Knowledge Base

Opus Encoding

Last Updated: Feb 20, 2019 11:44AM GMT


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 modelling) 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 for version 3. 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 standardised since September 2012, and already Mozilla supports 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 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 opus.


Importing Audio

By default ALL audio files are converted to Audio Notetaker's internal format, Opus, on import. You can disable this;  go to App Menu > System > Settings > Audio Files. 



We also use Speech Quality Conversion  (Fast Conversion on Mac) as default which doubles the conversion speed, creating smaller files, 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.You can set the convert to Music Quality Conversion which will take longer to convert but will produce better quality, larger files.

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