[alsa-devel] period_time in slave definition
Hi,
According to http://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html , my .asoundrc contains:
pcm.test { type plug slave { pcm "hw:0" format "unchanged" channels "unchanged" rate "unchanged" period_size 1024 buffer_size 4096 } }
While pcm, format, channels, and rate are accepted, the period and buffer fields are refused:
ALSA lib pcm.c:6811:(snd_pcm_slave_conf) Unknown field period_time
I checked the source code and the keywords seem to be ok
pcm.c: static const char *const names[SND_PCM_HW_PARAM_LAST_INTERVAL + 1] = { [SND_PCM_HW_PARAM_FORMAT] = "format", [SND_PCM_HW_PARAM_CHANNELS] = "channels", [SND_PCM_HW_PARAM_RATE] = "rate", [SND_PCM_HW_PARAM_PERIOD_TIME] = "period_time", [SND_PCM_HW_PARAM_PERIOD_SIZE] = "period_size", [SND_PCM_HW_PARAM_BUFFER_TIME] = "buffer_time", [SND_PCM_HW_PARAM_BUFFER_SIZE] = "buffer_size", [SND_PCM_HW_PARAM_PERIODS] = "periods" };
Has any change been introduced recently which is not reflected on wiki yet? Is there a way to specify "default" period and buffer parameters?
Thanks a lot,
Pavel.
On Mon, 28 Feb 2011, Pavel Hofman wrote:
Hi,
According to http://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html , my .asoundrc contains:
pcm.test { type plug slave { pcm "hw:0" format "unchanged" channels "unchanged" rate "unchanged" period_size 1024 buffer_size 4096 } }
While pcm, format, channels, and rate are accepted, the period and buffer fields are refused:
ALSA lib pcm.c:6811:(snd_pcm_slave_conf) Unknown field period_time
It's correct, pcm:plug does not support buffer modifiers. Look to "Automatic conversion plugin".
I checked the source code and the keywords seem to be ok
pcm.c: static const char *const names[SND_PCM_HW_PARAM_LAST_INTERVAL + 1] = { [SND_PCM_HW_PARAM_FORMAT] = "format", [SND_PCM_HW_PARAM_CHANNELS] = "channels", [SND_PCM_HW_PARAM_RATE] = "rate", [SND_PCM_HW_PARAM_PERIOD_TIME] = "period_time", [SND_PCM_HW_PARAM_PERIOD_SIZE] = "period_size", [SND_PCM_HW_PARAM_BUFFER_TIME] = "buffer_time", [SND_PCM_HW_PARAM_BUFFER_SIZE] = "buffer_size", [SND_PCM_HW_PARAM_PERIODS] = "periods" };
It's just a table to translate all possibilites between index and name. The plug plugins allow only this:
err = snd_pcm_slave_conf(root, slave, &sconf, 3, SND_PCM_HW_PARAM_FORMAT, SCONF_UNCHANGED, &sformat, SND_PCM_HW_PARAM_CHANNELS, SCONF_UNCHANGED, &schannels, SND_PCM_HW_PARAM_RATE, SCONF_UNCHANGED, &srate);
Jaroslav
----- Jaroslav Kysela perex@perex.cz Linux Kernel Sound Maintainer ALSA Project, Red Hat, Inc.
Jaroslav Kysela napsal(a):
On Mon, 28 Feb 2011, Pavel Hofman wrote:
Hi,
According to http://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html , my .asoundrc contains:
pcm.test { type plug slave { pcm "hw:0" format "unchanged" channels "unchanged" rate "unchanged" period_size 1024 buffer_size 4096 } }
While pcm, format, channels, and rate are accepted, the period and buffer fields are refused:
ALSA lib pcm.c:6811:(snd_pcm_slave_conf) Unknown field period_time
It's correct, pcm:plug does not support buffer modifiers. Look to "Automatic conversion plugin".
I checked the source code and the keywords seem to be ok
pcm.c: static const char *const names[SND_PCM_HW_PARAM_LAST_INTERVAL + 1] = { [SND_PCM_HW_PARAM_FORMAT] = "format", [SND_PCM_HW_PARAM_CHANNELS] = "channels", [SND_PCM_HW_PARAM_RATE] = "rate", [SND_PCM_HW_PARAM_PERIOD_TIME] = "period_time", [SND_PCM_HW_PARAM_PERIOD_SIZE] = "period_size", [SND_PCM_HW_PARAM_BUFFER_TIME] = "buffer_time", [SND_PCM_HW_PARAM_BUFFER_SIZE] = "buffer_size", [SND_PCM_HW_PARAM_PERIODS] = "periods" };
It's just a table to translate all possibilites between index and name. The plug plugins allow only this:
err = snd_pcm_slave_conf(root, slave, &sconf, 3, SND_PCM_HW_PARAM_FORMAT, SCONF_UNCHANGED, &sformat, SND_PCM_HW_PARAM_CHANNELS, SCONF_UNCHANGED, &schannels, SND_PCM_HW_PARAM_RATE, SCONF_UNCHANGED, &srate); Jaroslav
Thanks a lot for your response. Is there a way to set default period/buffer parameters for applications which do not specify them (i.e. audacious)? My idea was to put it somewhere into device definition in .asoundrc. Dmix is not used.
