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Knowledge Base

The HDMI Licensing Knowledge Base is a library of current information about the HDMI standard. Select an appropriate category from the pull down below, or, you may use your own search terms to obtain results.

If your question involves a specific product, please contact the manufacturer directly. The HDMI Knowledge Base does not contain information about specific products.

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Q. What is the difference between Active HDMI and Passive HDMI?

There is no active or passive HDMI in the test specification. These terms apply to cables. Active cables have built-in electronics to enable long cable runs, and typically these cables require a power supply. These cables use active electronics to help push the signal farther than typical passive cables.

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Q. How do I obtain a license to the HDMI Specification?

HDMI is licensed under reasonable and non-discriminatory terms. The Adopter Agreement or Test Equipment Maker Agreement detailing the licensing terms is available in Becoming An Adopter in the Manufacturer area of this site. Please follow the instructions for downloading and submitting the appropriate agreement along with your payment in order to obtain a license to the Specification.

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Q. Can I review the HDMI Specification before deciding to pay for a license?

Yes. Before downloading the specification, you will need to fill out a short form. Please visit the Manufacturer area of this site to download the HDMI Specification.

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Q. When was the HDMI Specification released?

The initial HDMI 1.0 specification was released in December 2002.
Version 1.1 was released in May 2004.
Version 1.2 was released in August of 2005.
Version 1.2a was released in December of 2005.
Version 1.3 was released in June of 2006.

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Q. What functionality was added to each version of HDMI?

The following provides an overview of major functionality added to each version of HDMI:

HDMI 1.1:

  • Support for DVD Audio.

HDMI 1.2:

  • Adds features and capabilities that increase HDMI's appeal for use in both the CE and PC industries. Specifically, the features and modifications for HDMI 1.2 include: Support for One Bit Audio format, such as SuperAudio CD's DSD (Direct Stream Digital), changes to offer better support for current and future PCs with HDMI outputs, including: availability of the widely-used HDMI Type A connector for PC sources and displays with full support for PC video formats, ability for PC sources to use their native RGB color space while retaining the option to support the YCbCr CE color space, requirement for HDMI 1.2 and later displays to support future low-voltage (i.e., AC-coupled) sources, such as those based on PCI Express I/O technology.

HDMI 1.2a:

  • Consumer Electronic Control (CEC) features and command sets and CEC compliance tests are now fully specified.
  • Creation of version 1.2a of the HDMI Compliance Test Specification (CTS), which includes a CEC Supplement. HDMI CTS 1.2a has been updated for technical consistency with HDMI Specification 1.2a as well as to the recently released HDMI Specification 1.2.
  • Significantly, CTS 1.2a contains additional cable and connector testing and Authorized Testing Center (ATC) submission requirements. Specifically, under CTS 1.2a, the Adopter shall submit for testing to the ATC any new HDMI cable whose length exceeds previously tested cables.
  • Additionally, HDMI Licensing, LLC will maintain a list of approved connectors. For a device to pass CTS 1.2a testing at an ATC, all connectors on such device must appear on the approved connector list. To add a connector to this list, the vendor must submit to the ATC or HDMI Licensing, LLC full and passing testing results.

HDMI 1.3:

  • Higher speed: HDMI 1.3 increases its single-link bandwidth to 340 MHz (10.2 Gbps) to support the demands of future HD display devices, such as higher resolutions, Deep Color and high frame rates. In addition, built into the HDMI 1.3 specification is the technical foundation that will let future versions of HDMI reach significantly higher speeds.
  • Deep Color: HDMI 1.3 supports 10-bit, 12-bit and 16-bit (RGB or YCbCr) color depths, up from the 8-bit depths in previous versions of the HDMI specification, for stunning rendering of over one billion colors in unprecedented detail.
  • Broader color space: HDMI 1.3 adds support for “x.v.Color™” (which is the consumer name describing the IEC 61966-2-4 xvYCC color standard), which removes current color space limitations and enables the display of any color viewable by the human eye.
  • New mini connector: With small portable devices such as HD camcorders and still cameras demanding seamless connectivity to HDTVs, HDMI 1.3 offers a new, smaller form factor connector option.
  • Lip Sync: Because consumer electronics devices are using increasingly complex digital signal processing to enhance the clarity and detail of the content, synchronization of video and audio in user devices has become a greater challenge and could potentially require complex end-user adjustments. HDMI 1.3 incorporates automatic audio synching capabilities that allows devices to perform this synchronization automatically with total accuracy.
  • New HD lossless audio formats: In addition to HDMI’s current ability to support high-bandwidth uncompressed digital audio and all currently-available compressed formats (such as Dolby® Digital and DTS®), HDMI 1.3 adds additional support for new lossless compressed digital audio formats Dolby TrueHD and DTS-HD Master Audio™.
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Q. Are all of the new HDMI versions backward compatible with previous versions?

