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How to configure your encoder?

General encoder setup

In Clevercast, you can find the necessary info to configure your encoder on the 'Broadcast' tab of the event page.

Please follow our broadcast guidelines as much as possible. This section lists possible encoder configuration for the different broadcast protocols. We also have a (non-exhaustive) list of example configurations.

Note: Clevercast currently delivers all multilingual live streams (including T@H and captions) with a framerate of 25 fps and keyframe interval of 2 seconds, no matter what framerate your broadcast contains. Therefore, we strongly recommend to use a framerate of 25 fps and keyframe interval of 2 seconds. If you use a higher framerate and not all frames are delivered to Clevercast in time (eg. network connections, insufficient bandwidth at the event location) this may cause the floor audio to go shortly out of sync.

Tip: when testing your broadcast, make sure to first set your event status to Preview. If the event status is Inactive or Ended, your broadcast will not be processed.

Setup per broadcast protocol

Single-language live streams

Any SRT or RTMP encoder can be used.

Single-language broadcasts for T@H and captions

Any SRT or RTMP encoder can be used. If possible, use a framerate of 25 fps and keyframe interval of 2 seconds in your broadcast (otherwise Clevercast will convert the framerate to 25 fps, see above).

Note: there’s a known issue for T@H that only occurs if you are broadcasting a still image or animated intro with variable bitrate (VBR) when you initially set your event to Preview, which may cause translated audio to be slightly ahead of the floor.

Multilingual broadcasts

If you are broadcasting multiple audio streams along with the video stream, make sure to select a broadcast protocol that fits your encoder (see options below). To configure your encoder, see the settings on the Broadcast tab.

Multilingual SRT broadcasts

The SRT protocol's allows you to add multiple (stereo) audio tracks to a single video broadcast. This is being supported by a growing number of encoders (see example configurations).

The possible number of languages depends on your SRT encoder. Clevercast allows each stereo track to be used for two languages in mono (L+R channels). Therefore, every SRT encoder can send at least two languages.

Use the following SRT-specific settings on the Broadcast tab to configure your encoder:

  • SRT passphrase: the passphrase for authentication.
  • SRT Key Length: The level of encryption (AES 128 by default).
  • Languages per track: the number of languages inside each audio track, as sent by your encoder
    • Set it to 1 if each audio track contains a single language (in mono or stereo). In this case, the number of tracks sent by your encoder should equal the number of languages.
    • Set it to 2 if your encoder is sending stereo track(s) containing two languages (panned L+R). The number of audio tracks sent by your encoder should be half the number of languages (e.g. 8 languages -> 4 stereo tracks with 2 languages).
    • Exception: when using vMix set Languages per track to the total number of languages, since vMix sends a single audio track with multiple channels.
SRT broadcast with two languages in a stereo channel

Sending two languages in a single stereo channel (languages panned L+R) is possible with any encoder that supports SRT (e.g. OBS Studio, Wirecast, vMix ...). In that case, Languages per track should be set to 2.

SRT broadcast with more than 2 languages

See this list with examples of soft- and hardware encoder configurations for more than two languages. The list is not exhaustive. If you have another encoder and would like more info on how to configure it, please contact us.

Broadcasting more than 12 languages is currently only possible with hardware encoders, like Haivision’s Makito X or Intinor Direct Link. Hardware encoders are also much more reliable than software encoders. For more encoder brands, see the SRT Alliance’s members page.

Multilingual RTMP broadcasts

With RTMP, the options for sending a multilingual broadcast are limited. First of all, the broadcast must originate in Europe. Our RTMP ingest hubs on other continents currently don't support multilingual broadcasts.

RTMP broadcast with two languages in a stereo channel

Sending two languages in a single stereo channel (languages panned L+R) is possible with any RTMP encoder (see examples. In that case, Languages per track should be set to 2 (on the event's Broadcast tab).

RTMP 4.0 or 7.1 surround broadcast using OBS Studio

OBS Studio is capable of broadcasting a video with multiple audio channels over RTMP through its support for surround sound audio streams. See our configuration guide for more info.

RTMP broadcast with a separate video+audio stream per language

If you only need a couple of languages and have sufficient outgoing bandwidth, it is possible to send a separate RTMP broadcast (video+audio) for each language. This is possible with any encoder. In that case, you are responsible for starting the different language broadcast at the same time (so they are in-sync).

Note: this is currently not part of our default plans. If you need this, ask for a custom plan.

Relay from third-party platforms

Clevercast supports platforms and applications that let you send an RTMP or SRT broadcast. For example, in-browser studios like StreamYard, Restream.io and Lightstream, and several online meeting platforms like Zoom and Cisco Webex support RTMP restreaming.

Since the streaming servers of most third-party platforms (e.g. Streamyard, Zoom, WebEx) are located in North America and only support the RTMP protocol, make sure to choose RTMP from North America, Streamyard, Zoom... as broadcast protocol.

Known issue for relay from Zoom

The first packets of a broadcast from some third-party platforms, in particular Zoom, may take a little longer to get to Clevercast. On some very rare occasions the initial broadcast may be unreliable, leading to it not being accepted by Clevercast. If that were to happen, just keep your broadcast running and reset the event to Inactive, then set it Preview again.

Main and backup broadcast

For most broadcast protocols Clevercast supports a fully redundant setup, which allows you to broadcast to a main and backup server on different geographical locations. Use the settings in the Backup Broadcast panel to send the same broadcast to both servers simultaneously. In that case, Clevercast player will detect if one of the streams is down and automatically switch to the backup stream, without your viewers having to refresh the page.

Exception: T@H and transcribed captions

Livestreams with Translate@Home and captions through manual transcription currently form an exception. Even though Clevercast supports broadcast and live stream failover, this is not yet automated for the T@H audio and transcribed captions. So after a failover, you won't hear a translation or see a caption, before the resp interpreter(s) and transcriber(s) have switched from the main rooms to the backup rooms.

For these 2 special cases we recommend not switching to the backup broadcast unless the main streaming server is actually down. It is extremely rare that the main broadcast fails. If it were to happen, we think it would be better to put the event status shortly on pause for a controlled failover, so you can start the backup broadcast and all interpreters and transcribers can switch to the backup rooms. If you would like to prepare for this, provide the backup room links to your interpreters in advance and make clear arrangements on what to do in case of a controlled failover.

It is our intension to add T@H and transcription failover to Clevercast in one of the upcoming upgrades.