[PATCH] improved snd-aloop quality when using certain samplerates and kernel HZ

[PATCH] improved snd-aloop quality when using certain samplerates and kernel HZ

[Ahmet İnan]

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after using a HZ:=300 kernel for some time now and needing snd-aloop again i
found out, that i either had to correct the hardcoded number, or fix the
problem permanently, which couses stuttering and other problems.

i also removed the SYNC on start code, not just because its more or less
useless and brings problems, but ive got a nice idea how to fix this
overrun/underrun problem in a much nicer way.

so stay tuned for the next patch, until its implemented.

this patch here is more or less experimental, id like to hear some feedback.

http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-driver-1.0.15-aloop-ainan-patch0.diff

Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>

please also include my email address when responding - i have no intention
to enable recieving emails from the list.

ahmet

--
admin der abteilung für angewandte mathematik, tel. 0761-203-5626

[-- Attachment #2: alsa-driver-1.0.15-aloop-ainan-patch0.diff --]
[-- Type: text/plain, Size: 5224 bytes --]

--- aloop-kernel-orig.c	2008-02-19 03:27:10.203115360 +0100
+++ aloop-kernel.c	2008-02-19 03:23:56.874121702 +0100
@@ -32,9 +32,6 @@
 
 /* comment in to trash your kernel logfiles */
 /* #define SND_CARD_LOOPBACK_VERBOSE */
-/* comment in for synchronization on start trigger
- * works well on alsa apps but bad on oss emulation */
-/* #define SND_CARD_LOOPBACK_START_SYNC */
 
 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
 MODULE_DESCRIPTION("A loopback soundcard");
@@ -85,16 +82,13 @@
 	snd_card_loopback_t *loopback;
 	spinlock_t lock;
 	struct timer_list timer;
-	int stream;
-	unsigned int pcm_1000_size;
-	unsigned int pcm_1000_count;
-	unsigned int pcm_size;
-	unsigned int pcm_count;
+	unsigned int pcm_size_hz;
+	unsigned int pcm_count_hz;
 	unsigned int pcm_bps;		/* bytes per second */
-	unsigned int pcm_1000_jiffie;	/* 1000 * bytes per one jiffie */
-	unsigned int pcm_1000_irq_pos;	/* IRQ position */
-	unsigned int pcm_1000_buf_pos;	/* position in buffer */
-	unsigned int pcm_period_pos;	/* period aligned pos in buffer */
+	unsigned int pcm_hz;		/* HZ */
+	unsigned int pcm_irq_pos_hz;	/* IRQ position * HZ */
+	unsigned int pcm_buf_pos_hz;	/* position in buffer * HZ */
+	unsigned int pcm_period_pos_hz;	/* period aligned pos in buffer * HZ */
 	struct snd_pcm_substream *substream;
 	struct snd_card_loopback_cable *cable;
 } snd_card_loopback_pcm_t;
@@ -123,18 +117,7 @@
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
-#ifdef SND_CARD_LOOPBACK_START_SYNC
-	snd_card_loopback_pcm_t *capture_dpcm;
-#endif
 	if (cmd == SNDRV_PCM_TRIGGER_START) {
-#ifdef SND_CARD_LOOPBACK_START_SYNC
-		if (dpcm->cable->capture_running) {
-			capture_dpcm = dpcm->cable->capture->runtime->private_data;
-			dpcm->pcm_1000_irq_pos = capture_dpcm->pcm_1000_irq_pos;
-			dpcm->pcm_1000_buf_pos = capture_dpcm->pcm_1000_buf_pos;
-			dpcm->pcm_period_pos = capture_dpcm->pcm_period_pos;
-		}
-#endif
 		dpcm->cable->playback_running = 1;
 		snd_card_loopback_timer_start(substream);
 	} else if (cmd == SNDRV_PCM_TRIGGER_STOP) {
@@ -154,18 +137,7 @@
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
-#ifdef SND_CARD_LOOPBACK_START_SYNC
-	snd_card_loopback_pcm_t *playback_dpcm;
-#endif
 	if (cmd == SNDRV_PCM_TRIGGER_START) {
-#ifdef SND_CARD_LOOPBACK_START_SYNC
-		if (dpcm->cable->playback_running) {
-			playback_dpcm = dpcm->cable->playback->runtime->private_data;
-			dpcm->pcm_1000_irq_pos = playback_dpcm->pcm_1000_irq_pos;
-			dpcm->pcm_1000_buf_pos = playback_dpcm->pcm_1000_buf_pos;
-			dpcm->pcm_period_pos = playback_dpcm->pcm_period_pos;
-		}
-#endif
 		dpcm->cable->capture_running = 1;
 		snd_card_loopback_timer_start(substream);
 	} else if (cmd == SNDRV_PCM_TRIGGER_STOP) {
@@ -190,14 +162,12 @@
 	if (bps <= 0)
 		return -EINVAL;
 	dpcm->pcm_bps = bps;
-	dpcm->pcm_1000_jiffie = (1000 * bps) / HZ;
-	dpcm->pcm_size = frames_to_bytes(runtime, runtime->buffer_size);
-	dpcm->pcm_count = frames_to_bytes(runtime, runtime->period_size);
-	dpcm->pcm_1000_size = 1000 * frames_to_bytes(runtime, runtime->buffer_size);
-	dpcm->pcm_1000_count = 1000 * frames_to_bytes(runtime, runtime->period_size);
-	dpcm->pcm_1000_irq_pos = 0;
-	dpcm->pcm_1000_buf_pos = 0;
-	dpcm->pcm_period_pos = 0;
+	dpcm->pcm_hz = HZ;
+	dpcm->pcm_size_hz = frames_to_bytes(runtime, runtime->buffer_size) * dpcm->pcm_hz;
+	dpcm->pcm_count_hz = frames_to_bytes(runtime, runtime->period_size) * dpcm->pcm_hz;
+	dpcm->pcm_irq_pos_hz = 0;
+	dpcm->pcm_buf_pos_hz = 0;
+	dpcm->pcm_period_pos_hz = 0;
 
