[alsa-devel] [PATCH 2/2] Improve hw_params documentation
Raymond Yau
superquad.vortex2 at gmail.com
Mon Nov 21 23:31:03 CET 2011
2011/11/17 Andrew Eikum <aeikum at codeweavers.com>:
> On Wed, Nov 16, 2011 at 11:08:37PM +0100, Clemens Ladisch wrote:
>> On 11/16/2011 10:31 PM, Andrew Eikum wrote:
>> > On Wed, Nov 16, 2011 at 10:20:07PM +0100, Clemens Ladisch wrote:
>> >> Andrew Eikum wrote:
>> >>> +++ b/include/pcm.h
>> >>> @@ -44,8 +44,20 @@ extern "C" {
>> >>>
>> >>> /** PCM generic info container */
>> >>> typedef struct _snd_pcm_info snd_pcm_info_t;
>> >>> -/** PCM hardware configuration space container */
>> >>> +
>> >>> +/** PCM hardware configuration space container
>> >>> + *
>> >>> + * snd_pcm_hw_params_t is an opaque structure which contains a set of possible
>> >>> + * PCM hardware configurations. For example, a given instance might include a
>> >>> + * range of buffer sizes, a range of period sizes, and a set of several sample
>> >>> + * formats. Some subset of all possible combinations these sets may be valid,
>> >>> + * but not necessarily any combination will be valid.
>> >>> + *
>> >>> + * No validation is done by the various snd_pcm_hw_params_set* functions.
>> >>
>> >> These functions do validate the value that the application is trying to set
>> >> and adjust all other dependent limits.
>> >
>> > I didn't find that to be the case in my testing, at least between
>> > periods, period_size, and buffer_size. I've attached a test program
>> > here.
>>
>> I can reproduce this.
>>
>> Try running the program with LIBASOUND_DEBUG=1; it appears that there is
>> a bug in the rate plugin. (Normal programs actually set their rate ...)
>
> This doesn't change the output in any way. I checked the Arch Linux
> alsa-lib build script[1] and it doesn't seem to disable debugging in
> any obvious way. Do I have to explicitly enable debugging output and
> rebuild?
>
> $ LIBASOUND_DEBUG=1 ./alsa_period_count
> min_buffer_frames: 80
> set max buffer size: 80
> snd_pcm_hw_params: -12
> $
>
> [1] http://projects.archlinux.org/svntogit/packages.git/tree/trunk/PKGBUILD?h=packages/alsa-lib
>
There is a bug in your program which set the buffer_size_max to buffer_size_min
err = snd_pcm_hw_params_set_periods(pcm, hw_params, 10, 0);
if(err < 0){
printf("snd_pcm_hw_params_set_periods: %d\n", err);
return 1;
}
err = snd_pcm_hw_params_set_period_size(pcm, hw_params, 1024, 0);
if(err < 0){
printf("snd_pcm_hw_params_set_period_size: %d\n", err);
return 1;
}
The above already set buffer size to 10240, but you set
buffer_size_max to buffer_size_min (80)