Thanks,
Pavel.
Jaroslav Kysela napsal(a):
On Mon, 28 Feb 2011, Pavel Hofman wrote:
Hi,
According to http://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html , my .asoundrc contains:
pcm.test { type plug slave { pcm "hw:0" format "unchanged" channels "unchanged" rate "unchanged" period_size 1024 buffer_size 4096 } }
While pcm, format, channels, and rate are accepted, the period and buffer fields are refused:
ALSA lib pcm.c:6811:(snd_pcm_slave_conf) Unknown field period_time
It's correct, pcm:plug does not support buffer modifiers. Look to "Automatic conversion plugin".
I checked the source code and the keywords seem to be ok
pcm.c: static const char *const names[SND_PCM_HW_PARAM_LAST_INTERVAL + 1] = { [SND_PCM_HW_PARAM_FORMAT] = "format", [SND_PCM_HW_PARAM_CHANNELS] = "channels", [SND_PCM_HW_PARAM_RATE] = "rate", [SND_PCM_HW_PARAM_PERIOD_TIME] = "period_time", [SND_PCM_HW_PARAM_PERIOD_SIZE] = "period_size", [SND_PCM_HW_PARAM_BUFFER_TIME] = "buffer_time", [SND_PCM_HW_PARAM_BUFFER_SIZE] = "buffer_size", [SND_PCM_HW_PARAM_PERIODS] = "periods" };
It's just a table to translate all possibilites between index and name. The plug plugins allow only this:
err = snd_pcm_slave_conf(root, slave, &sconf, 3, SND_PCM_HW_PARAM_FORMAT, SCONF_UNCHANGED, &sformat, SND_PCM_HW_PARAM_CHANNELS, SCONF_UNCHANGED, &schannels, SND_PCM_HW_PARAM_RATE, SCONF_UNCHANGED, &srate); Jaroslav
Well, still I do not understand why we are talking about the plug plugin, when I am trying to redefine the slave via pcm_slave. The documentation at http://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html says the pcm_slave can define period_time and buffer_time, while a slightly modified example from the wiki page fails:
pcm_slave.slave_rate44100Hz { pcm "hw:0,0" rate 44100 ---> period_time 1024 }
pcm.rate44100Hz { type plug slave slave_rate44100Hz }
How does the slave definition relate to the plug plugin? Sorry for these basics but I am really trying to understand that, so far no success.
Thanks a lot.
Pavel.
On Tue, 1 Mar 2011, Pavel Hofman wrote:
Jaroslav Kysela napsal(a):
On Mon, 28 Feb 2011, Pavel Hofman wrote:
Hi,
According to http://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html , my .asoundrc contains:
pcm.test { type plug slave { pcm "hw:0" format "unchanged" channels "unchanged" rate "unchanged" period_size 1024 buffer_size 4096 } }
While pcm, format, channels, and rate are accepted, the period and buffer fields are refused:
ALSA lib pcm.c:6811:(snd_pcm_slave_conf) Unknown field period_time
It's correct, pcm:plug does not support buffer modifiers. Look to "Automatic conversion plugin".
I checked the source code and the keywords seem to be ok
pcm.c: static const char *const names[SND_PCM_HW_PARAM_LAST_INTERVAL + 1] = { [SND_PCM_HW_PARAM_FORMAT] = "format", [SND_PCM_HW_PARAM_CHANNELS] = "channels", [SND_PCM_HW_PARAM_RATE] = "rate", [SND_PCM_HW_PARAM_PERIOD_TIME] = "period_time", [SND_PCM_HW_PARAM_PERIOD_SIZE] = "period_size", [SND_PCM_HW_PARAM_BUFFER_TIME] = "buffer_time", [SND_PCM_HW_PARAM_BUFFER_SIZE] = "buffer_size", [SND_PCM_HW_PARAM_PERIODS] = "periods" };
It's just a table to translate all possibilites between index and name. The plug plugins allow only this:
err = snd_pcm_slave_conf(root, slave, &sconf, 3, SND_PCM_HW_PARAM_FORMAT, SCONF_UNCHANGED, &sformat, SND_PCM_HW_PARAM_CHANNELS, SCONF_UNCHANGED, &schannels, SND_PCM_HW_PARAM_RATE, SCONF_UNCHANGED, &srate); JaroslavWell, still I do not understand why we are talking about the plug plugin, when I am trying to redefine the slave via pcm_slave. The documentation at http://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html says the pcm_slave can define period_time and buffer_time, while a slightly modified example from the wiki page fails:
pcm_slave.slave_rate44100Hz { pcm "hw:0,0" rate 44100 ---> period_time 1024 }
pcm.rate44100Hz { type plug slave slave_rate44100Hz }
How does the slave definition relate to the plug plugin? Sorry for these basics but I am really trying to understand that, so far no success.
