Setup for Simultaneous Interpretation of Talks

If your channel would like the c3lingo team of interpreters to translate talks into other languages, please get in touch through Rocket Chat (, #lingo) or email (, and set up your production tech as described on this page.

In order for the interpreters to be able to do their work, two things need to be set up: audio and video from the studio/channel needs to be sent to the interpreters, and audio from the interpreters needs to be transported to the studio to be inserted into the stream.

The studio/channel should provide a stream or video conference where interpreters can hear and see everything that is going out over the stream, before it goes out. Ideally, they can also see and hear what is about to happen. In previous events, being able to see the video mixer multiview and hear the monitor sound (instead of the final mix) was really helpful.

The stream should either be viewable with common desktop clients (VLC, ffplay, …), or should work in a browser. Both low-latency RTMP streams as well as a Jitsi or BBB have been used successfully.

If you're planning to use Jitsi or BBB for production, consider adding the interpreters to that Jitsi/BBB as well. In that case, they would only listen there, but would be muted and have their camera turned off.

If you're using a local setup with an audio mixer, you can also feed the floor audio into mumble, since mumble automatically provides an N−1 setup (the client will not hear themselves).

c3lingo strongly prefers that you take the translated audio from This ensures that all interpreters have a tested setup, and that they can switch between channels/stages easily. Using this also reduces the on-boarding work that c3lingo organisers will have to do for each team member. c3lingo will set up Mumble channels for your channel/studio as needed. On the c3lingo Mumble server, random visitors will not be able to speak in the mumble channels (virtual interpretation booths) and all interpreters are given appropriate access rights as they join the team.

The translated audio channels should be set up so that the original audio is audible whenever the interpreters are not speaking. In past events, an automatic ducking setup with an ffmpeg filter complex has worked really well for that. This setup allows interpreters to leave parts of the talk untranslated, for example, when the speaker is reading out a quote in the language that is being translated to, or when a video is being played.

Ducking should not be too aggressive. The maximum volume reached when there is silence from the interpreters could stay slightly below full level, and the increase to full volume should be slow.

The recording of the translated audio should have no original audio mixed in; for the recording, the mixing will happen in the post-processing stage.

The most important support that c3lingo asks for is this: As content organisers, do your very best to make speakers submit their materials in advance, and give c3lingo access to your collection. if you don’t run such a collection, ask speakers to upload to (*) – in any case, please emphasise to your speakers that this is important and send a reminder ca. 2 days before the talk if necessary. If you’re referring your speakers to, you can check there whether materials were uploaded, even though you won’t see the uploaded content.
For many talks, it is extremely helpful for the interpreters to review this material ahead of time, for example to make sure that specific words and terminology are translated correctly and names of people and institutions are not missed.

(* Use of requires that the event is published as Fahrplan XML – we assume that a central XML file will be published and will feed it to the site.)

Materials include • slides, • slide notes, • questions that panel moderators intend to ask, • scripts for pre-written talks (this is important, scripted talks are much harder to interpret), • any texts that will be read out as part of a talk … Anything the speakers consider helpful is welcome.

  • events/jahresendveranstaltung2021/c3lingo.txt
  • Last modified: 2021/11/28 23:03
  • by sebalis