Atlona Help Center

KB01516 - OmniStream Video Interface & Codec

SKU: AT-OMNI-1xx/5xx


Q: What codec does OmniStream use?

A: Answer – VC-2, also known as Dirac Pro.


Q: What is the recommended bitrate for the encoder?


  1. OmniStream Pro – UHDp30, 800 Mbps. For 1080p60, 400 Mbps.
  2. OmniStream R-Type bit rate is fixed at 800 Mbps, regardless of resolution.


Q: What is the difference between VC-2 Video mode and VC-2 PC mode?

A: VC-2 compression supports several encoding profiles. Some profiles yield better video quality when it comes to motion video (hence Video mode), while other profiles provide better video quality when it comes to computer-generated content (hence PC mode).


Q: Which VC-2 modes are available on OmniStream?

A: OmniStream Pro can support both Video mode and PC mode (user-configurable). OmniStream R-Type supports Video mode only.


Q: Does OmniStream support 4:4:4, 4:4:2 or 4:2:0?

A: OmniStream Pro system supports both 4:4:4 and 4:2:2 video processing; OmniStream R-Type supports 4:2:0 video processing only. Note that R-Type can accept 4:4:4 or 4:2:2 video; the R-Type encoder will downsample the video to 4:2:0.


Q: Should we accept lower video quality when processing 4:2:0 versus 4:2:2 or 4:4:4?


  • For motion video coming from Blu-ray players, streaming media players, and set-top boxes, 4:2:0 processing is sufficient – there will be no video quality degradation since the original content is sent with 4:2:0 chroma subsampling.
  • For PC-generated content (spreadsheets, slide deck presentations, etc.), higher chroma sampling comes into play. Based on our subjective video quality analysis, there is very little difference between images that are processed as 4:4:4 and 4:2:2, and slightly greater difference between computer-generated content processed with 4:2:0 vs. 4:4:4 or 4:2:2. We strongly recommend using 4:2:2 for OmniStream Pro versions as it provide the optimal balance between video quality and required bit rate to transmit the video.


Q: Can you send more than one video signal on a single Ethernet cable?

A: Yes, for OmniStream Pro systems, but the total bitrate for all streams must be below 1 Gbps. This typically means the resolution must be 1080p60 or less.

No, for OmniStream R-Type, since each video service is encoded and streamed at fixed bit rate of 800 Mbps. Video from HDMI input #1 is always mapped to Ethernet port 1, HDMI input #2 is always mapped to Ethernet port 2.


Q: How do you send more than one UHD signal on a single Ethernet cable?

A: This is not recommended. You would have to reduce the bitrate enough to make all the signals within 1 Gbps, which would have a substantial impact on video quality.


Q: How is EDID managed with OmniStream?

A: In short, in a similar manner to our HDMI / HDBaseT matrix switchers. See section 4.5.6 of the OmniStream spec document for a detailed description.


Q: What HDCP version is supported by OmniStream?

A: HDCP 2.2 is supported by AT-OMNI-111/112/121, as well as AT-OMNI-521/512. The AT-ONMI-122 dual-channel decoder does not support HDCP 2.2.



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