Audio Precision Introduces “Logic Analyzer” View for Digital Audio

Created on 2009-05-08 17:49:00

Metadata features in latest APx update make HDMI implementation & troubleshooting easier 

126th AES Convention, Munich, May 8th, 2009: Audio Precision, the recognized standard in audio test and measurement, has announced a number of new features for their APx Series audio analyzers relating to the display, analysis and control of metadata in HDMI and IEC60598/AES3 digital audio streams. 

The additional features are available in the first beta release of APx500 v2.4 which Audio Precision staff are demonstrating on their stand (1503) at the AES show, Munich, from May 8-10, 2009. The full version of APx v2.4 is due to be released later this year.

“Errors in metadata can cause real problems in HDMI that we just don’t see in S/PDIF,” explains Dan Knighten, Director of Products at Audio Precision. “A logic analyzer view shows exactly what’s going on over time so you can identify what’s causing glitches or other issues. There’s no better way to troubleshoot these kinds of problems.”

The new APx software release has three new features relating to metadata analysis and management:

• Two new Metadata Monitors. The first of these allows the decoding and display of the entire  HDMI audio InfoFrame, including current N and CTS values, HDCP state, audio layout and A/V mute condition, while the second displays the channel status and user bits information embedded in IEC60958/AES3-format audio (SPDIF, Toslink, AES/EBU). Both the HDMI and IEC60598 audio monitors also display digital audio stream type and sample rate, along with Dolby and DTS  parameters including ACMOD/AMODE value, dialog normalization level and bit rate.

• Two new Metadata Editor Panels, which allow users and test engineers to override default metadata settings, and set channel status information and HDMI Audio InfoFrame data to any value. These panels can be used to verify the response of a device under test to both valid and invalid settings.

• The Metadata Recorder, an easy-to-read colored display capable of plotting the changing states of multiple metadata fields in real time, like a logic analyzer. Up to 15 fields can be displayed simultaneously, allowing engineers to monitor in detail what happens to metadata information when an HDMI device is hot-plugged, or exactly when and where data glitches occur in a corrupted audio stream. Discrepancies between the indicated metadata and that being received are also automatically identified and flagged (for example, if the input sample rate is 48kHz but the channel status indicates that it should be 44.1kHz). The results of such measurements are invaluable in verifying that a device under test is behaving in compliance with relevant specifications.

A beta release of APx2.4 with these features is available to download from the Audio Precision web site at

Logic analyzer


About Audio Precision

Audio Precision is the recognized standard in audio test and measurement. Since 1984, AP has offered high performance audio analyzer instruments and applications to help engineers worldwide design and manufacture all types of consumer, professional and industrial audio products. For more information, visit