 	cable->hw.formats = (1ULL << runtime->format);
 	cable->hw.rate_min = runtime->rate;
@@ -246,13 +216,13 @@
 	add_timer(&dpcm->timer);
 	spin_lock_irq(&dpcm->lock);
 
-	dpcm->pcm_1000_irq_pos += dpcm->pcm_1000_jiffie;
-	dpcm->pcm_1000_buf_pos += dpcm->pcm_1000_jiffie;
-	dpcm->pcm_1000_buf_pos %= dpcm->pcm_1000_size;
-	if (dpcm->pcm_1000_irq_pos >= dpcm->pcm_1000_count) {
-		dpcm->pcm_1000_irq_pos %= dpcm->pcm_1000_count;
-		dpcm->pcm_period_pos += dpcm->pcm_count;
-		dpcm->pcm_period_pos %= dpcm->pcm_size;
+	dpcm->pcm_irq_pos_hz += dpcm->pcm_bps;
+	dpcm->pcm_buf_pos_hz += dpcm->pcm_bps;
+	dpcm->pcm_buf_pos_hz %= dpcm->pcm_size_hz;
+	if (dpcm->pcm_irq_pos_hz >= dpcm->pcm_count_hz) {
+		dpcm->pcm_irq_pos_hz %= dpcm->pcm_count_hz;
+		dpcm->pcm_period_pos_hz += dpcm->pcm_count_hz;
+		dpcm->pcm_period_pos_hz %= dpcm->pcm_size_hz;
 		spin_unlock_irq(&dpcm->lock);	
 		snd_pcm_period_elapsed(dpcm->substream);
 	} else {
@@ -264,7 +234,7 @@
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
-	return bytes_to_frames(runtime, dpcm->pcm_period_pos);
+	return bytes_to_frames(runtime, dpcm->pcm_period_pos_hz / dpcm->pcm_hz);
 }
 
