[pulseaudio-discuss] native-protocol-tcp vs esound-protocol-tcp

[Tanu Kaskinen]

On Mon, 2010-05-10 at 22:46 +0700, Antoine Martin wrote:
> Are there any reasons to prefer native over esound?

The one that I know is that the esound protocol doesn't provide latency
information, which makes reliable lip-synced video playback impossible.

> Does anyone know what the bandwidth requirement is for either of these 
> protocols?

It depends mostly on the number of channels, sample format and sample
rate. For the most common audio streams the raw audio takes about 1.4
Mbit/s. On top of that there's the protocol overhead, which should be
rather small in comparison for either protocol.

> Is there a way to reduce the bandwidth used if I know in advance that 
> the line is not going to be able to sustain it? (via some kind of 
> filter? for my use case, horrible sound quality is better than getting 
> disconnected! think <512Kbit/s)

You can run pulseaudio servers locally on the clients and create tunnel
sinks. You can configure the tunnel sinks to use a lower-quality stream
format (e.g. mono 22050 kHz -> ~350 kbit/s).

> Also, I seem to be missing something on native-protocol-tcp, because I 
> can do this with esound:
> 1) Spot my desired sink:
> $ pacmd list-sinks | grep -C 1 name:
>      index: 0
>      name: <alsa_output.1.hdmi-stereo>
>      driver: <module-alsa-card.c>
> --
>    * index: 1
>      name: <alsa_output.0.analog-stereo>
>      driver: <module-alsa-card.c>
> 
> 2) Start an esound tcp connected to that sink:
> pactl load-module module-esound-protocol-tcp port=12345 
> auth-cookie-enabled=0 sink=1
> 
> 3) Now, I can't seem to play anything (any ideas why?):

No ideas. I'm not familiar with esound.

> esdcat -s localhost:12345 < some_file.wav
> echo $?
> 1
> Not exactly forthcoming with the cause of the problem, but at least 
> esound is listening on that port.
> 
> Whereas with native, I can't even load the module if I specify a sink:
> $ pactl load-module module-native-protocol-tcp port=12421
> 32
> That worked!
> $ pactl load-module module-native-protocol-tcp port=12422 sink=1
> "Failure: Module initalization failed"
> Hmm

module-native-protocol-tcp doesn't take a sink argument. The modules and
their arguments are documented on http://pulseaudio.org/wiki/Modules

> Finally, is there a way to change the auth-cookie on the fly? 
> (with/without disconnecting clients if possible)
> So that I can revoke the access that I had previously granted to a 
> remote user.

I don't see other way than revoking the ssh access for the evil user
altogether.

-- 
Tanu Kaskinen