* loopback snd_pcm_writei
@ 2019-04-01 13:51 Giuliano Zannetti - ART S.p.A.
2019-04-09 8:36 ` Jaroslav Kysela
0 siblings, 1 reply; 3+ messages in thread
From: Giuliano Zannetti - ART S.p.A. @ 2019-04-01 13:51 UTC (permalink / raw
To: alsa-devel@alsa-project.org
Hi,
I have the configuration in the asound.conf above.
my_plug - - > my_route - - > my_multi - - > slave0 (forward)
- - > slave1 (loopback)
I open the plug my_plug in the block mode:
writtenFrames = snd_pcm_writei(handle, bufferToWrite, bufferToWriteSize);
The issue I see is that there are several "writes" with 0 written frames. It seems like the snd_pcm_writei does not hold until data will be written. In general, 0 written frames sounds weird to me, because snd_pcm_writei should block itself if no space is available in the circular buffer right?
I have tried to fix the following method in pcm_multi.c, as Jaroslav Kysela suggests.
-static int snd_pcm_multi_may_wait_for_avail_min(snd_pcm_t *pcm, snd_pcm_uframes_t avail ATTRIBUTE_UNUSED)
+static int snd_pcm_multi_may_wait_for_avail_min(snd_pcm_t *pcm, snd_pcm_uframes_t avail)
{
snd_pcm_multi_t *multi = pcm->private_data;
- snd_pcm_t *slave = multi->slaves[multi->master_slave].pcm;
- return snd_pcm_may_wait_for_avail_min(slave, snd_pcm_mmap_avail(slave));
+ unsigned int i;
+ for (i = 0; i < multi->slaves_count; ++i) {
+ if (snd_pcm_may_wait_for_avail_min(multi->slaves[i].pcm, avail))
+ return 1;
+ }
+ return 0;
}
But unfortunately the issue has not been resolved.
#*************************************************
# PLAYBACK
#*************************************************
pcm.my_plug
{
type plug
slave.pcm my_route
slave.channels 2
}
pcm.my_route
{
type route
slave.pcm my_multi
slave.channels 4
ttable.0.0 1
ttable.0.1 1
ttable.1.2 1
ttable.1.3 1
}
pcm.my_multi
{
type multi
slaves
{
slave0
{
pcm my_dmix
channels 2
}
slave1
{
pcm my_dmix_loop
channels 2
}
}
bindings
{
0 {slave slave0 channel 0}
1 {slave slave0 channel 1}
2 {slave slave1 channel 0}
3 {slave slave1 channel 1}
}
}
#-------------------- Slave 0 --------------------
pcm.my_dmix
{
type dmix
ipc_key 1000
ipc_key_add_uid 1
ipc_perm 0600
slave.period_time 10000
slave.period_size 480
slave.buffer_size 3840
slave.rate 48000
slave.pcm "hw:0,0"
}
#-------------------- Slave 1 --------------------
pcm.my_dmix_loop
{
type dmix
ipc_key 1000
ipc_key_add_uid 1
ipc_perm 0600
slave.period_time 10000
slave.period_size 480
slave.buffer_size 3840
slave.rate 48000
slave.pcm my_loopback_out
}
pcm.my_loopback_out
{
type hw
card Loopback
device 0
subdevice 0
}
#*************************************************
# CAPTURE
#*************************************************
pcm.my_dsnoop_loop
{
type dsnoop
ipc_key 1000
ipc_key_add_uid 1
ipc_perm 0600
slave.period_time 10000
slave.period_size 480
slave.buffer_size 3840
slave.rate 48000
slave.pcm my_loopback_in
}
pcm.my_loopback_in
{
type hw
card Loopback
device 1
subdevice 0
}
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: loopback snd_pcm_writei
2019-04-01 13:51 loopback snd_pcm_writei Giuliano Zannetti - ART S.p.A.
@ 2019-04-09 8:36 ` Jaroslav Kysela
2019-04-24 15:50 ` R: " Giuliano Zannetti - ART S.p.A.
