AP - The Recognized Standard In Audio Test


Every device that bears a Dolby® logo is required to go through a compliance test process to insure that it meets Dolby technical requirements. Depending on the specific technology licensed, certifying the compliance of a device can involve hundreds of individual measurements. These measurements verify the correct behavior of a decoder including features such as bass management, dialog normalization, and bit exactness as well as signal-to-noise ratio, crosstalk, and other fundamental audio performance characteristics.

Audio Precision is an official Dolby Test Partner, working with Dolby to provide tools to support the implementation of their technologies and reduce compliance testing time from days to hours. AP instruments are referenced throughout Dolby certification manuals, and SDK-specific test software solutions developed by AP are available to Dolby licensees via the Dolby Customer Portal.

SDK Support and Compliance Testing

In tandem with Dolby engineers, Audio Precision has developed APx test solutions to support the Dolby MS11 Multistream Decoder SDK and the Dolby Digital Plus™ Consumer Decoder SDK. These APx test packages are available to all licensees via Dolby as described above. Depending upon the specific device under test (DUT), the compliance tests for each of these SDKs can include over a 1,000 individual measurements. If performed manually, such testing could easily take over a week. The APx solution reduces that time to hours. More importantly, because APx generates the test sequence with all appropriate limits, there is no time wasted on recreating a test methodology or deciphering test requirements.

Dolby test projects for Audio Precision analyzers are available exclusively from Dolby as part of the deliverables included in Dolby System Development Kits (SDK) for specific Dolby technologies. The projects are provided at no charge, but do require the appropriate AP audio analyzer to run.

Common Challenges

  • Certification is very time consuming and is prone to human error due to the large number of steps. For example, selecting the wrong transport stream will cause erroneous results.
  • Not all measurements have published limits. Dolby allows a range, but the acceptable values are confidential.

Tips for Efficient Testing

  • If there is a problem area, just run that test rather than going through the entire sequence each time.
  • Keep in close communication with Dolby throughout the verification process. They will provide detailed feedback based on your license application.
  • Check compliance early and often, so that any necessary changes can be incorporated into the design at the soonest possible stage. Sooner is cheaper.
  • Automate as much of the test as possible to ensure repeatability, reduce testing time, and lesse the risk of human error.

General Support: Testing Blu-ray & HD Audio Over HDMI

In addition to supporting compliance testing of specific Dolby SDKs, AP analyzers are ideally suited to testing consumer electronics, including those using Dolby technologies, in both R&D and production environments. APx analyzers are designed to output a wide array of encoded high-bitrate test streams over HDMI, which makes testing modern decoder devices such as surround sound receivers faster and more convenient. With the APx generator stimulating the receiver directly, no DVD is required, so entire sequences of tests can be run without the risk of human error (wrong track selection, etc.) or the introduction of compatibility issues with the source disc player.

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