Multi-Language Streaming FAQ
How many languages are possible per stream ?
Clevercast has no restrictions. So, it depends on the broadcast protocol and encoder you use.
- Translate at Home (T@H): unlimited
- SRT multi-track broadcast: 12 languages with OBS Studio, more audio tracks supported by other encoders (tested with 16 languages, see the Encoder Support section below)
- RTMP multi-channel broadcast (only supported by OBS Studio): 7 languages via 7.1 channels.
Which broadcast protocol should I use ?
That depends on your location, your encoder and the number of languages.
- Location: our ingest servers are located in Europe. If you are broadcasting from another continent, preferably use SRT which is reliable over long distances.
- Encoder, Languages: If you’re not using Translate at Home, you’re limited by the number of languages supported by your encoder. OBS Studio supports both RTMP (up to 7 audio channels) and SRT (up to 6 audio tracks, which you can use to send 12 languages by L+R panning). Other SRT encoders support more languages (see the Encoder Support section).
Should I use Translate at Home (T@H) ?
This depends on a number of things:
- Costs, health & safety: T@H doesn’t require interpreters to travel.
- Ease of use, deployment: T@H doesn’t require translator booths and in depth technical knowledge. It can be set up quickly.
- Production requirements: Don’t expect T@H to be on par with a multilingual production on site. If you need audio of the highest quality or a separate mix per audio channel, you should choose an on-site production with an SRT multi-track or RTMP multi-channel broadcast.
- Audio quality: With T@H, the translated audio quality depends on the connection and equipment of your interpreters (see our requirements and best practices for interpreters).
- Number of languages: T@H supports any number of languages. With a multilingual broadcast you are limited by the number of tracks or channels that your encoder supports.
Are there broadcast guidelines or restrictions ?
Our Broadcasting Guide helps you configure your encoder. If you’re unable to follow our broadcasting guidelines, please test in advance and let us know if you experience issues.
Additional guidelines are available for broadcasting multiple audio tracks with SRT and broadcasting multiple audio channels with OBS Studio.
Having trouble broadcasting or streaming? See our troubleshooting guide.
Can Clevercast do multilingual pseudo-live streaming ?
Yes. This allows you to stream a recorded video with multiple languages as if it were a live stream. Viewers will not see any difference.
How does multilingual live streaming work ?
The incoming streams are transmuxed and transcoded in realtime by Clevercast to streams that can be delivered using HLS. We use global CDNs (Amazon CloudFront, Akamai, Fastly) for global delivery, so viewers anywhere in the world will receive the stream from a local server.
Note: since global CDNs have substantial price differences per region, we also offer the option to only deliver the stream through European server regions. For high volumes of data traffic (20 TB or more) you can request a custom price based on the estimated location of your audience.
How do viewers choose their language ?
You embed our video player on your website(s). The player on your site will automatically show all available languages through a dropdown menu (headphone button). Your viewers can use it to select their preferred language. This works on all (modern) browsers and devices (Android, iOS).
Do you support adaptive streaming (multiple resolutions) ?
Yes. Clevercast does realtime server-side transcoding of your broadcast into multiple video resolutions which are all available to the player. A typical adaptive set is 1080p, 720p, 480p, 360p and 240p. For each viewer, Clevercast player will automatically choose the best possible resolution and switch to a different one if necessary (depending on screen size, bandwidth, GPU, CPU).
How many concurrent viewers can watch the live stream ?
Unlimited. If you expect more than 100.000 concurrent viewers, please let us know.
Is it possible to simulcast separate language streams (eg YouTube, Facebook) ?
Yes, optionally. You can add any number of per-language simulcast targets to your Clevercast plan.
Can I limit the number of viewers ?
Clevercast player doesn’t limit the number of viewers. If our player is embedded, your website could do this instead.
We also have a webinar solution, where our player is hosted on a (branded) webinar page. This supports viewer registration or invitation and thus can limit the number of viewers.
Can Chinese viewers watch the live stream ?
The network of global CDNs in mainland China is separate from their global network, due to Chinese government regulations. Only companies with a valid Chinese business license have access to it. We don’t.
These global CDNs have other edge servers which are sufficiently close (eg. Hongkong) for high quality video streaming. But since the Chinese government requires all traffic to pass through their Great Firewall, this may cause traffic congestion in some cases. Therefore, we can’t guarantee the quality of experience of Chinese viewers.
Testing & trial accounts
What are the limitations for trial accounts ?
By default, trial accounts are limited to 480p video, 4 languages and 5 hours of live streaming. If you need more hours, send an email to firstname.lastname@example.org. In most cases, this won’t be a problem.