0 siblings, 1 reply; 3+ messages in thread
From: Jaroslav Kysela @ 2019-04-09 8:36 UTC (permalink / raw
To: Giuliano Zannetti - ART S.p.A., alsa-devel@alsa-project.org
Dne 01. 04. 19 v 15:51 Giuliano Zannetti - ART S.p.A. napsal(a):
> Hi,
>
> I have the configuration in the asound.conf above.
>
> my_plug - - > my_route - - > my_multi - - > slave0 (forward)
> - - > slave1 (loopback)
>
> I open the plug my_plug in the block mode:
>
> writtenFrames = snd_pcm_writei(handle, bufferToWrite, bufferToWriteSize);
>
> The issue I see is that there are several "writes" with 0 written frames. It seems like the snd_pcm_writei does not hold until data will be written. In general, 0 written frames sounds weird to me, because snd_pcm_writei should block itself if no space is available in the circular buffer right?
>
> I have tried to fix the following method in pcm_multi.c, as Jaroslav Kysela suggests.
>
> -static int snd_pcm_multi_may_wait_for_avail_min(snd_pcm_t *pcm, snd_pcm_uframes_t avail ATTRIBUTE_UNUSED)
> +static int snd_pcm_multi_may_wait_for_avail_min(snd_pcm_t *pcm, snd_pcm_uframes_t avail)
> {
> snd_pcm_multi_t *multi = pcm->private_data;
> - snd_pcm_t *slave = multi->slaves[multi->master_slave].pcm;
> - return snd_pcm_may_wait_for_avail_min(slave, snd_pcm_mmap_avail(slave));
> + unsigned int i;
> + for (i = 0; i < multi->slaves_count; ++i) {
> + if (snd_pcm_may_wait_for_avail_min(multi->slaves[i].pcm, avail))
> + return 1;
> + }
> + return 0;
> }
>
> But unfortunately the issue has not been resolved.
Hi,
I did some debugging (it's pretty reproducible) and the real fixes are here:
https://git.alsa-project.org/?p=alsa-lib.git;a=commit;h=4694a6643dc09c5e41969d33ed98f42278a02d40
https://git.alsa-project.org/?p=alsa-lib.git;a=commit;h=c7fc3fdbe23e63757b0e2c88c0d7c029c660923b
https://git.alsa-project.org/?p=alsa-lib.git;a=commit;h=369df322577034ea872978d6470edbadf30d81a9
https://git.alsa-project.org/?p=alsa-lib.git;a=commit;h=0bfad420efea328a50361bb3ed11487acf69da25
Just get the latest alsa-lib and it should work correctly now. Let me know the result.
Thanks.
Jaroslav
--
Jaroslav Kysela <perex@perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
^ permalink raw reply [flat|nested] 3+ messages in thread
* R: loopback snd_pcm_writei
2019-04-09 8:36 ` Jaroslav Kysela
@ 2019-04-24 15:50 ` Giuliano Zannetti - ART S.p.A.
0 siblings, 0 replies; 3+ messages in thread
From: Giuliano Zannetti - ART S.p.A. @ 2019-04-24 15:50 UTC (permalink / raw
To: Jaroslav Kysela, alsa-devel@alsa-project.org
Hi Jaroslav,
Thank you for the fix. I tried it and I don't have 0-written-frames anymore.
To be sure that the fix works fine, I compared the multi scenario (forward+loopback) with the forward-only scenario.
It works fine in both cases, but sometimes in the multi scenario I have underruns.
Could it depend from the fix? Or the usage of multi itself can bring to underruns?
-----Messaggio originale-----
Da: Jaroslav Kysela <perex@perex.cz>
Inviato: martedì 9 aprile 2019 10:37
A: Giuliano Zannetti - ART S.p.A. <giuliano.zannetti@artgroup-spa.com>; alsa-devel@alsa-project.org
Oggetto: Re: [alsa-devel] loopback snd_pcm_writei
Dne 01. 04. 19 v 15:51 Giuliano Zannetti - ART S.p.A. napsal(a):
> Hi,
>
> I have the configuration in the asound.conf above.
