Lennart Poettering wrote:
On Mon, 15.06.09 16:36, Jonathan Abrams ([email protected]) wrote:
Hey folks,
I've been having a couple issues with RTP. I'm using pulseaudio 0.9.15.
For some background, I have a system set up where I have one machine
running module-rtp-send, attached to the monitor of a null sink. The
receiving machine has module-rtp-recv loaded, that then attaches to a
null sink. This allows me to hook up applications to RTP as if it were
any other device. So far so good!
Here are my problems:
1) When I make a connection and start to play some audio there's an
approximately 5 second delay before audio is heard on the receiving end.
These 5 seconds also appear to be 'lost', not just buffered. What could
be causing this? Is this a known issue or a bug, or just how it normally
works? Is there a workaround or fix?
Uh. This might be the SAP pickup time. Dunno.
2) Because I sometimes need to connect the RTP stream (being passed
through a null sink) to a device instead of an application, I use a
'pacat -r -d <deviceid1> | pacat -p -d <deviceid2>' loopback. This
will
The clocks of those two devices don't need to be in sync, so this must
dropout sooner or later.
But why are doing this anyway? You can just load module-rtp-recv on
the right sink and have it deal with the clock deviations.
Lennart
Thanks very much for the response Lennart.
The reason we are doing this is because we are creating an audio
management system that manages audio devices on different logical audio
'buses'. In most cases, applications can connect to a logical bus by
connecting to the source/sink that represents the bus on that host. In
order to use RTP this way, we need to make it appear in pulseaudio as
sources/sinks, (not as source-outputs/sink-inputs). Tying RTP streams to
null sinks works fine for the most common use case (connecting an
application to a 'bus'), but we also need to be able to 'bridge' buses.
This is where connecting sources directly to sinks is required. We are
doing this using pacat and pipes. But obviously this is insufficient due
to the source and sink having different clocks. The FAQ on the
pulseaudio website recommends using the pacat pipe method for connecting
a microphone directly to speakers. Does it work in that scenario because
the microphone and speakers use the same clock? Is there another way to
connect a source to a sink that is clock agnostic?
Thanks again,
Jonathan
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