 static struct snd_pcm_hardware snd_card_loopback_info =
@@ -381,7 +351,6 @@
 	dpcm->timer.data = (unsigned long)dpcm;
 	dpcm->timer.function = snd_card_loopback_timer_function;
 	dpcm->cable = &loopback->cables[substream->number][half];
-	dpcm->stream = substream->stream;
 	runtime->private_data = dpcm;
 	runtime->private_free = snd_card_loopback_runtime_free;
 	runtime->hw = snd_card_loopback_info;

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Re: [PATCH] improved snd-aloop quality when using certain samplerates and kernel HZ

[Ahmet İnan]

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sorry, forget about the patch before. this one here is a lot better to read
and fixes one silly mistake.

http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-driver-1.0.15-aloop-ainan-patch1.diff
 
Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>
 
please also include my email address when responding - i have no intention
to enable recieving emails from the list.

ahmet

--
admin der abteilung für angewandte mathematik, tel. 0761-203-5626

[-- Attachment #2: alsa-driver-1.0.15-aloop-ainan-patch1.diff --]
[-- Type: text/plain, Size: 4340 bytes --]

--- aloop-kernel-orig.c	2008-02-19 03:27:10.203115360 +0100
+++ aloop-kernel.c	2008-02-19 13:39:27.040593408 +0100
@@ -32,9 +32,6 @@
 
 /* comment in to trash your kernel logfiles */
 /* #define SND_CARD_LOOPBACK_VERBOSE */
-/* comment in for synchronization on start trigger
- * works well on alsa apps but bad on oss emulation */
-/* #define SND_CARD_LOOPBACK_START_SYNC */
 
 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
 MODULE_DESCRIPTION("A loopback soundcard");
@@ -85,15 +82,12 @@
 	snd_card_loopback_t *loopback;
 	spinlock_t lock;
 	struct timer_list timer;
-	int stream;
-	unsigned int pcm_1000_size;
-	unsigned int pcm_1000_count;
 	unsigned int pcm_size;
 	unsigned int pcm_count;
 	unsigned int pcm_bps;		/* bytes per second */
-	unsigned int pcm_1000_jiffie;	/* 1000 * bytes per one jiffie */
-	unsigned int pcm_1000_irq_pos;	/* IRQ position */
-	unsigned int pcm_1000_buf_pos;	/* position in buffer */
+	unsigned int pcm_hz;		/* HZ */
+	unsigned int pcm_irq_pos;	/* IRQ position */
+	unsigned int pcm_buf_pos;	/* position in buffer */
 	unsigned int pcm_period_pos;	/* period aligned pos in buffer */
 	struct snd_pcm_substream *substream;
 	struct snd_card_loopback_cable *cable;
@@ -123,18 +117,7 @@
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
-#ifdef SND_CARD_LOOPBACK_START_SYNC
-	snd_card_loopback_pcm_t *capture_dpcm;
-#endif
 	if (cmd == SNDRV_PCM_TRIGGER_START) {
-#ifdef SND_CARD_LOOPBACK_START_SYNC
-		if (dpcm->cable->capture_running) {
-			capture_dpcm = dpcm->cable->capture->runtime->private_data;
-			dpcm->pcm_1000_irq_pos = capture_dpcm->pcm_1000_irq_pos;
-			dpcm->pcm_1000_buf_pos = capture_dpcm->pcm_1000_buf_pos;
-			dpcm->pcm_period_pos = capture_dpcm->pcm_period_pos;
-		}
-#endif
 		dpcm->cable->playback_running = 1;
 		snd_card_loopback_timer_start(substream);
 	} else if (cmd == SNDRV_PCM_TRIGGER_STOP) {
@@ -154,18 +137,7 @@
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
-#ifdef SND_CARD_LOOPBACK_START_SYNC
-	snd_card_loopback_pcm_t *playback_dpcm;
-#endif
 	if (cmd == SNDRV_PCM_TRIGGER_START) {
-#ifdef SND_CARD_LOOPBACK_START_SYNC
-		if (dpcm->cable->playback_running) {
-			playback_dpcm = dpcm->cable->playback->runtime->private_data;
-			dpcm->pcm_1000_irq_pos = playback_dpcm->pcm_1000_irq_pos;
-			dpcm->pcm_1000_buf_pos = playback_dpcm->pcm_1000_buf_pos;
-			dpcm->pcm_period_pos = playback_dpcm->pcm_period_pos;
-		}
-#endif
 		dpcm->cable->capture_running = 1;
 		snd_card_loopback_timer_start(substream);
 	} else if (cmd == SNDRV_PCM_TRIGGER_STOP) {
@@ -190,13 +162,11 @@
 	if (bps <= 0)
 		return -EINVAL;
 	dpcm->pcm_bps = bps;
-	dpcm->pcm_1000_jiffie = (1000 * bps) / HZ;
+	dpcm->pcm_hz = HZ;
 	dpcm->pcm_size = frames_to_bytes(runtime, runtime->buffer_size);
 	dpcm->pcm_count = frames_to_bytes(runtime, runtime->period_size);
-	dpcm->pcm_1000_size = 1000 * frames_to_bytes(runtime, runtime->buffer_size);
-	dpcm->pcm_1000_count = 1000 * frames_to_bytes(runtime, runtime->period_size);
-	dpcm->pcm_1000_irq_pos = 0;
-	dpcm->pcm_1000_buf_pos = 0;
+	dpcm->pcm_irq_pos = 0;
+	dpcm->pcm_buf_pos = 0;
 	dpcm->pcm_period_pos = 0;
 