Yes, all HDMI versions are fully backward compatible with all previous versions.

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Q. How can I get the latest HDMI Specification?

Please visit the Manufacturer area of this site to download the HDMI Specification.

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Q. Do I need v1.3 HDMI to hear the new Dolby TrueHD and DTS Master HD audio content on HD-DVD or Blu-ray players?

No. The Dolby TrueHD, Dolby Digital Plus, and DTS-HD Master Audio can be decoded by the playback device into multi-channel Pulse Code Modulation (PCM) digital audio streams, which is an audio format standard that can be sent over any version of HDMI. In fact, all versions of HDMI can support up to 8 channels of PCM audio at 192kHz, 24 bits per sample.

To do this, consumers should ensure that their playback device (such as HD-DVD or Blu-ray player) is capable of decoding these new lossless Dolby & DTS audio formats into the PCM format on the HDMI output, and that the audio device (such as an A/V receiver) is capable of receiving multi-channel PCM audio over the HDMI inputs. Consult your user manual/product specification sheet to determine whether your device supports such PCM capabilities (we believe that nearly all HD-DVD and Blu-ray players will, but users should confirm this). Devices that support HDMI v1.3 and higher may also offer the option to transport the high definition audio formats as a compressed, encoded stream over HDMI so that the decoding function can be performed by the A/V receiver (whereas the above transport method has the playback device performing the decoding).

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Q. How can I get the Compliance Test Specification?

The latest version of the Compliance Test Specification is available to all parties that have licensed the HDMI Specification.

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Q. How can I view/get previous HDMI Specifications?

The easiest way to get any previous Specification is to download a current copy of the latest HDMI Specification. Each HDMI Specification revision has a "revision history" section located near the beginning of the document. This feature will categorize all of the changes and list the appropriate sections that were added/modified.

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Q. How can I tell the differences in each version of the HDMI specification?

Download a copy of the most recent specification of HDMI. At the beginning of the document, there is a section called "Revision History." In this section, you can view all of the the changes for each revision of the Specification.

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Q. What is the difference between DVI and HDMI?

HDMI is DVI with the addition of:

  • Audio (up to 8-channels uncompressed)
  • Smaller Connector
  • Support for YUV Color Space
  • CEC (Consumer Electronics Control)
  • CEA-861B InfoFrames

 

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Q. Why do I need HDCP?

HDCP is typically used in applications where copyrighted or protected content is delivered from one device to another. HDCP is an encryption method used in conjunction with DVI or HDMI. Using HDCP is transparent to the customer since all of the validation and encryption/decryption activities occur between devices.

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Q. What is TMDS and where can I learn about it?

TMDS stands for Transition Minimized Differential Signaling. This is the under-pinning protocol for both DVI and HDMI technologies. You can find out more about what TMDS is and how it works at www.siliconimage.com.

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Q. What is CEC?

CEC is Consumer Electronics Control. This is a single-conductor wire-or bus technology that is an optional feature in the HDMI v1.1 specification. The CEC is meant to carry IR/remote and/or control commands between HDMI devices that are interconnected. In theory, this allows for the “one remote” concept. CEC is not currently required for HDMI compliance. However, the ATC does test for proper CEC connectivity and electrical characteristics of the CEC net based on the capabilities of the device in question.

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Q. How does HDCP discourage pirating of protected content?

HDCP offers content protection for the link between devices; not generally for inside a device. HDCP performs encryption on the data just before the TMDS PHY in a source, and decrypts it just after the TMDS PHY in a sink. HDCP offers a system renewability feature that allows content providers to revoke keys from devices dynamically from the originating content source.

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