[alsa-devel] [PATCH 2/2 v2] Improve hw_params documentation

[Raymond Yau]

2011/11/23 Andrew Eikum <aeikum at codeweavers.com>:
> ---
>
> Tweaked the snd_pcm_hw_params_t description to reflect how ALSA is
> intended to work, even if that's not how some plugins (pulse)
> currently work due to bugs.
>
>  include/pcm.h |   17 ++++++++++++++++-
>  src/pcm/pcm.c |   10 +++++++++-
>  2 files changed, 25 insertions(+), 2 deletions(-)
>
>

But Tick time is already deprecated.

Some sound cards such au88x0 may return error when there is no enough SRC


and there is another error for plughw with snd-hda-intel


./alsa_period_count plughw:1
min periods 0  dir 1
max periods 4294967295 dir 0
min_buffer_frames: 10240
set max buffer size: 10240
snd_pcm_hw_params: -22
[raymond at localhost ~]$ export LIBASOUND_DEBUG=1
[raymond at localhost ~]$ ./alsa_period_count plughw:1
min periods 0  dir 1
max periods 4294967295 dir 0
min_buffer_frames: 10240
set max buffer size: 10240
ALSA ERROR hw_params: set (RATE)
           value = 4000 : Invalid argument
ACCESS:  MMAP_INTERLEAVED RW_INTERLEAVED
FORMAT:  S16_LE S32_LE
SUBFORMAT:  STD
SAMPLE_BITS: [16 32]
FRAME_BITS: [32 448]
CHANNELS: [2 14]
RATE: [8000 192000]
PERIOD_TIME: (15 1024000]
PERIOD_SIZE: [3 8192]
PERIOD_BYTES: [128 458752]
PERIODS: [2 32]
BUFFER_TIME: (31 2048000]
BUFFER_SIZE: [6 16384]
BUFFER_BYTES: [128 65536]
TICK_TIME: ALL
ALSA ERROR hw_params: set (RATE)
           value = 4000 : Invalid argument
ACCESS:  MMAP_INTERLEAVED RW_INTERLEAVED
FORMAT:  S16_LE S32_LE
SUBFORMAT:  STD
SAMPLE_BITS: [16 32]
FRAME_BITS: [32 448]
CHANNELS: [2 14]
RATE: [8000 192000]
PERIOD_TIME: (15 1024000]
PERIOD_SIZE: [3 8192]
PERIOD_BYTES: [128 458752]
PERIODS: [2 32]
BUFFER_TIME: (31 2048000]
BUFFER_SIZE: [6 16384]
BUFFER_BYTES: [128 65536]
TICK_TIME: ALL
snd_pcm_hw_params: -22