err = snd_pcm_hw_params_get_buffer_size_min(hw_params, &buffer_frames);
if(err < 0){
printf("snd_pcm_hw_params_get_buffer_size: %d\n", err);
return 1;
}
printf("min_buffer_frames: %u\n", buffer_frames);
err = snd_pcm_hw_params_set_buffer_size_max(pcm, hw_params, &buffer_frames);
if(err < 0){
printf("snd_pcm_hw_params_get_buffer_size: %d\n", err);
return 1;
}
printf("set max buffer size: %u\n", buffer_frames);
./alsa_period_count pulse
refine_soft 'pulse' (begin)
ACCESS: RW_INTERLEAVED
FORMAT: U8 S16_LE S16_BE S32_LE S32_BE FLOAT_LE FLOAT_BE MU_LAW A_LAW
SUBFORMAT: ALL
SAMPLE_BITS: ALL
FRAME_BITS: ALL
CHANNELS: [1 32]
RATE: [1 192000]
PERIOD_TIME: ALL
PERIOD_SIZE: ALL
PERIOD_BYTES: ALL
PERIODS: ALL
BUFFER_TIME: ALL
BUFFER_SIZE: ALL
BUFFER_BYTES: ALL
TICK_TIME: ALL
Rule 0 (0x160f80): FORMAT= U8 S16_LE S16_BE S32_LE S32_BE FLOAT_LE
FLOAT_BE MU_LAW A_LAW -> U8 S16_LE S16_BE S32_LE S32_BE FLOAT_LE
FLOAT_BE MU_LAW A_LAW SAMPLE_BITS=[1 4294967295]
Rule 1 (0x160e70): SAMPLE_BITS=[1 4294967295] -> [8 32] FORMAT= U8
S16_LE S16_BE S32_LE S32_BE FLOAT_LE FLOAT_BE MU_LAW A_LAW
SAMPLE_BITS=[8 32]
Rule 2 (0x160df0): SAMPLE_BITS=[8 32] -> [8 32] FRAME_BITS=[1
4294967295] CHANNELS=[1 32]
Rule 3 (0x160d70): FRAME_BITS=[1 4294967295] -> [8 1024]
SAMPLE_BITS=[8 32] CHANNELS=[1 32]
Rule 4 (0x160cf0): FRAME_BITS=[8 1024] -> [8 1024] PERIOD_BYTES=ALL
PERIOD_SIZE=ALL
Rule 5 (0x160cf0): FRAME_BITS=[8 1024] -> [8 1024] BUFFER_BYTES=[1
4294967295] BUFFER_SIZE=[1 4294967295]
Rule 6 (0x160df0): CHANNELS=[1 32] -> [1 32] FRAME_BITS=[8 1024]
SAMPLE_BITS=[8 32]
Rule 7 (0x160cf0): RATE=[1 192000] -> [1 192000] PERIOD_SIZE=ALL PERIOD_TIME=ALL
Rule 8 (0x160cf0): RATE=[1 192000] -> [1 192000] BUFFER_SIZE=[1
4294967295] BUFFER_TIME=[1 4294967295]
Rule 9 (0x160df0): PERIODS=ALL -> (0 4294967295] BUFFER_SIZE=[1
4294967295] PERIOD_SIZE=ALL
Rule 10 (0x160df0): PERIOD_SIZE=ALL -> (0 4294967295] BUFFER_SIZE=[1
4294967295] PERIODS=(0 4294967295]
Rule 11 (0x160cf0): PERIOD_SIZE=(0 4294967295] -> (0 4294967295]
PERIOD_BYTES=ALL FRAME_BITS=[8 1024]
Rule 12 (0x160c70): PERIOD_SIZE=(0 4294967295] -> (0 824633721)
PERIOD_TIME=ALL RATE=[1 192000]
Rule 13 (0x160d70): BUFFER_SIZE=[1 4294967295] -> [1 4294967294]
PERIOD_SIZE=(0 824633721) PERIODS=(0 4294967295]
Rule 14 (0x160cf0): BUFFER_SIZE=[1 4294967294] -> [1 4294967294]
BUFFER_BYTES=[1 4294967295] FRAME_BITS=[8 1024]
Rule 15 (0x160c70): BUFFER_SIZE=[1 4294967294] -> [1 824633720]
BUFFER_TIME=[1 4294967295] RATE=[1 192000]
Rule 16 (0x160c70): PERIOD_BYTES=ALL -> (0 4294967295) PERIOD_SIZE=(0
824633721) FRAME_BITS=[8 1024]
