinese Specification Name: Standard HDMI line supports up to 2160p (3840x2160, or 4K) / 30HZ
Standard HDMI Cable with Ethernet standard Ethernet HDMI line
Standard Automotive HDMI Cable standard car HDMI line
High Speed HDMI Cable high speed HDMI line supports 1080p, DeepColor, 3D
High Speed HDMI Cable with Ethernet high speed Ethernet HDMI line
HDMI can not only meet the resolution of 1080P, but also support DVD Audio and other digital audio formats, support octave 96kHz or stereo 192kHz digital audio transmission, can transmit uncompressed audio and video signals. HDMI can be used in set-top boxes, DVD players, personal computers, TV amusement, amplifiers, digital audio and television sets. HDMI can transmit audio and video signals at the same time.
HDMI supports EDID and DDC2B, so the device with HDMI has the feature of "plug and play". There is automatic "negotiation" between signal source and display device to select the most suitable video/audio format.
Compared with DVI, the size of HDMI interface is smaller, and the optimal distance of HDMI/DVI cable length is not more than 8 meters. As long as one HDMI cable can replace up to 13 analog transmission lines, can effectively solve the home entertainment system behind the wire tangled problem.
Output compatibility test
1. compatibility with HDMI interface TV: simultaneous transmission of audio and video;
Compatibility of 2. and DVI interface TV: transmit video only;
3. and HDMI interface power amplifier compatibility: only transmit audio;
Judgment criteria: HDMI interface can transmit audio support "any compressed digital audio output through S/PDIF" and "2/6/8 channel, 32-192KHZ sampling rate of uncompressed digital audio", can output "I2S (a digital transmission interface, time difference performance is better than S/PDIF, suitable for short-range communication) and S PDIF audio" HDMI interface can transmit video with "HD1080I", "HD720P", "ordinary interlace" and "ordinary line-by-line". It also supports NTSC and PAL TV formats. It can automatically output "YUV" or "RGB" encoded video formats according to the acceptable video status of the receiving end.
Port plug and pull reliability test
1. Interface Hot Plug Reliability: In the condition that both the disk and the receiver are working, plug-in HDMI interface, whether the devices at both ends are working properly, whether the audio and video output function of HDMI is normal;
3. Interface plug-and-pull life test: plug-and-pull HDMI interface several times to test the life of HDMI interface; Judgment criteria: Hot plug-and-pull receiving terminal can normally output HDMI audio and video signals, the source system should still work normally; Interface plug-and-pull life at least 5000 times;
Reliability test of output
1. source output drive capability test;
2. the attenuation characteristic test of the connecting line.
3. high frequency and large capacity data transmission reliability;
Judgment criteria: up to 30 meters can be transmitted to ensure the normal sound image; large capacity DVD (multi-caption, multi-channel) disc playback screen fluency;
4. boot, standby, HDMI output is normal.
Please refer to HDMI interface and connection line supplier's testing standards.
HDMI port output test under abnormal working condition
1. high and low temperature:
2. high and low pressure:
3. long working hours:
Judgment criteria: Specific parameters of temperature, voltage and working time refer to the ordinary disk drive; in these states, the audio and video functions that require HDMI interface work normally;