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Create rate converter plugin SDK

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Created a new rate converter plugin SDK.
A rate converter can be replaced as an extra plugin now.
The default rate converter is a built-in linear converter.

You can find a sample external converter in alsa-plugins package.
This commit is contained in:
Takashi Iwai 2006-04-06 18:37:55 +02:00
parent 8f605df24a
commit 33d69ef33b
8 changed files with 879 additions and 461 deletions
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28
src/pcm/pcm_plug.c
View file

@ -50,6 +50,7 @@ typedef struct {
snd_pcm_format_t sformat;
int schannels;
int srate;
const char *rate_converter;
enum snd_pcm_plug_route_policy route_policy;
snd_pcm_route_ttable_entry_t *ttable;
int ttable_ok, ttable_last;
@ -359,7 +360,8 @@ static int snd_pcm_plug_change_rate(snd_pcm_t *pcm, snd_pcm_t **new, snd_pcm_plu
if (clt->rate == slv->rate)
return 0;
assert(snd_pcm_format_linear(slv->format));
err = snd_pcm_rate_open(new, NULL, slv->format, slv->rate, plug->gen.slave, plug->gen.slave != plug->req_slave);
err = snd_pcm_rate_open(new, NULL, slv->format, slv->rate, plug->rate_converter,
plug->gen.slave, plug->gen.slave != plug->req_slave);
if (err < 0)
return err;
slv->access = clt->access;
@ -1013,6 +1015,7 @@ static snd_pcm_ops_t snd_pcm_plug_ops = {
int snd_pcm_plug_open(snd_pcm_t **pcmp,
const char *name,
snd_pcm_format_t sformat, int schannels, int srate,
const char *rate_converter,
enum snd_pcm_plug_route_policy route_policy,
snd_pcm_route_ttable_entry_t *ttable,
unsigned int tt_ssize,
@ -1030,6 +1033,7 @@ int snd_pcm_plug_open(snd_pcm_t **pcmp,
plug->sformat = sformat;
plug->schannels = schannels;
plug->srate = srate;
plug->rate_converter = rate_converter;
plug->gen.slave = plug->req_slave = slave;
plug->gen.close_slave = close_slave;
plug->route_policy = route_policy;
@ -1087,6 +1091,8 @@ pcm.name {
SCHANNEL REAL # route value (0.0 - 1.0)
}
}
rate_converter STR # type of rate converter
# default value is taken from defaults.pcm.rate_converter
}
\endcode
@ -1127,6 +1133,8 @@ int _snd_pcm_plug_open(snd_pcm_t **pcmp, const char *name,
unsigned int cused, sused;
snd_pcm_format_t sformat = SND_PCM_FORMAT_UNKNOWN;
int schannels = -1, srate = -1;
const char *rate_converter = NULL;
snd_config_for_each(i, next, conf) {
snd_config_t *n = snd_config_iterator_entry(i);
const char *id;
@ -1166,6 +1174,17 @@ int _snd_pcm_plug_open(snd_pcm_t **pcmp, const char *name,
route_policy = PLUG_ROUTE_POLICY_DUP;
continue;
}
#endif
#ifdef BUILD_PCM_PLUGIN_RATE
if (strcmp(id, "rate_converter") == 0) {
const char *str;
if ((err = snd_config_get_string(n, &str)) < 0) {
SNDERR("Invalid type for %s", id);
return -EINVAL;
}
rate_converter = str;
continue;
}
#endif
SNDERR("Unknown field %s", id);
return -EINVAL;
@ -1200,11 +1219,16 @@ int _snd_pcm_plug_open(snd_pcm_t **pcmp, const char *name,
}
#endif
#ifdef BUILD_PCM_PLUGIN_RATE
if (! rate_converter)
rate_converter = snd_pcm_rate_get_default_converter(root);
#endif
err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf);
snd_config_delete(sconf);
if (err < 0)
return err;
err = snd_pcm_plug_open(pcmp, name, sformat, schannels, srate,
err = snd_pcm_plug_open(pcmp, name, sformat, schannels, srate, rate_converter,
route_policy, ttable, ssize, cused, sused, spcm, 1);
if (err < 0)
snd_pcm_close(spcm);