The above description is an universal description for all slaves. Unfortunately, not all plugins accept the whole range of parameters. You have to look to the snd_pcm_slave_conf() caller which parameters are accepted.
The description should be better.
Jaroslav
----- Jaroslav Kysela perex@perex.cz Linux Kernel Sound Maintainer ALSA Project, Red Hat, Inc.
Jaroslav Kysela napsal(a):
On Tue, 1 Mar 2011, Pavel Hofman wrote:
Jaroslav Kysela napsal(a):
It's correct, pcm:plug does not support buffer modifiers. Look to "Automatic conversion plugin".
I checked the source code and the keywords seem to be ok
pcm.c: static const char *const names[SND_PCM_HW_PARAM_LAST_INTERVAL + 1] = { [SND_PCM_HW_PARAM_FORMAT] = "format", [SND_PCM_HW_PARAM_CHANNELS] = "channels", [SND_PCM_HW_PARAM_RATE] = "rate", [SND_PCM_HW_PARAM_PERIOD_TIME] = "period_time", [SND_PCM_HW_PARAM_PERIOD_SIZE] = "period_size", [SND_PCM_HW_PARAM_BUFFER_TIME] = "buffer_time", [SND_PCM_HW_PARAM_BUFFER_SIZE] = "buffer_size", [SND_PCM_HW_PARAM_PERIODS] = "periods" };
It's just a table to translate all possibilites between index and name. The plug plugins allow only this:
err = snd_pcm_slave_conf(root, slave, &sconf, 3, SND_PCM_HW_PARAM_FORMAT, SCONF_UNCHANGED, &sformat, SND_PCM_HW_PARAM_CHANNELS, SCONF_UNCHANGED, &schannels, SND_PCM_HW_PARAM_RATE, SCONF_UNCHANGED, &srate); JaroslavWell, still I do not understand why we are talking about the plug plugin, when I am trying to redefine the slave via pcm_slave. The documentation at http://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html says the pcm_slave can define period_time and buffer_time, while a slightly modified example from the wiki page fails:
pcm_slave.slave_rate44100Hz { pcm "hw:0,0" rate 44100 ---> period_time 1024 }
pcm.rate44100Hz { type plug slave slave_rate44100Hz }
How does the slave definition relate to the plug plugin? Sorry for these basics but I am really trying to understand that, so far no success.
The above description is an universal description for all slaves. Unfortunately, not all plugins accept the whole range of parameters. You have to look to the snd_pcm_slave_conf() caller which parameters are accepted.
Thanks a lot for your clarification. Would it make sense to add these parameters to the plug plugin? I guess it would not be as simple as in dshare.c:
params.period_size = psize; params.buffer_size = bsize;
when opening the slave.
Or should I use dshare when I need to specify period and buffer parameters outside of the application?
Thanks a lot,
Pavel.
Pavel Hofman napsal(a):
Jaroslav Kysela napsal(a):
On Tue, 1 Mar 2011, Pavel Hofman wrote:
Jaroslav Kysela napsal(a):
It's correct, pcm:plug does not support buffer modifiers. Look to "Automatic conversion plugin".
I checked the source code and the keywords seem to be ok
pcm.c: static const char *const names[SND_PCM_HW_PARAM_LAST_INTERVAL + 1] = { [SND_PCM_HW_PARAM_FORMAT] = "format", [SND_PCM_HW_PARAM_CHANNELS] = "channels", [SND_PCM_HW_PARAM_RATE] = "rate", [SND_PCM_HW_PARAM_PERIOD_TIME] = "period_time", [SND_PCM_HW_PARAM_PERIOD_SIZE] = "period_size", [SND_PCM_HW_PARAM_BUFFER_TIME] = "buffer_time", [SND_PCM_HW_PARAM_BUFFER_SIZE] = "buffer_size", [SND_PCM_HW_PARAM_PERIODS] = "periods" };
It's just a table to translate all possibilites between index and name. The plug plugins allow only this:
err = snd_pcm_slave_conf(root, slave, &sconf, 3, SND_PCM_HW_PARAM_FORMAT, SCONF_UNCHANGED, &sformat, SND_PCM_HW_PARAM_CHANNELS, SCONF_UNCHANGED, &schannels, SND_PCM_HW_PARAM_RATE, SCONF_UNCHANGED, &srate); JaroslavWell, still I do not understand why we are talking about the plug plugin, when I am trying to redefine the slave via pcm_slave. The documentation at http://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html says the pcm_slave can define period_time and buffer_time, while a slightly modified example from the wiki page fails:
pcm_slave.slave_rate44100Hz { pcm "hw:0,0" rate 44100 ---> period_time 1024 }
pcm.rate44100Hz { type plug slave slave_rate44100Hz }
How does the slave definition relate to the plug plugin? Sorry for these basics but I am really trying to understand that, so far no success.
