This multifunction video test unit can test audio and video HDMI sources and sinks. As well as testing the audio and video streams, other aspects of the video link are also capable of being tested such as the EDID, HDCP state and CEC. As well as the HDMI input and output, an analogue component (VGA) output is also provided. Control of the unit is either by a large clear touchscreen display or (for automated test environments) by use of text commands sent over a serial link from a host PC.
Designed for portability, the 780B HDMI video tester is the ideal video test tool to take to an installation to troubleshoot HDMI audio and video problems. The video tester is battery powered, so may be easily carried from video link to video link without the hassle of having to try and find a spare power point or carry an extension lead around. Scripted video tests for HDMI source and sink devices means that the installer cannot accidentally overlook a particular test that might be required when commisioning a video system to ensure problem free operation. The large (7") LCD touchscreen is used to both setup and control the 780B video tester, but also to view the test results. There are modes of operation where the 780B HDMI video tester can even work as a small battery powered HDMI television, capable of showing the received video with diagnostic information, and sound from either from an internal speaker or via a 3.5mm socket for external headphones (not supplied).
The 780B ultra HDMI video tester may be used in a number of ways
- HDMI/DVI Source testing
- HDMI/DVI Sink testing
- HDMI/DVI Cable testing (requires 95-00056 option)
- HDMI/DVI Link testing (requires 95-00063 or 95-00064 options)
HDMI / DVI Source testing
There are a number of ways that to Quantum Data 780 may be used to test a source. It is possible to inspect the video image itself, timing, HDCP status, Info frames and embedded audio. Inspection and analysis of 3D video is supported.
It can act as a display, with the video input (any resolution to 4K) scaled down to fit onto the integrated 800x480 LCD display. It can act as a display with the image scaled down still further so that there is a status area visible to display timing, colour space, colour depth, HDCP status and other useful information about the received HDMI video. It can also capture a frame from the input at full received resolution, with the user able to pan the 800x480 window around the captured HDMI image with the touchscreen.
There is packet viewer tool that reports the received info-frames and shows both raw and decoded info-frame packet data. These reports may be saved as a text file to the Quantum Data 780 HDMI video tester for later inspection and analysis if required.
The format analyser measures the received HDMI timing from the source. This is real measured data as opposed to the timing reported in the info-frames which of course be different if there was a problem with the video. Reported data includes total pixels as well as active pixels; HSYNC and VSYNC position, width and polarity; AVMute and HDCP status; Colour depth, etc. The Quantum Data 780 will try and match received timing to the closest recognised video format and will highlight any discrepancies between what is received and what is expected.
For HDMI inputs, the built in Audio Analyser will display the audio format, sample rate, word length, channel allocation etc reported by the audio info-frames. However, for debug purposes the N and CTS ACR (Audio Clock Regeneration) registers are also displayed from the HDMI video link, together with the audio clock rate that will actually be generated from these values and the incoming pixel clock. For a properly functioning HDMI audio system, this sample rate should of course match that specified in the audio info-frame.
Other source tests are a CEC ping to determine what other CEC devices are on the video network, and an HDCP test to see how many downstream HDCP devices that are supported by the source in a HDCP repeater video network.
A pass-through mode may be enabled that allows video to be passed through the Quantum Data 780B “as is” while being examined, or enables 4K inputs to be downscaled to 1080p (CEA or SMPTE format) for monitoring on a 1080p capable external monitor.
HDMI / DVI Sink testing
One of the primary functions of the 780B HDMI video tester is to generate video test images and audio samples for presentation on a display (sink) to verify that the sink is operating correctly. The 780B augments this most basic function of a video test pattern generator with additional tests for the EDID, HDCP and CEC.
As a video generator, the 780B can output user selectable DVI or HDMI format outputs. Colour space can be switched between RGB, YCbCr 4:2:2 and YCbCr 4:4:4 at the touch of a button on the touchscreen. Similarly, colour depth can be switched between 8, 10, 12 and 16 bit. All common CEA formats - 480p, 480i, 576p, 576i, 720p, 1080p, 1080i and 2160p (4K) are supported as well as VESA formats for DVI testing. With each format, the frame rate can also be adjusted from 24Hz for Blu-ray through 50/60Hz and on to 120Hz maximum.
There are many test images supplied with the 780B. These range from colour bars, checkerboard patterns, black and white pluge, zone plates, colour and black/white ramps through to user uploaded bitmaps. There are also some optional test images for ISF and THX testing applications.
3D video generator is also supported with Side-by-Side (half and full), Top-and-bottom and Frame packing modes of generating 3D images all supported.
Audio test generation is also supported. Audio test sounds are supported both in the main HDMI video stream and in the ARC (Audio Return Channel). There are also optical and SPDIF connectors on the 780B on which the audio can also be output. All forms of audio are supported – PCM, Dolby, Dolby Digital Plus, Dolby True HD, DTS and DTS-HD. In the PCM audio mode, sample rate, word depth, volume frequency and channel allocation are all programmable. This simplifies the testing of surround sound audio systems.
As well as sending video and audio to a sink, the other common requirement desired by an installer is to read the EDID to determine the displays declared capabilities. The 780B is able to read and decode the EDID of an attached display, allowing useful information such as the preferred native timing to be easily extracted. This information may be stored as a report that can then be uploaded to a PC. Read EDIDs may be stored on the 780B and recalled to be used on the receiver port to allow the 780B HDMI video tester to emulate a display whose EDID has previously been captured. Saved EDIDs may be transferred to/from a PC, allowing test EDIDs to be shared between a team of installers.
An HDCP test is provided that tests the HDCP capability of the attached display. This shows the HDCP capability of the display (Bcaps register) as well as Aksv, Bksv and repeating Ri checks. A pass/fail indication indicates if the HDCP function is working correctly.
Like with the source tests, there is a CEC ping test to find other CEC devices on the video network.
HDMI / DVI Cable test
The cable test is designed to test the HDMI link between the input and output HDMI connectors. This could be a cable, but it could also include an active cable extender, AV receiver etc. The test is far more comprehensive than an electrical connectively test. The voltage on the 5V connection is measured to make sure it is within the HDMI specification. Hotplug, CEC and DDC are all tested with real signals. Most importantly, the video connections are actually tested by sending HDMI video with different formats over the link and the resulting pixel errors counted. A pseudo random bit pattern (being the most challenging for a video link) is used at 2160p30 (4K), 1080p60 (8 and 12 bit colour), 720p60 and 480p60. In this way a cable can be properly qualified to determine the highest video rate that the cable can support.
HDMI / DVI Link testing
A link test examines the control links in the HDMI connection: The DDC, 5V, Hotplug and CEC. The link analyser captures and logs (timestamps) all the activity on the link. So the engineer will be able to see how long it takes hotplug to be asserted after 5V is applied, and then how log (and the detail of) the subsequent EDID read. If ARC is supported, all the CEC activity related to the discovery and playback of audio on the ARC will be captured and shown. If HDCP is enabled, all the HDCP transactions will also be captured and shown. Captures can be saved and transferred to a PC for later analysis.