[pulseaudio-discuss] Raspberry Pi Model B+ has Improved Audio

Michael DePaulo mikedep333 at gmail.com
Mon Jul 14 05:21:40 PDT 2014


I've seen many people post about the Raspberry Pi over the last year.
So I thought I'd point this out:


>From a thread about the old models:
Re: [pulseaudio-discuss] pulseaudio settop boxes
On Sat, Feb 8, 2014 at 5:21 PM, Laurențiu Nicola <lnicola at dend.ro> wrote:
> Hi Wolfgang,
> First of all, I hope I won't offend anyone with this email, as it's not
> really related to PulseAudio and I should probably have taken it
> off-list.
> The complaints are usually related to the integrated sound card, which
> uses PWM (although at a rather high frequency). I tried to use it only
> once and, while I can't really comment on the audio quality, it seemed
> to have a lot of interference: when the Pi was writing to the SD card,
> there was a lot of audible noise. I'm using an USB DAC (sound card).
> Initially I was using ALSA, but the audio was choppy until I changed the
> sampling rate to 44100 Hz. The USB support is not great on the Raspberry
> Pi and there was a series of kernel changes intended to fix some
> problems with keyboards or something like this. I'm running mine
> headless, and those changes caused audio distortion for me, but luckily
> they can be disabled from configuration. The Raspberry Pi also has I2S
> support, which is a dedicated audio bus, supporting high sampling rates
> and bit depths. There are some I2S sound cards available and the drivers
> were recently merged into the kernel.
> Another series of problems was SD card corruption for me, as the Pi
> would not boot anymore if I restarted it improperly (which happens quite
> often because the power connector on mine is a bit finicky), but this
> seems to happen less often with newer firmwares.
> As for PulseAudio, I'm using the RTP module with an application I wrote.
> The CPU usage is rather high, but this is probably due to the resampler
> (which is needed for RTP because of the clock skew). The rate estimation
> algorithm seems to be a bit buggy: sometimes the buffer size grows too
> much, at other times the audio gets choppy (although I find it weird
> that I have to restart PA, not just the RTP session to fix it) and
> sometimes it stops playing at all. However, I expect that these are
> issues with the RTP module, not with the rest of PulseAudio.
> Basically, you can make it work and it's not that much of a hassle.
> Regards,
> Laurentiu
> On Sat, Feb 8, 2014, at 23:00, hamann.w at t-online.de wrote:
>> >> Hello,
>> >>
>> >> I'm not sure this is what you expect to get as an answer, but I'm using
>> >> PulseAudio on a Raspberry Pi. It "mostly" works.
>> >>
>> >> Laurentiu
>> >>
>> Hi Laurentiu,
>> I thought about something along these lines ... but I recall that people
>> are complaining
>> about the audio quality. Are you using the analog output? And what kind
>> of
>> obstacles does the "mostly" refer to?
>> Regards
>> Wolfgang
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