[alsa-devel] plug:dmix slows playback

[Steve Langstaff]

> From: alsa-devel-bounces at alsa-project.org [mailto:alsa-devel-
> bounces at alsa-project.org] On Behalf Of Jaroslav Kysela

> On Fri, 12 Jun 2009, Steve Langstaff wrote:
> 
> > Hi All.
> >
> > I've got an installation of ALSA (1.0.19 on an embedded device) where
> using
> > plug and dmix as my output device slows down playback - voices and
> tones are
> > lower in pitch and the playback takes longer than when not using
> plug:dmix,
> > e.g.
> 
> Does 48000Hz 2 channel source work OK with direct device (without dmix)
> for your hardware?

Yes, I converted the original sample to 48000 Hz, Stereo, and it sounds OK
when I don't use dmix.

/mnt # time aplay -v ignition48000s.wav
Playing WAVE 'ignition48000s.wav' : Unsigned 8 bit, Rate 48000 Hz, Stereo
Plug PCM: Linear conversion PCM (S16_LE)
Its setup is:
  stream       : PLAYBACK
  access       : RW_INTERLEAVED
  format       : U8
  subformat    : STD
  channels     : 2
  rate         : 48000
  exact rate   : 48000 (48000/1)
  msbits       : 8
  buffer_size  : 24480
  period_size  : 2040
  period_time  : 42500
  tstamp_mode  : NONE
  period_step  : 1
  avail_min    : 2040
  period_event : 0
  start_threshold  : 24480
  stop_threshold   : 24480
  silence_threshold: 0
  silence_size : 0
  boundary     : 1604321280
Slave: Hardware PCM card 0 'LM4549' device 0 subdevice 0
Its setup is:
  stream       : PLAYBACK
  access       : MMAP_INTERLEAVED
  format       : S16_LE
  subformat    : STD
  channels     : 2
  rate         : 48000
  exact rate   : 48000 (48000/1)
  msbits       : 16
  buffer_size  : 24480
  period_size  : 2040
  period_time  : 42500
  tstamp_mode  : NONE
  period_step  : 1
  avail_min    : 2040
  period_event : 0
  start_threshold  : 24480
  stop_threshold   : 24480
  silence_threshold: 0
  silence_size : 0
  boundary     : 1604321280
  appl_ptr     : 0
  hw_ptr       : 0
real    0m 3.02s
user    0m 0.07s
sys     0m 0.02s