LiveU manufactures equipment to conveniently and correctly deliver audio and video data from a mobile camera source (connected to a LiveU field unit) to an accompanying server (known as a LiveU transceiver). From this server multimedia content can be extracted, either through SDI, or by encoding it and sending it upstream through RTMP.
There are some cases where using the LiveU transceiver equipment to send an RTMP stream to an RTMP server might cause the audio and video to become desynchronised:
- When network conditions are poor.
This is the most common case where this can happen. Temporary network failures may happen on the Internet depending on the quality of your connection, your ISP, and where the RTMP data is being sent to. If you are at risk of experiencing network errors then the longer the broadcast lasts, the more likely this is to spontaneously happen.
- If the receiving RTMP server restarts.
The main case where this happens is in between events. Screen9 starts a new server for each separate live event (as seen in the account console). However, if the LiveU field unit has not been set to stop and restart sending data, the LiveU server would treat this case in the same way as a temporary network error.
Please note that these issues are not the result of the server software used by Screen9, but rather by the specific RTMP implementation in LiveU servers. If your live stream does go out of sync, it can generally be fixed on your LiveU field unit by turning broadcasting off and on.
To avoid getting a live stream that's out of sync, you can do one of the following:
Send video via an alternate encoder.
LiveU guarantees that the SDI output of a LiveU server is a perfect copy of what the LiveU unit receives as its audio/video input. If you can connect this output to a computer running an alternative encoder you can configure the encoder to send the stream to Screen9 instead. Wirecast is an example of an encoder that can be used in this case. For how to set up your encoder, refer to our other articles on live streaming.
Ensure optimal conditions for the LiveU equipment
While these steps are not guaranteed to result in a correct stream, they do minimize the currently known risks.
- Make sure that the LiveU server has a good network connection.
Temporary network problems between the LiveU server and the RTMP server can cause the audio and video to desync.
- Restart the ingest process from the LiveU sender between every Screen9 live event.
This can be done from the interface on the LiveU unit (e.g. the top left on LU400 units). Not doing this could cause the LiveU server to behave as if poor network conditions occurred, resulting in desynchronisation.