alsa-lib/src/pcm/pcm_ext_parm.h

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/* hw_params */
struct snd_ext_parm {
unsigned int min, max;
unsigned int num_list;
unsigned int *list;
unsigned int active: 1;
unsigned int integer: 1;
pcm: extplug: Keep format and channels the same if requested Without this patch it is not possible to link the channel and format parameter if snd_pcm_extplug_set_param_*() or snd_pcm_extplug_set_slave_param_*() is called. Therefore the client and slave parameter can differ. So the extplug has to implement conversion. To avoid this the new snd_pcm_extplug_set_param_link() function can be called. As a reproduction sceanrio the following extplug source code can be used: === static snd_pcm_sframes_t my_transfer(snd_pcm_extplug_t *e, const snd_pcm_channel_area_t *da, snd_pcm_uframes_t dof, const snd_pcm_channel_area_t *sa, snd_pcm_uframes_t sof, snd_pcm_uframes_t s) { return s; } static const snd_pcm_extplug_callback_t my_own_callback = { .transfer = my_transfer }; SND_PCM_PLUGIN_DEFINE_FUNC(my_plug) { snd_config_iterator_t i, next; snd_config_t *slave = NULL; snd_pcm_extplug_t *myplug; snd_config_for_each(i, next, conf) { snd_config_t *n = snd_config_iterator_entry(i); const char *id; if (snd_config_get_id(n, &id) < 0) continue; if (strcmp(id, "comment") == 0 || strcmp(id, "type") == 0) continue; if (strcmp(id, "slave") == 0) { slave = n; continue; } return -EINVAL; } myplug = calloc(1, sizeof(*myplug)); myplug->version = SND_PCM_EXTPLUG_VERSION; myplug->callback = &my_own_callback; snd_pcm_extplug_create(myplug, name, root, slave, stream, mode); snd_pcm_extplug_set_param_minmax(myplug, SND_PCM_EXTPLUG_HW_CHANNELS, 1, 16); // snd_pcm_extplug_set_param_link(myplug, SND_PCM_EXTPLUG_HW_CHANNELS, 1); *pcmp = myplug->pcm; return 0; } SND_PCM_PLUGIN_SYMBOL(my_plug); === To use this plugin the following ALSA configuration is required: pcm.myplug { type my_plug slave.pcm hw:Dummy } With this configuration without this patch snd_pcm_hw_params_get_channels_max() will always return 16 channels independent of the supported channels of the dummy device. Due to that for example the start up of JACK would fail: $ modprobe snd_dummy $ jackd -d alsa -P myplug ALSA: cannot set channel count to 16 for playback ALSA: cannot configure playback channel Signed-off-by: Timo Wischer <twischer@de.adit-jv.com> Signed-off-by: Takashi Iwai <tiwai@suse.de>
2018-12-10 11:33:16 +01:00
unsigned int keep_link: 1;
};
static inline snd_mask_t *hw_param_mask(snd_pcm_hw_params_t *params,
snd_pcm_hw_param_t var)
{
return &params->masks[var - SND_PCM_HW_PARAM_FIRST_MASK];
}
static inline snd_interval_t *hw_param_interval(snd_pcm_hw_params_t *params,
snd_pcm_hw_param_t var)
{
return &params->intervals[var - SND_PCM_HW_PARAM_FIRST_INTERVAL];
}
/* make local functions really local */
#define snd_ext_parm_set_minmax \
snd1_ext_parm_set_minmax
#define snd_ext_parm_set_list \
snd1_ext_parm_set_list
#define snd_ext_parm_clear \
snd1_ext_parm_clear
#define snd_interval_list \
snd1_interval_list
#define snd_ext_parm_interval_refine \
snd1_ext_parm_interval_refine
#define snd_ext_parm_mask_refine \
snd1_ext_parm_mask_refine
int snd_ext_parm_set_minmax(struct snd_ext_parm *parm, unsigned int min, unsigned int max);
int snd_ext_parm_set_list(struct snd_ext_parm *parm, unsigned int num_list, const unsigned int *list);
void snd_ext_parm_clear(struct snd_ext_parm *parm);
int snd_interval_list(snd_interval_t *ival, int num_list, unsigned int *list);
int snd_ext_parm_interval_refine(snd_interval_t *ival, struct snd_ext_parm *parm, int type);
int snd_ext_parm_mask_refine(snd_mask_t *mask, struct snd_ext_parm *parm, int type);