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14 APPENDIX C: TYPICAL AUDIO LATENCY VALUES
The back to back latency between two IQOYA X/LINK devices depends on the selected audio format, the network quality,
and the enabled functionalities (backup, half/full duplex, FEC).
See the table underneath for maximum latency values in half-duplex, using neither failover configurations nor FEC, with the
jitter buffer size set to 0, and with an optimized network.
Audio Format
PCM
MPEG Layer II
MPEG Layer III
AAC-4 LC
AAC-4 LC+SBR
AAC-4 LC+SBR+PS
AAC-4 LD
AAC-4 ELD
Opus
microMPX
320 to 576 kbps 192
All measurements taken on stereo samples at
Impact of the processing granularity
Add about 4 ms to the latency each time the processing granularity is increased by 1ms.
Impact of the network on latency
Latency highly depends on the quality of the network. Network jitter and packet loss typically have a direct impact on latency.
●
Network jitter compensation is achieved by buffering audio data on the decoder. A good quality network generally
offers a low jitter, then requiring low buffering on the decoder, which means a low increase of latency. But a network
with a high jitter requires increasing the decoder buffering accordingly, leading to a significant increase of latency.
●
In case of packet loss on the network, it is necessary to enable an FEC, which allows recovering lost packets thanks
to redundant frames. FEC increases the latency.
Impact of features on the latency
The amount of features used in IQOYA directly impacts the latency. For a given audio format, the lowest latency is obtained
in half duplex mode, with no backup defined and no FEC. As soon as one of these features is used, the latency increases a
bit.
Bit rate
(processing granularity set to 1ms)
24 bits, 48 kHz
256 kbps,48 kHz
128 kbps
256 kbps
96 kbps
56 kbps
160 kbps
160 kbps
256 kbps
kHz
IQOYA X/LINK-MPX user manual
Latency
13ms
90ms
152ms
105ms
210ms
251ms
51ms
45ms
73ms
(processing granularity set to 4ms)
Description
Valid for audio or MPX
aka HEv1
aka HEv2
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