[pulseaudio-discuss] Crackling Audio in Pulseaudio RTP Stream

[Chris Beat]

On 19/02/2023 20:10, NicoHood wrote:
> Hey Sean
> as I said I've setup pulseaudio via paprefs. I've enabled the RTP receiver and the sender with a
> loopback device. Basically I've checked all 4 checkboxes in the paprefs RTP menu.
>
> And as I said, it also happens on the local host itself. I am also receiving (playing) the sound on
> the device that is the sender, via the loopback functionality. And thatswhy there is no lan/wifi
> issue, as it is completely local. But I use LAN anyways everywhere.
>
> @Chris (from the other mail), I am also using puldeaudio 16.1 on ArchLinux, but sadly it does not
> fix it for me. :( Maybe you can find the bug report?


I found it, and also figured out again, why it was so difficult to find ... it was *not* directly a
pulseaudio bug, but a bug in the libspeexdsp1 library, which also only affected a minority use case
involving e.g. Raspberries (if I understood correctly):

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=799176

I followed the advise of the Debian maintainer at the end of the bug report:

"Version: 1.2.0-1

I believe this bug is fixed with latest unpatched speexdsp upload.

Thanks,
Boyuan Yang"

and installed the latest version of "libspeexdsp1" and I *think* that solved the problem for me.

For reference ... in the debian bug report, they are referring to this commit:
https://gitlab.xiph.org/xiph/speexdsp/-/commit/0e5d424fdba2fd1c132428da38add0c0845b4178

... you will problably have to check when/if this was incorporated into your distribution's version
of the library ... assuming that you ARE hit by the same bug as me ... could as well be something
completely different.


>
> On 19/02/2023 07:46, Sean Greenslade wrote:
>> On Sat, Feb 18, 2023 at 08:44:21PM +0100, NicoHood wrote:
>>> Hey Guys,
>>> I am using pulseaudio for years now, but since Version 14, maybe 15 there is
>>> a crackling in the rtp stream. I've setup RTP just with paprefs, enable the
>>> sender and local receiver on a separate audio device.
>>>
>>> I know that I am reporting this really late and the bug is there for some
>>> years now. I hoped this gets eventually fixed, but it did not. I am using
>>> the latest archlinux pulseaudio.
>>>
>>> Are you guys aware of the issue, does it also happen to you? It is just a
>>> tiny crackling, but you can hear in on good audio boxes. It sound a bit like
>>> the vinyl sound, just not so often. You can hear it on the sender via
>>> loopback and on all other receivers as well.
>>
>> Can you describe your setup in more detail? It's unclear if you're using
>> pulseaudio as the RTP sender, RTP receiver, or both.
>>
>> Occasional audible crackling is usually due to buffer underruns. Are
>> your RTP streams going over a wireless network? If so, have you tried
>> increasing the jitter buffer size on the receiver?
>>
>> --Sean
>>