 	cable->hw.formats = (1ULL << runtime->format);
@@ -246,11 +216,11 @@
 	add_timer(&dpcm->timer);
 	spin_lock_irq(&dpcm->lock);
 
-	dpcm->pcm_1000_irq_pos += dpcm->pcm_1000_jiffie;
-	dpcm->pcm_1000_buf_pos += dpcm->pcm_1000_jiffie;
-	dpcm->pcm_1000_buf_pos %= dpcm->pcm_1000_size;
-	if (dpcm->pcm_1000_irq_pos >= dpcm->pcm_1000_count) {
-		dpcm->pcm_1000_irq_pos %= dpcm->pcm_1000_count;
+	dpcm->pcm_irq_pos += dpcm->pcm_bps;
+	dpcm->pcm_buf_pos += dpcm->pcm_bps;
+	dpcm->pcm_buf_pos %= dpcm->pcm_size * dpcm->pcm_hz;
+	if (dpcm->pcm_irq_pos >= dpcm->pcm_count * dpcm->pcm_hz) {
+		dpcm->pcm_irq_pos %= dpcm->pcm_count * dpcm->pcm_hz;
 		dpcm->pcm_period_pos += dpcm->pcm_count;
 		dpcm->pcm_period_pos %= dpcm->pcm_size;
 		spin_unlock_irq(&dpcm->lock);	
@@ -381,7 +351,6 @@
 	dpcm->timer.data = (unsigned long)dpcm;
 	dpcm->timer.function = snd_card_loopback_timer_function;
 	dpcm->cable = &loopback->cables[substream->number][half];
-	dpcm->stream = substream->stream;
 	runtime->private_data = dpcm;
 	runtime->private_free = snd_card_loopback_runtime_free;
 	runtime->hw = snd_card_loopback_info;

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Re: [PATCH] improved snd-aloop quality when using certain samplerates and kernel HZ

[Takashi Iwai]

At Tue, 19 Feb 2008 13:50:46 +0100,
Ahmet İnan wrote:
> 
> sorry, forget about the patch before. this one here is a lot better to read
> and fixes one silly mistake.
> 
> http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-driver-1.0.15-aloop-ainan-patch1.diff
>  
> Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>

Looks like a good clean up.