>
> my_plug - - > my_route - - > my_multi - - > slave0 (forward)
> - - > slave1 (loopback)
>
> I open the plug my_plug in the block mode:
>
> writtenFrames = snd_pcm_writei(handle, bufferToWrite, bufferToWriteSize);
>
> The issue I see is that there are several "writes" with 0 written frames. It seems like the snd_pcm_writei does not hold until data will be written. In general, 0 written frames sounds weird to me, because snd_pcm_writei should block itself if no space is available in the circular buffer right?
>
> I have tried to fix the following method in pcm_multi.c, as Jaroslav Kysela suggests.
>
> -static int snd_pcm_multi_may_wait_for_avail_min(snd_pcm_t *pcm, snd_pcm_uframes_t avail ATTRIBUTE_UNUSED)
> +static int snd_pcm_multi_may_wait_for_avail_min(snd_pcm_t *pcm, snd_pcm_uframes_t avail)
> {
> snd_pcm_multi_t *multi = pcm->private_data;
> - snd_pcm_t *slave = multi->slaves[multi->master_slave].pcm;
> - return snd_pcm_may_wait_for_avail_min(slave, snd_pcm_mmap_avail(slave));
> + unsigned int i;
> + for (i = 0; i < multi->slaves_count; ++i) {
> + if (snd_pcm_may_wait_for_avail_min(multi->slaves[i].pcm, avail))
> + return 1;
> + }
> + return 0;
> }
>
> But unfortunately the issue has not been resolved.
Hi,
I did some debugging (it's pretty reproducible) and the real fixes are here:
https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.alsa-project.org%2F%3Fp%3Dalsa-lib.git%3Ba%3Dcommit%3Bh%3D4694a6643dc09c5e41969d33ed98f42278a02d40&data=02%7C01%7Cgiuliano.zannetti%40artgroup-spa.com%7Ca95dd139ed42412885ec08d6bcc684ce%7C53c55efcdafd47099ce8f76299277497%7C0%7C1%7C636903958159477162&sdata=R9T2kwry3yRBJCA440vmGHFf6sTNeqblW67pCYnw1Is%3D&reserved=0
https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.alsa-project.org%2F%3Fp%3Dalsa-lib.git%3Ba%3Dcommit%3Bh%3Dc7fc3fdbe23e63757b0e2c88c0d7c029c660923b&data=02%7C01%7Cgiuliano.zannetti%40artgroup-spa.com%7Ca95dd139ed42412885ec08d6bcc684ce%7C53c55efcdafd47099ce8f76299277497%7C0%7C1%7C636903958159477162&sdata=Q06WlhuV0X2E0wrmTeYeUb9R1a3%2FVLkzC0K1dPYYqS0%3D&reserved=0
https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.alsa-project.org%2F%3Fp%3Dalsa-lib.git%3Ba%3Dcommit%3Bh%3D369df322577034ea872978d6470edbadf30d81a9&data=02%7C01%7Cgiuliano.zannetti%40artgroup-spa.com%7Ca95dd139ed42412885ec08d6bcc684ce%7C53c55efcdafd47099ce8f76299277497%7C0%7C1%7C636903958159477162&sdata=TyAfgfYoFIXNxlwH2CnBQ8cUftoHg6abCAxqtqgwfJU%3D&reserved=0
https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.alsa-project.org%2F%3Fp%3Dalsa-lib.git%3Ba%3Dcommit%3Bh%3D0bfad420efea328a50361bb3ed11487acf69da25&data=02%7C01%7Cgiuliano.zannetti%40artgroup-spa.com%7Ca95dd139ed42412885ec08d6bcc684ce%7C53c55efcdafd47099ce8f76299277497%7C0%7C1%7C636903958159477162&sdata=wfgo7N%2F6NsttszoE6fLTJ%2B4bYTMoUBLEps91qo4eIkE%3D&reserved=0
Just get the latest alsa-lib and it should work correctly now. Let me know the result.
Thanks.
Jaroslav
--
Jaroslav Kysela <perex@perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
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Alsa-devel mailing list
Alsa-devel@alsa-project.org
https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
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2019-04-01 13:51 loopback snd_pcm_writei Giuliano Zannetti - ART S.p.A.
2019-04-09 8:36 ` Jaroslav Kysela
2019-04-24 15:50 ` R: " Giuliano Zannetti - ART S.p.A.
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