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Real-time Virtual Appliance

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.

Currently, Speechmatics supports 2 python libraries for use with our Real-time products. smwebsocket-py is recommended for use for the Real-time Virtual Appliance only, and speechmatics-python is recommended for use in both our Real-time Container and our Real-time Virtual Appliance. In a future release we will exclusively support speechmatics-python as our preferred Python library. We recommend you familiarise yourself with this library and use wherever possible. Please contact if you require access to this library.

What's New

  • New language packs for Dutch and German
  • Profanity tagging in English

Issues Fixed

The following issues are addressed since the previous release:

Issue IDSummaryResolution Description
REQ-15418Custom dictionary with splitting characters gets incorrect pronunciationWhen using words with splitting characters in a Custom Dictionary (for example covid-19) where a number follows a word we now have the correct pronunciations created. Splitting characters include ["-", "_", "/", "<", ">", ":", " "]. This is for all languages
REQ-11426When there are two speakers in German, the second speaker is sometimes not transcribedThis is now resolved in the latest German release
REQ-11960Transcripts are blank for some German audio filesThis is now resolved in the latest German release
REQ-12791Some German numbers are not transcribed accurately or are missingThis is now resolved in the latest German release
REQ-12792Some German transcripts are missing wordsThis has now been resolved in the latest German release
REQ-15870In the global English language pack the word "check" with British output locale is always transcribed as "cheque"This is now fixed in the English language pack

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 transcripts. 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).
REQ-16256Heavy usage of RAM when swapping between 8kHz and 16kHz inputWhere multiple persistent workers are configured with Custom Dictionary that swap between 8kHz and 16kHz input, this can cause a memory leak that causes the container to crash. If this is a workflow used it is recommended to consistently check the memory usage of the appliance, and restart it where necessary

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 30.

Form Factors

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

VariantImage SizeMax. Disk SpaceLanguages
mini14GB40GBen, de, es
midi26GB60GBen, de, es, fr, ko, ja, nl, pt
maxi42GB80GBen, de, es, fr, ko, ja, nl, pt, it, da, pl, ca, hi, ru, sv
plus46GB80GBen, 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.