Applied to HG tree now.  Thanks!

Takashi

Re: [PATCH] improved snd-aloop quality when using certain samplerates and kernel HZ

[Ahmet İnan]

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more cleanups.

removed some unneeded stuff.
patch is relative to current hg-tree.

http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-driver-hg-aloop-ainan-patch0.diff

Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>

btw, my "nice" idea turned out to be a bitch, again. its really funny how
worse almoust always is better. :(

ahmet

--
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[-- Attachment #2: alsa-driver-hg-aloop-ainan-patch0.diff --]
[-- Type: text/plain, Size: 1257 bytes --]

diff -r 4ce2c0f9f2ef drivers/aloop-kernel.c
--- a/drivers/aloop-kernel.c	Wed Feb 20 12:46:42 2008 +0100
+++ b/drivers/aloop-kernel.c	Wed Feb 20 15:05:16 2008 +0100
@@ -86,7 +86,6 @@ typedef struct snd_card_loopback_pcm {
 	unsigned int pcm_bps;		/* bytes per second */
 	unsigned int pcm_hz;		/* HZ */
 	unsigned int pcm_irq_pos;	/* IRQ position */
-	unsigned int pcm_buf_pos;	/* position in buffer */
 	unsigned int pcm_period_pos;	/* period aligned pos in buffer */
 	struct snd_pcm_substream *substream;
 	struct snd_card_loopback_cable *cable;
@@ -165,7 +164,6 @@ static int snd_card_loopback_prepare(str
 	dpcm->pcm_size = frames_to_bytes(runtime, runtime->buffer_size);
 	dpcm->pcm_count = frames_to_bytes(runtime, runtime->period_size);
 	dpcm->pcm_irq_pos = 0;
-	dpcm->pcm_buf_pos = 0;
 	dpcm->pcm_period_pos = 0;
 
 	cable->hw.formats = (1ULL << runtime->format);
@@ -216,8 +214,6 @@ static void snd_card_loopback_timer_func
 	spin_lock_irq(&dpcm->lock);
 
 	dpcm->pcm_irq_pos += dpcm->pcm_bps;
-	dpcm->pcm_buf_pos += dpcm->pcm_bps;
-	dpcm->pcm_buf_pos %= dpcm->pcm_size * dpcm->pcm_hz;
 	if (dpcm->pcm_irq_pos >= dpcm->pcm_count * dpcm->pcm_hz) {
 		dpcm->pcm_irq_pos %= dpcm->pcm_count * dpcm->pcm_hz;
 		dpcm->pcm_period_pos += dpcm->pcm_count;

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Re: [PATCH] improved snd-aloop quality when using certain samplerates and kernel HZ

[Takashi Iwai]

At Wed, 20 Feb 2008 15:19:06 +0100,
Ahmet İnan wrote:
> 
> more cleanups.
> 
> removed some unneeded stuff.
> patch is relative to current hg-tree.
> 
> http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-driver-hg-aloop-ainan-patch0.diff
> 
> Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>

Thanks, applied now to HG tree.


Takashi

Re: [PATCH] improved snd-aloop quality when using certain samplerates and kernel HZ

[Ahmet İnan]

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removed my old debugging macros.
renamed variables to make it more clear.

[snd-aloop - even more cleanups]
http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-driver-hg-aloop-ainan-patch1.diff
[Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>]

i promised to improve and clean up snd-dummy too, so here it is:
reused the same method to improve timing, renamed the variables,
added snd_pcm_format_set_silence on prepare.

