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HDMI audio transmission function analysis

Before HDMI was released, there were two main ways to transmit digital audio signals, one was digital coaxial cable using standard RCA interface and the other was SPDIF optical fiber transmission. These two earlier transmission technologies, each with its own advantages in signal transmission quality and characteristics, are able to achieve the goal of digital audio signal transmission relatively well. In HDMI HD cable in the audio and video signal transmission quality, farther these two modes of transmission.

HDMI technology, on the other hand, combines the advantages of both: in the physical layer it does not use fiber optic connections with strict requirements for synchronization timing, but instead uses a mature cable connection. Secondly, HDMI can theoretically achieve up to 20 meters of loss-free digital audio signal propagation, which is also better accepted for users who have requirements for distance. Finally, the combination of video cable and audio cable effectively reduces the user's purchase cost, but also allows the device side to achieve a slimmer, while reducing the manufacturer's production costs.

Coaxial cable interface standard for the device side of the hardware requirements are lower, but in the transmission of high-frequency signal, easy to occur relatively large attenuation, affecting the final sound quality.

Compared to coaxial transmission, optical fiber on the equipment receiving, transmitting end of the synchronization requirements are very strict, technically more difficult to achieve than coaxial, and whether using optical fiber transmission, or coaxial cable transmission, you need to buy a separate cable, for users, it means that the use of cost and complexity of the increase. The use of optical fiber can reduce costs while simplifying the wiring structure.

HDMI audio format support format is very broad, mainly located in the home theater applications, the PC field with HDMI output audio signal also requires more graphics and sound card manufacturers, so the most mainstream digital audio format in the AV field is also the general trend of HDMI. At the same time, with the popularity of digital electronic devices, digital companion functions are also widely used on HDMI.

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