Knowledge Base

Reference Guide: 2.3 Opus Encoding

Last Updated: Aug 24, 2016 09:50AM IST


Audio Notetaker now records in the standardised Opus audio encoding system (standardised by the Internet Engineering Task Force - IETF). It is particularly suitable for Audio Notetaker as it combines technology from both audio (perceptual) and speech (voice modeling) encoders, giving the best possible quality for speech whilst coping perfectly with general audio as well. It uses Variable Rate Coding, which means that if there's not much sound to encode, it doesn't waste space encoding it - perfect for Audio Notetaker which doesn't care if the encoding rate is fixed or not. So all in all, it gives the best file-size/quality tradeoff possible. This will make quite a difference when uploading your ran files to and from the Cloud, attaching them to emails etc.

But that isn't the only reason we have adopted it as our internal audio format. Unlike all other audio compression standards, it has a royalty-free license scheme. This means there are no barriers to anyone and everyone adopting the standard in their web-browsers, operating systems etc. Indeed, it has only been standardized since September 2012, and already Mozilla support it in Firefox, and Cisco and Google are supporting it in various products. Unlike the current inconsistent support for the various audio formats across browsers, operating systems & media players, we expect Opus to be fully supported on all of these within a year or two. This means the audio in your ran files will be always be usable without further conversion - even if right now you may have to convert to wma/m4a on export if your favourite media player doesn't yet support it.



By default all files are converted to Audio Notetaker's internal format, Opus, on import. You can disable this in App Menu → System → Settings → Audio Files.

We also use Speech Quality conversion as default which doubles the conversion speed and makes little difference to the quality of your recordings. You may find that the quality of recordings of more subtle sounds such as musical instruments is affected. Speech Quality conversion is on by default but you can change it to Music Quality using the Import Button Dropdown menu → Audio Quality or in App Menu → System → Settings → Audio Files.

See Converting Imported Audio for more information.

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