[snd-dummy - improved timing, silence on prepare]
http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-kernel-hg-dummy-ainan-patch0.diff
[Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>]

patches are relative to current hg-tree.

ahmet

--
admin der abteilung für angewandte mathematik, tel. 0761-203-5626

[-- Attachment #2: alsa-driver-hg-aloop-ainan-patch1.diff --]
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diff -r 04f0b432fb15 drivers/aloop-kernel.c
--- a/drivers/aloop-kernel.c	Wed Feb 20 17:10:53 2008 +0100
+++ b/drivers/aloop-kernel.c	Wed Feb 20 23:50:27 2008 +0100
@@ -29,9 +29,6 @@
 #include <sound/pcm.h>
 #include <sound/initval.h>
 
-/* comment in to trash your kernel logfiles */
-/* #define SND_CARD_LOOPBACK_VERBOSE */
-
 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
 MODULE_DESCRIPTION("A loopback soundcard");
 MODULE_LICENSE("GPL");
@@ -81,12 +78,12 @@ typedef struct snd_card_loopback_pcm {
 	snd_card_loopback_t *loopback;
 	spinlock_t lock;
 	struct timer_list timer;
-	unsigned int pcm_size;
-	unsigned int pcm_count;
+	unsigned int pcm_buffer_size;
+	unsigned int pcm_period_size;
 	unsigned int pcm_bps;		/* bytes per second */
 	unsigned int pcm_hz;		/* HZ */
 	unsigned int pcm_irq_pos;	/* IRQ position */
-	unsigned int pcm_period_pos;	/* period aligned pos in buffer */
+	unsigned int pcm_buf_pos;	/* position in buffer */
 	struct snd_pcm_substream *substream;
 	struct snd_card_loopback_cable *cable;
 } snd_card_loopback_pcm_t;
@@ -161,10 +158,10 @@ static int snd_card_loopback_prepare(str
 		return -EINVAL;
 	dpcm->pcm_bps = bps;
 	dpcm->pcm_hz = HZ;
-	dpcm->pcm_size = frames_to_bytes(runtime, runtime->buffer_size);
-	dpcm->pcm_count = frames_to_bytes(runtime, runtime->period_size);
+	dpcm->pcm_buffer_size = frames_to_bytes(runtime, runtime->buffer_size);
+	dpcm->pcm_period_size = frames_to_bytes(runtime, runtime->period_size);
 	dpcm->pcm_irq_pos = 0;
-	dpcm->pcm_period_pos = 0;
+	dpcm->pcm_buf_pos = 0;
 
 	cable->hw.formats = (1ULL << runtime->format);
 	cable->hw.rate_min = runtime->rate;
@@ -189,19 +186,6 @@ static int snd_card_loopback_prepare(str
 		cable->capture_valid = 1;
 	}
 
-#ifdef SND_CARD_LOOPBACK_VERBOSE
-	printk(KERN_INFO "snd-aloop(c%dd%ds%d%c): frq=%d chs=%d fmt=%d buf=%d per=%d pers=%d\n",
-			substream->pcm->card->number,
-			substream->pcm->device,
-			substream->stream,
-			(SNDRV_PCM_STREAM_PLAYBACK == substream->stream ? 'p' : 'c'),
-			runtime->rate,
-			runtime->channels,
-			snd_pcm_format_width(runtime->format),
-			frames_to_bytes(runtime, runtime->buffer_size),
-			frames_to_bytes(runtime, runtime->period_size),
-			runtime->periods);
-#endif
 	return 0;
 }
 
@@ -214,10 +198,10 @@ static void snd_card_loopback_timer_func
 	spin_lock_irq(&dpcm->lock);
 
