Lowest possible latency achieved? Is bellow 2 seconds doable?

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May 7, 2023, 10:03:51 AM5/7/23

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I need the lowest possible latency from analog input to DAB (yes, it is important in my use case).

Best would be bellow 1 second, better in the sub 500ms range.

I achieved about 2.2 seconds by setting dabmux to:

------

subchannels {

sub-p1 {

; MPEG

type dabplus

bitrate 128

id 1

protection 3

inputproto zmq

inputuri "tcp://*:9001"

zmq-buffer 7

zmq-prebuffering 4

---------

Lower does not work.

I have tested my alsa configuration, to rule out latency from the audio interface. It is bellow 30ms.

Also I set dabmod to:

------

[input]

transport=zeromq

max_frames_queued=100

---------

Are there any other ways I can lower latency?

If I turn off dabmod it stops immediately.

If I turn off dabmux I get about 1.5 seconds till it turns off

If I turn off dabenc I get about 1.5 seconds till it turns off

doesn't add up really.

I tried to use IPC instead of tcp. Because chatgpt says it could be lower latency But does not work at all.

I tried edi. But thats slower.

ZMQ supposedly accepts settings like ZMQ_SNDHWM and ZMQ_RCVHWM to adjust buffer size, but that would need to be done somewhere in the apps.