[alsa-devel] Meaning of this Plug PCM Transformation table?

[Nobin Mathew]

Plug PCM: Route conversion PCM (sformat=S16_LE)
  Transformation table:
    0 <- 0
    1 <- 0
Its setup is:
  stream       : PLAYBACK
  access       : MMAP_INTERLEAVED
  format       : S16_LE
  subformat    : STD
  channels     : 1
  rate         : 8000
  exact rate   : 8000 (8000/1)
  msbits       : 16
  buffer_size  : 4000
  period_size  : 256
  period_time  : 32000
  tick_time    : 10000
  tstamp_mode  : NONE
  period_step  : 1
  sleep_min    : 0
  avail_min    : 256
  xfer_align   : 256
  start_threshold  : 3840
  stop_threshold   : 4000
  silence_threshold: 0
  silence_size : 0
  boundary     : 2097152000
Slave: Hardware PCM card 0 'IDENTITY' device 0 subdevice 0
Its setup is:
  stream       : PLAYBACK
  access       : MMAP_INTERLEAVED
  format       : S16_LE
  subformat    : STD
  channels     : 2
  rate         : 8000
  exact rate   : 8000 (8000/1)
  msbits       : 16
  buffer_size  : 4000
  period_size  : 256
  period_time  : 32000
  tick_time    : 10000
  tstamp_mode  : NONE
  period_step  : 1
  sleep_min    : 0
  avail_min    : 256
  xfer_align   : 256
  start_threshold  : 3840
  stop_threshold   : 4000
  silence_threshold: 0
  silence_size : 0
  boundary     : 2097152000



This is capture Handle logs

Plug PCM: Route conversion PCM (sformat=S16_LE)
  Transformation table:
    0 <- 0*0.5 + 1*0.5
Its setup is:
  stream       : CAPTURE
  access       : MMAP_INTERLEAVED
  format       : S16_LE
  subformat    : STD
  channels     : 1
  rate         : 8000
  exact rate   : 8000 (8000/1)
  msbits       : 16
  buffer_size  : 4000
  period_size  : 256
  period_time  : 32000
  tick_time    : 10000
  tstamp_mode  : NONE
  period_step  : 1
  sleep_min    : 0
  avail_min    : 256
  xfer_align   : 256
  start_threshold  : 1
  stop_threshold   : 4000
  silence_threshold: 0
  silence_size : 0
  boundary     : 2097152000
Slave: Hardware PCM card 0 'IDENTITY' device 0 subdevice 0
Its setup is:
  stream       : CAPTURE
  access       : MMAP_INTERLEAVED
  format       : S16_LE
  subformat    : STD
  channels     : 2
  rate         : 8000
  exact rate   : 8000 (8000/1)
  msbits       : 16
  buffer_size  : 4000
  period_size  : 256
  period_time  : 32000
  tick_time    : 10000
  tstamp_mode  : NONE
  period_step  : 1
  sleep_min    : 0
  avail_min    : 256
  xfer_align   : 256
  start_threshold  : 1
  stop_threshold   : 4000
  silence_threshold: 0
  silence_size : 0
  boundary     : 2097152000


I am having an application which does capture and playback
simultaneously and is single threaded?

What is the meaning of this Transformation table?