 	dpcm->pcm_irq_pos += dpcm->pcm_bps;
-	if (dpcm->pcm_irq_pos >= dpcm->pcm_count * dpcm->pcm_hz) {
-		dpcm->pcm_irq_pos %= dpcm->pcm_count * dpcm->pcm_hz;
-		dpcm->pcm_period_pos += dpcm->pcm_count;
-		dpcm->pcm_period_pos %= dpcm->pcm_size;
+	if (dpcm->pcm_irq_pos >= dpcm->pcm_period_size * dpcm->pcm_hz) {
+		dpcm->pcm_irq_pos %= dpcm->pcm_period_size * dpcm->pcm_hz;
+		dpcm->pcm_buf_pos += dpcm->pcm_period_size;
+		dpcm->pcm_buf_pos %= dpcm->pcm_buffer_size;
 		spin_unlock_irq(&dpcm->lock);	
 		snd_pcm_period_elapsed(dpcm->substream);
 	} else {
@@ -229,7 +213,7 @@ static snd_pcm_uframes_t snd_card_loopba
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
-	return bytes_to_frames(runtime, dpcm->pcm_period_pos);
+	return bytes_to_frames(runtime, dpcm->pcm_buf_pos);
 }
 
 static struct snd_pcm_hardware snd_card_loopback_info =
@@ -263,9 +247,6 @@ static int snd_card_loopback_hw_params(s
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
 	struct snd_dma_buffer *dmab = NULL;
 	if (NULL == dpcm->cable->dma_buffer) {
-#ifdef SND_CARD_LOOPBACK_VERBOSE
-		printk(KERN_INFO "snd-aloop: allocating dma buffer\n");
-#endif
 		dmab = kzalloc(sizeof(*dmab), GFP_KERNEL);
 		if (NULL == dmab)
 			return -ENOMEM;
@@ -302,9 +283,6 @@ static int snd_card_loopback_hw_free(str
 	if (NULL == cable->dma_buffer)
 		return 0;
 
-#ifdef SND_CARD_LOOPBACK_VERBOSE
-	printk(KERN_INFO "snd-aloop: freeing dma buffer\n");
-#endif
 	snd_dma_free_pages(cable->dma_buffer);
 	kfree(cable->dma_buffer);
 	cable->dma_buffer = NULL;

[-- Attachment #3: alsa-kernel-hg-dummy-ainan-patch0.diff --]
[-- Type: text/plain, Size: 1987 bytes --]

diff -r 97f6e4d58851 drivers/dummy.c
--- a/drivers/dummy.c	Wed Feb 20 17:13:44 2008 +0100
+++ b/drivers/dummy.c	Thu Feb 21 00:14:46 2008 +0100
@@ -181,10 +181,10 @@ struct snd_dummy_pcm {
 	struct snd_dummy *dummy;
 	spinlock_t lock;
 	struct timer_list timer;
-	unsigned int pcm_size;
-	unsigned int pcm_count;
+	unsigned int pcm_buffer_size;
+	unsigned int pcm_period_size;
 	unsigned int pcm_bps;		/* bytes per second */
-	unsigned int pcm_jiffie;	/* bytes per one jiffie */
+	unsigned int pcm_hz;		/* HZ */
 	unsigned int pcm_irq_pos;	/* IRQ position */
 	unsigned int pcm_buf_pos;	/* position in buffer */
 	struct snd_pcm_substream *substream;
@@ -238,11 +238,15 @@ static int snd_card_dummy_pcm_prepare(st
 	if (bps <= 0)
 		return -EINVAL;
 	dpcm->pcm_bps = bps;
-	dpcm->pcm_jiffie = bps / HZ;
-	dpcm->pcm_size = snd_pcm_lib_buffer_bytes(substream);
-	dpcm->pcm_count = snd_pcm_lib_period_bytes(substream);
+	dpcm->pcm_hz = HZ;
+	dpcm->pcm_buffer_size = snd_pcm_lib_buffer_bytes(substream);
+	dpcm->pcm_period_size = snd_pcm_lib_period_bytes(substream);
 	dpcm->pcm_irq_pos = 0;
 	dpcm->pcm_buf_pos = 0;
+
+	snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
+			bytes_to_samples(runtime, runtime->dma_bytes));
+
 	return 0;
 }
 
