[pulseaudio-discuss] [RFC] (alsa-lib)pcm_hw.c: SNDRV_PCM_IOCTL_START failed (-77) proposed fix to check pcm state

[Takashi Iwai]

At Thu, 27 Nov 2014 14:42:00 +0800,
Raymond Yau wrote:
> 
> > >
> > > For those creative sound cards (e.g. emu10k1, ca0106) which use multi
> > > plugin for surround playback
> > >
> > > It seem that set start_threshold to -1 has no effect on some devices
> (e.g.
> > > multi plugin) , the device seem  automatically started and pulseaudio
> does
> > > not check pcm state when calling snd_pcm_start
> > >
> > > (alsa-lib)pcm_hw.c: SNDRV_PCM_IOCTL_START failed (-77)
> > >
> > > Does it mean bug of multi plugin or start_threshold.have no effect on
> some
> > > devices/plugin ?
> >
> > I'm not sure whether the value -1 is valid for start_threshold at
> > all.  Usually it's set between 1 and boundary.
> >
> >
> If zero is not valid stop threshold, I suggest to return error when
> application set start threshold to zero

If the expected behavior is not to start stream automatically, try to
change -1 with the value obtained from
snd_pcm_sw_params_get_boundary() (after calling
snd_pcm_sw_params_current()).  Does it work better?


Takashi