Rule 17 (0x160c70): BUFFER_BYTES=[1 4294967295] -> [1 4294967295]
BUFFER_SIZE=[1 824633720] FRAME_BITS=[8 1024]
Rule 18 (0x160cf0): PERIOD_TIME=ALL -> (0 4294967295) PERIOD_SIZE=(0
824633721) RATE=[1 192000]
Rule 19 (0x160cf0): BUFFER_TIME=[1 4294967295] -> (5 4294967295]
BUFFER_SIZE=[1 824633720] RATE=[1 192000]
Rule 0 (0x160f80): FORMAT= U8 S16_LE S16_BE S32_LE S32_BE FLOAT_LE
FLOAT_BE MU_LAW A_LAW -> U8 S16_LE S16_BE S32_LE S32_BE FLOAT_LE
FLOAT_BE MU_LAW A_LAW SAMPLE_BITS=[8 32]
Rule 2 (0x160df0): SAMPLE_BITS=[8 32] -> [8 32] FRAME_BITS=[8 1024]
CHANNELS=[1 32]
Rule 4 (0x160cf0): FRAME_BITS=[8 1024] -> [8 1024] PERIOD_BYTES=(0
4294967295) PERIOD_SIZE=(0 824633721)
Rule 5 (0x160cf0): FRAME_BITS=[8 1024] -> [8 1024] BUFFER_BYTES=[1
4294967295] BUFFER_SIZE=[1 824633720]
Rule 7 (0x160cf0): RATE=[1 192000] -> [1 192000] PERIOD_SIZE=(0
824633721) PERIOD_TIME=(0 4294967295)
Rule 8 (0x160cf0): RATE=[1 192000] -> [1 192000] BUFFER_SIZE=[1
824633720] BUFFER_TIME=(5 4294967295]
Rule 9 (0x160df0): PERIODS=(0 4294967295] -> (0 4294967295]
BUFFER_SIZE=[1 824633720] PERIOD_SIZE=(0 824633721)
Rule 10 (0x160df0): PERIOD_SIZE=(0 824633721) -> (0 824633721)
BUFFER_SIZE=[1 824633720] PERIODS=(0 4294967295]
Rule 11 (0x160cf0): PERIOD_SIZE=(0 824633721) -> (0 824633721)
PERIOD_BYTES=(0 4294967295) FRAME_BITS=[8 1024]
Rule 12 (0x160c70): PERIOD_SIZE=(0 824633721) -> (0 824633721)
PERIOD_TIME=(0 4294967295) RATE=[1 192000]
Rule 15 (0x160c70): BUFFER_SIZE=[1 824633720] -> [1 824633720]
BUFFER_TIME=(5 4294967295] RATE=[1 192000]
min periods 3
max periods 1024
min_buffer_frames: 80
set max buffer size: 80
refine_soft 'pulse' (begin)
ACCESS: RW_INTERLEAVED
FORMAT: U8
SUBFORMAT: STD
SAMPLE_BITS: [8 32]
FRAME_BITS: [8 1024]
CHANNELS: [1 32]
RATE: [1 192000]
PERIOD_TIME: (5333 1024000000]
PERIOD_SIZE: 1024
PERIOD_BYTES: 1024
PERIODS: 10
BUFFER_TIME: (416 80000000]
BUFFER_SIZE: 80
BUFFER_BYTES: 10240
TICK_TIME: ALL
Rule 1 (0x160e70): SAMPLE_BITS=[8 32] -> 8 FORMAT= U8 SAMPLE_BITS=8
Rule 3 (0x160d70): FRAME_BITS=[8 1024] -> [8 256] SAMPLE_BITS=8 CHANNELS=[1 32]
Rule 4 (0x160cf0): FRAME_BITS=[8 256] -> 8 PERIOD_BYTES=1024 PERIOD_SIZE=1024
Rule 5 (0x160cf0): FRAME_BITS=8 -> NONE BUFFER_BYTES=10240 BUFFER_SIZE=80
refine_soft 'pulse' (end--22)
ACCESS: RW_INTERLEAVED
FORMAT: U8
SUBFORMAT: STD
SAMPLE_BITS: 8
FRAME_BITS: NONE
CHANNELS: [1 32]
RATE: [1 192000]
PERIOD_TIME: (5333 1024000000]
PERIOD_SIZE: 1024
PERIOD_BYTES: 1024
PERIODS: 10
BUFFER_TIME: (416 80000000]
BUFFER_SIZE: 80
BUFFER_BYTES: 10240
TICK_TIME: ALL
snd_pcm_hw_params: -12
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