The above description is an universal description for all slaves. Unfortunately, not all plugins accept the whole range of parameters. You have to look to the snd_pcm_slave_conf() caller which parameters are accepted.
Thanks a lot for your clarification. Would it make sense to add these parameters to the plug plugin? I guess it would not be as simple as in dshare.c:
params.period_size = psize; params.buffer_size = bsize;
when opening the slave.
Or should I use dshare when I need to specify period and buffer parameters outside of the application?
Well, dshare resamples to common rate too. That is not the way to go.
Thanks,
Pavel.
Pavel Hofman napsal(a):
Jaroslav Kysela napsal(a):
On Tue, 1 Mar 2011, Pavel Hofman wrote:
Jaroslav Kysela napsal(a):
It's correct, pcm:plug does not support buffer modifiers. Look to "Automatic conversion plugin".
I checked the source code and the keywords seem to be ok
pcm.c: static const char *const names[SND_PCM_HW_PARAM_LAST_INTERVAL + 1] = { [SND_PCM_HW_PARAM_FORMAT] = "format", [SND_PCM_HW_PARAM_CHANNELS] = "channels", [SND_PCM_HW_PARAM_RATE] = "rate", [SND_PCM_HW_PARAM_PERIOD_TIME] = "period_time", [SND_PCM_HW_PARAM_PERIOD_SIZE] = "period_size", [SND_PCM_HW_PARAM_BUFFER_TIME] = "buffer_time", [SND_PCM_HW_PARAM_BUFFER_SIZE] = "buffer_size", [SND_PCM_HW_PARAM_PERIODS] = "periods" };
It's just a table to translate all possibilites between index and name. The plug plugins allow only this:
err = snd_pcm_slave_conf(root, slave, &sconf, 3, SND_PCM_HW_PARAM_FORMAT, SCONF_UNCHANGED, &sformat, SND_PCM_HW_PARAM_CHANNELS, SCONF_UNCHANGED, &schannels, SND_PCM_HW_PARAM_RATE, SCONF_UNCHANGED, &srate); JaroslavWell, still I do not understand why we are talking about the plug plugin, when I am trying to redefine the slave via pcm_slave. The documentation at http://www.alsa-project.org/alsa-doc/alsa-lib/pcm_plugins.html says the pcm_slave can define period_time and buffer_time, while a slightly modified example from the wiki page fails:
pcm_slave.slave_rate44100Hz { pcm "hw:0,0" rate 44100 ---> period_time 1024 }
pcm.rate44100Hz { type plug slave slave_rate44100Hz }
How does the slave definition relate to the plug plugin? Sorry for these basics but I am really trying to understand that, so far no success.
The above description is an universal description for all slaves. Unfortunately, not all plugins accept the whole range of parameters. You have to look to the snd_pcm_slave_conf() caller which parameters are accepted.
Thanks a lot for your clarification. Would it make sense to add these parameters to the plug plugin? I guess it would not be as simple as in dshare.c:
params.period_size = psize; params.buffer_size = bsize;
when opening the slave.
One more question regarding the defaults. Older version of audacious (e.g. in ubuntu karmic) uses a very simple code:
snd_pcm_hw_params_alloca(&hwparams); snd_pcm_hw_params_any(pcm_handle, hwparams); snd_pcm_hw_params_set_access(pcm_handle, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED); snd_pcm_hw_params_set_format(pcm_handle, hwparams, afmt); snd_pcm_hw_params_set_channels(pcm_handle, hwparams, nch); snd_pcm_hw_params_set_rate(pcm_handle, hwparams, rate, 0);
err = snd_pcm_hw_params(pcm_handle, hwparams); if (err < 0) { _ERROR("snd_pcm_hw_params failed: %s", snd_strerror(err)); return -1; }
There is no buffer or period setup. I assume some alsa-lib default value is used. When playing, the period size is set very low:
access: MMAP_INTERLEAVED format: S16_LE subformat: STD channels: 2 rate: 96000 (96000/1) period_size: 8 buffer_size: 8192
As a result, the sound card (ICH5) keeps throwing 12.000 interrupts per second and CPU load is rather high. Does this "default" period_size value make sense? This is the reason I am trying to specify it outside of the application.
Thanks a lot for help.
Pavel.
participants (2)
-
Jaroslav Kysela -
Pavel Hofman