Wireless HDMI key requirements
Wireless HDMI must provide cable-free HDMI repeater functionality:
- Transmission of the video data.
- Transmission of the audio data.
- Transmission of the EDID information.
- Transmission of the CEC data.
- Transmission of clock information.
The goal of wireless HDMI is to provide the same user experience as wired HDMI. From this, one can derive the key requirements in Table 2
Table 2: Key requirements for wireless HDMI
Although operation within a single room is a minimum requirement, it is very desirable for a wireless HDMI solution to extend this throughout the entire home, stretching the value proposition to consumers to the maximum.
Low cost does not necessarily mean same price point as an HDMI cable. The convenience factor gained from cutting the cord is well worth paying for in the minds of consumers. However, the magical retail price ceiling is somewhere around the $200 per Tx/Rx pair at the onset of the market and dropping to sub $80 as the market matures.
Wireless HDMI challenges
The bit rates for different HD and SD video formats transmitted over an HDMI cable are listed in Table 3.
Table 3: Bit rates for HD and SD formats
At these bit rates even the fastest of the broadband wireless radios in Table 1 is challenged to beam raw 1080p60 at the minimum of 24 bits/pixel. Note from Table 4 that although compressed multi-channel HD audio can consume significant amounts of bandwidth, it still is relatively insignificant compared to raw HD or SD video streams.
1) HRA = High Resolution Audio
2) MA = Master Audio
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Table 4: Compressed audio bit rates
Another challenge that faces wireless transmission links is the substantial fluctuations in bandwidth that can occur due to interference by other radios in the same frequency band and by obstacles in the transmission path, notwithstanding the significant advancements in array signal processing and beam forming.
Next: To compress or not to compress, the H.264 video compression standard, and Super Low Latency technolgy