Don’t forget to turn off your encoder when you’re not testing. Preferably also set the event status to waiting or ended. If you don’t, it will be reset by Clevercast after 4 hours (for trial accounts).
How do I test with OBS Studio (or another encoder) ?
You can test Translate at Home by simply sending a video stream with mono or stereo audio.
If you want to broadcast multiple audio tracks or channels, you need an external device that maps the audio input to tracks or channels (NOT BOTH).
My live stream is not working ?
Make sure to follow our general broadcasting guidelines and our protocol-specific guidelines for Translate at Home, SRT multi-track and RTMP multi-channel. If you want to try out T@H, read our guide for interpreters.
Don’t forget to set the event status to Preview or Started. If you don’t do this, the live stream won’t work and T@H language rooms are not available.
For multi-track or multi-channel broadcast, make sure not to make these mistakes:
- Don’t mix tracks and channels. For RTMP multi-channel, your broadcast must contain multiple audio channels in a single track. For SRT multi-track, your broadcast must contain multiple audio tracks (with channels set to mono or stereo).
- For SRT multi-track, your broadcast must contain the same number of tracks as the number of languages in Clevercast. If you use SRT with OBS Studio, make sure to press the ‘Start Recording‘ button (instead of ‘Start Streaming‘).
- For RTMP multi-channel, your audio channel selection must be the same (eg 4.0) in your Clevercast event, input device settings (eg Blackmagic DeckLink) and OBS Studio Channels setting.
See our Troubleshooting page for more help. If nothing works, send us an email.
Translate at Home
A broadcast for Translate at Home must contain a single video and audio stream (mono or stereo). This can be sent with any encoder, in-browser studio or third-party solution that supports RTMP or SRT broadcasting (eg. vMix, Zoom). You can add any number of languages in Clevercast.
Stereo panning for 2 languages
If you only need 2 languages, you can send a stereo broadcast over RTMP or SRT with both languages panned left and right. This can be done with any encoder.
vMix supports RTMP and SRT broadcasts to Clevercast. But it currently doesn’t allow you to send multiple audio tracks. So you can only use it for stereo panning to 2 languages, or for T@H.
Ingest from third party solution like Zoom ?
Currently, Microsoft Teams doesn’t support this. It does support NDI output to your Teams client, which you could use to broadcast to Clevercast via an encoder within your LAN (eg Teams to OBS to Clevercast). This requires sufficient technical knowledge.
SRT multi-track broadcast
OBS Studio has support for 6 audio tracks. You can use stereo to pan two different languages L+R (if you do this, change the Languages per Track setting of your Clevercast event to 2). This way, you can stream 12 languages using 6 stereo tracks.
Other SRT encoders support 8 or more tracks. For example, the Intinor Direct Link and Makito X both support 8 stereo tracks, the Makito X4 supports 16 stereo tracks. With these encoders, you can also use stereo tracks to pan two different languages L+R (if you do this, change the Languages per Track setting in Clevercast to 2). For example, you can stream 16 languages using 8 stereo tracks.
If you have an SRT encoder and want to test interoperability with Clevercast, please contact us.
RTMP multi-channel broadcast
Currently only supported by OBS Studio through their surround sound feature, for up to 7 languages.
What are the requirements for translators?
Basically, they must be able to sent the audio stream to Clevercast without distortion or packet loss.
This can roughly be translated into the following requirements:
- Using a recent version of Mozilla Firefox
- A minimal bandwidth of at least 5 Mbps up and down.
- A wired connection to the internet! Even a good wireless connection with plenty of bandwidth may still cause audio distortion.
- Headset with noise cancelling for audio output and input.
- No excessive packet round-trip time. If packets arrive too late, the audio will be dropped or distorted. Our ingest servers are located in Europe, so translators in Europe will mostly be fine.
- A recent computer with sufficient CPU and memory.
The most important requirement is sufficient testing! Each translator should test in a situation that matches the live event as much as possible.
Below are some possible causes of issues during the live translation:
- Network congestion: if translators are in an intranet with much more traffic than during the test (eg. people viewing the live stream, multiple translators at the same location) this could cause problems (eg. dropped packets, audio distortion) that did not arise during testing.
- Wifi: don’t use Wifi if there is any way to avoid it. Even if it works during testing, it may still cause problems during the real live stream.
- Make sure that the sound from the microphone AND from the video stream goes through your headset. If the sound of the video stream goes through your speakers, this will certainly lead to interference.
- Clevercast allows viewers to hear a faded version of the original audio in the background of the translated audio streams. Don’t set this too loud: some speakers may sound louder in the original audio.