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Real-time Virtual Appliance

High-Level Summary

This release adds HTTPS support for the appliance REST APIs, with the ability to upload your own security certificates. TLS 1.2 and 1.3 are supported; certificates and keys that are uploaded should be in the PKCS #8 format.

The following languages now support advanced punctuation: English (en), German (de), Spanish (es), French (fr), Dutch (nl), Danish (da), Turkish (tr) and Malay (ms).

It is recommended that customers on previous releases upgrade to this version.

Important Notices

The legacy V1 API that the Real-time Virtual Appliance currently supports will be discontinued in a future release. We recommend that customers familiarise themselves with the configuration object as described in the Speech API Guide. Future notices will be provided to announce the end of life of the V1 API, and provide detailed instructions on migrations to the V2 API.

What's New

  • HTTPS for Management, Monitoring and Speech APIs
  • For the English language model, numbers less than 10 are output as words ('zero', 'one', 'two', etc)
  • Improved localised spellings for en-GB and en-US output locales

Issues Fixed

The following issues are addressed since the previous release:

Issue IDSummaryResolution Description
REQ-12489The en-GB output locale sometimes outputs en-US spellingsThe latest rebuild of English (en) addresses this issue.
REQ-13430Virtual Appliance conflict of internal (docker) and customer subnetsA smaller subnet is now used to reduce the likelihood of conflicts.
REQ-12405English Transcription Includes Russian WordsThe latest rebuild of English (en) addresses this issue.
REQ-12551Invalid Character in RTA PartialsInvalid characters were introduced into the English (en) language pack for the previous release; these have now been removed.
REQ-10688Memory leak on client disconnect with pending buffered audioClients sending data to a worker faster than it can be processed could cause a memory leak; this has now been addressed.
REQ-11812Transcript and word elements from RT can contain ˻ as a wordA rebuild of the English (en) language model has fixed this issue.
REQ-11829No worker available in RTVA in unclean disconnectsThis was caused by a race condition that has now been fixed.
REQ-12541Combo words RTA 3.2.2 which are not present in RTA 3.2.1The previous release introduced a problem with the English (en) model where seperate words were sometimes joined together. This has now been fixed.
REQ-13201Transcriptions replace the word "Sigma" with the symbol "σ"This has now been fixed in the latest English (en) model
REQ-13690Sessions that use large custom dictionary word lists may experience disconnectsEnsure that you use a WebSocket ping/pong timeout of 60 seconds on your client

Known Limitations

The following are known issues in this release:

Issue IDSummaryDetailed Description and Possible Workarounds
REQ-1409Proteus HCL with <unk> causes out of memory errorA custom dictionary list that contains the word '' causes the worker to crash.
REQ-7549Memory leak affecting gRPCThere is a small memory leak in the gRPC Python server (
REQ-10160Advanced punctuation for Spanish (es) does not contain inverted marks.Inverted marks [ ¿ ¡ ] are not currently available for Spanish advanced punctuation.
REQ-10627Double full stops when acronym is at the end of the sentenceIf there is an acronym at the end of the sentence, then a double full stop will be output, for example: "team G.B.."
REQ-11087Additional white space appearing before the very last end of sentence punctuation character.Its been observed that additional white space can occur before a full-stop '.' in some transcripts. This can be parsed and removed by a post-processing step if necessary.
REQ-111353.2.0 introduced unwanted hesitations in transcripts.Due to changes in the way that training data is now ingested to improve the accuracy of spontaneous speech for English (en) there is a greater likelihood that hesitations will be included in the output transcrtips. We plan to support a hesitation filtering capability in a future release for customers that do not want to see hesitations on transcripts.
REQ-11792Speaker change token positioning is incorrectWe are aware of a consistent mis-placing of the speaker change token after the first word of the new speakers' sentence rather than before it.
REQ-12202High memory usage when using custom dictionaryIt has been observed that when using custom dictionary an additional 800-1700MB of memory is required (depending on the size of the wordlist used).

Supported Platforms

Virtual Appliance image (OVA) for installation on:

  • VMware ESXi 6.5+ or VMware Workstation Player.
  • VirtualBox 5.2+
  • Amazon EC2

See the Installation and Admin Guide for details on the minimum specifications for the VM. The maximum number of concurrent jobs (maxworkers) that you can run on a single appliance is 32.

Form Factors

There are four variants of the Real-time Virtual Appliance.

VariantImage SizeMax. Disk SpaceLanguages
mini16GB40GBen, de, es
midi27GB60GBen, de, es, fr, ko, ja, nl, pt
maxi45GB80GBen, de, es, fr, ko, ja, nl, pt, it, da, pl, ca, hi, ru, sv
plus75GB80GBen, cmn, no, ar, bg, cs, el, fi, hu, hr, lt, lv, ro, sk, sl, tr, ms

Upgrade Path

Remove the license from your old appliance (see the Admin Guide), then re-import the new OVA and configure networking as per the Installation and Admin guide. You will need to re-apply the license code you have once the OVA has imported.


Upload the OVA to VMWare ESX, VMWare Workstation Player, or VirtualBox. See the Installation and Admin Guide for more information.