Re: [LAD] Writing a driver for a device which clears the buffer on the start trigger

[Adrian Knoth]

On Wed, Jul 31, 2019 at 09:34:45PM +0200, Paul Pawlowski wrote:

> Hello,

Hi!

> I have got the driver working to some extent by moving the Start IO command
> code to the open() callback instead of the trigger(SNDRV_PCM_TRIGGER_START)
> however that's obviously a hack and causes issues (the first ~0.1s of audio
> is lost).

You're probably better off on alsa-devel@:

   https://alsa-project.org/wiki/Mailing-lists#alsa-devel_at_alsa-project.org


I have no good immediate solution to offer (I lost touch with Linux
audio 5yrs ago, don't know why I'm still on this list :) ). Maybe you
can even start streaming in the chip init function and track in a
bool whether this is the actual stream or not. If not, then send
silence (memset the buffer, so that there's no noise), and only send
real data if there was a start command.

Terrible hack and obviously bad for power consumption.

I'm sure Takashi has better ideas on alsa-devel@. ;)

-- 
mail: a...@thur.de  http://adi.thur.de  PGP/GPG: key via keyserver
___
Linux-audio-dev mailing list
Linux-audio-dev@lists.linuxaudio.org
https://lists.linuxaudio.org/listinfo/linux-audio-dev

Re: [LAD] jack meterbridge 0.9.2 update / maintenance

[Jörn Nettingsmeier]

On 7/29/19 8:44 PM, Robin Gareus wrote:

On 7/29/19 8:21 PM, Stephan Bourgeois wrote:


Should meterbridge be maintained or should another metering app de bundled
with jack?


Given that jack is cross-platform and meterbridge is a X11 application
it's not very likely to be bundled with jack itself.

The main use-case for meterbridge is the dpm mode with many channels to
check input activity.

You may also want to have a look at
https://lists.linuxaudio.org/archives/linux-audio-dev/2012-June/032475.html
- the debian package applied this, but it never reached upstream, it's
likely not relevant after your re-work either.


A better candidate to be bundled with JACK would be 
https://github.com/njh/jackmeter (although I tend to prefer jack_capture 
/dev/null, b/c it does multiple channels). A simple command line meter 
for troubleshooting would be great. But ballistics are of secondary 
importance, this is more to check if it's alive. That also means it 
should go down to -100dB or so.


That said, a "signal present" indicator would help in all patchbay 
applications such as patchage and qjackctl (switchable of course to not 
waste resources when not needed).



--
Jörn Nettingsmeier
Tuinbouwstraat 180, 1097 ZB Amsterdam, Nederland
Tel. +49 177 7937487

Meister für Veranstaltungstechnik (Bühne/Studio), Tonmeister VDT
http://stackingdwarves.net
___
Linux-audio-dev mailing list
Linux-audio-dev@lists.linuxaudio.org
https://lists.linuxaudio.org/listinfo/linux-audio-dev