{"id":1836,"date":"2022-03-03T22:20:34","date_gmt":"2022-03-03T22:20:34","guid":{"rendered":"https:\/\/www.brucewiggins.co.uk\/?p=1836"},"modified":"2022-03-10T15:29:03","modified_gmt":"2022-03-10T15:29:03","slug":"stereo-to-ambisonics-using-uhj","status":"publish","type":"post","link":"https:\/\/www.brucewiggins.co.uk\/?p=1836","title":{"rendered":"Stereo to Ambisonics using UHJ"},"content":{"rendered":"\n

Back in 1983, Michael Gerzon presented a 2, 3 or 4 channel encoding system called UHJ where the 1st two channels are stereo compatible Left and Right signals. This was, in the 4-channel incarnation, a lossless transcoding of the W, X, Y and Z channels of Ambisonics. If only the first two channels are kept, then horizontal Ambisonic surround is still able to be extracted, albeit with less isolation between the resulting channels (much like Dolby Stereo used in cinemas from 1976).<\/p>\n\n\n\n

I won’t bore you with the equations and maths of the system, but Gerzon’s original paper can be found at http:\/\/decoy.iki.fi\/dsound\/ambisonic\/motherlode\/source\/11730.pdf<\/a> <\/p>\n\n\n\n

To cut a long story short, I’ve made a UHJ decoder plug-in based on Gerzon’s paper above, as there isn’t one currently available that works in the same way:<\/p>\n\n\n\n

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Screenshot of the WigWare UHJ Decoder\/Transcoder JS Effect Plugin<\/figcaption><\/figure>\n\n\n\n

Although UHJ encoded material works best (a discography of UHJ releases can be found at http:\/\/www.surrounddiscography.com\/uhjdisc\/uhjhtm.htm<\/a>), any two-channel recording can be fed into the decoder and either a square\/rectangle decoding can be produced, or the B-Format for decoding using another plug-in. Do note that the ‘shelf-filters’ recommended for UHJ are different from the ones used for ‘standard’ Ambisonic B-Format decoding.<\/p>\n\n\n\n

There are other UHJ implementations available, but this plug-in has a few features not available elsewhere:<\/p>\n\n\n\n