Talkback Audio Format Specifications

Haivision's InStream software player provides a talkback audio stream to the encoder. The InStream player is available either with the Furnace IP Video System v6.x or as a mobile application. For more information, see the InStream User's Guide or the InStream Mobile (iOS or Android) Quick Start Guide available through Haivision's Download Center.

The following specifications are provided for customers or system integrators who choose to develop their own applications to send talkback audio to Haivision encoders:

1. Audio data in each payload is uncompressed PCM digitized audio. There is no encoding/decoding involved.
2. Transmitted over unicast UDP (only port 9177) to the Makito X.
3. Audio sampling rate = 22.05 kHz (44.1 divided by 2).
4. Each audio sample is a raw 16-bit PCM (LSB First).
5. Mono audio only.
6. Each UDP packet contains 440 samples.
7. UDP payload is 880 bytes minimum. (Anything beyond the 880th byte is discarded.)
8. There is no audio mixing; one audio channel at a time: first in / first served. The talkback application software should be equipped with "push-to-talk" type of feature.
9. The talkback service locks out all other talkback sources for 500-ms period during which time only a single identified source may be played.
10. Once an end-point has acquired the talkback interface, it maintains control of the talkback interface until audio is no longer streamed to the Makito X for 500 ms.
11. If the audio input is disconnected, the application does not need to send filler zero (silence) bytes, because talkback on the Makito X inserts zeros (silence) to maintain the output audio clock.
12. Talkback audio is output over the mono analog "Audio Out" connector on the Makito X encoder.