@@ -254,11 +258,11 @@ static void snd_card_dummy_pcm_timer_fun
 	spin_lock_irqsave(&dpcm->lock, flags);
 	dpcm->timer.expires = 1 + jiffies;
 	add_timer(&dpcm->timer);
-	dpcm->pcm_irq_pos += dpcm->pcm_jiffie;
-	dpcm->pcm_buf_pos += dpcm->pcm_jiffie;
-	dpcm->pcm_buf_pos %= dpcm->pcm_size;
-	if (dpcm->pcm_irq_pos >= dpcm->pcm_count) {
-		dpcm->pcm_irq_pos %= dpcm->pcm_count;
+	dpcm->pcm_irq_pos += dpcm->pcm_bps;
+	if (dpcm->pcm_irq_pos >= dpcm->pcm_period_size * dpcm->pcm_hz) {
+		dpcm->pcm_irq_pos %= dpcm->pcm_period_size * dpcm->pcm_hz;
+		dpcm->pcm_buf_pos += dpcm->pcm_period_size;
+		dpcm->pcm_buf_pos %= dpcm->pcm_buffer_size;
 		spin_unlock_irqrestore(&dpcm->lock, flags);
 		snd_pcm_period_elapsed(dpcm->substream);
 	} else

[-- Attachment #4: Type: text/plain, Size: 160 bytes --]

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Re: [PATCH] improved snd-aloop quality when using certain samplerates and kernel HZ

[Takashi Iwai]

At Thu, 21 Feb 2008 01:06:01 +0100,
Ahmet İnan wrote:
At Thu, 21 Feb 2008 01:06:01 +0100,
Ahmet İnan wrote:
> 
> [snd-aloop - even more cleanups]
> http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-driver-hg-aloop-ainan-patch1.diff
> [Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>]
> 
> i promised to improve and clean up snd-dummy too, so here it is:
> reused the same method to improve timing, renamed the variables,
> added snd_pcm_format_set_silence on prepare.
> 
> [snd-dummy - improved timing, silence on prepare]
> http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-kernel-hg-dummy-ainan-patch0.diff
> [Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>]
> 
> patches are relative to current hg-tree.

Thanks, applied both to HG tree now.


Takashi

Re: [PATCH] improved snd-aloop quality when using certain samplerates and kernel HZ

[Ahmet İnan]

[-- Attachment #1: Type: text/plain, Size: 949 bytes --]

when the time interval for a period is smaller than kernel HZ, then
snd-aloop and snd-dummy cannot call snd_pcm_period_elapsed as fast enough
annymore. this happens for example with games. but the app still needs to
see, that the buffer actually did go further, which is provided by these
patches.

[snd-aloop - better realtime app support]
http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-driver-hg-aloop-ainan-patch2.diff
[Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>]

[snd-dummy - better realtime app support]
http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-kernel-hg-dummy-ainan-patch1.diff
[Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>]

patches are relative to current hg-tree.

finally even realtime apps like games work smooth.
only one thing left for perfection :)

ahmet

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[-- Attachment #2: alsa-driver-hg-aloop-ainan-patch2.diff --]
[-- Type: text/plain, Size: 1070 bytes --]

diff -r 89222d702376 drivers/aloop-kernel.c
--- a/drivers/aloop-kernel.c	Thu Feb 21 07:54:16 2008 +0100
+++ b/drivers/aloop-kernel.c	Fri Feb 22 18:16:56 2008 +0100
@@ -198,10 +198,10 @@ static void snd_card_loopback_timer_func
 	spin_lock_irq(&dpcm->lock);
 
 	dpcm->pcm_irq_pos += dpcm->pcm_bps;
+	dpcm->pcm_buf_pos += dpcm->pcm_bps;
+	dpcm->pcm_buf_pos %= dpcm->pcm_buffer_size * dpcm->pcm_hz;
 	if (dpcm->pcm_irq_pos >= dpcm->pcm_period_size * dpcm->pcm_hz) {
 		dpcm->pcm_irq_pos %= dpcm->pcm_period_size * dpcm->pcm_hz;
-		dpcm->pcm_buf_pos += dpcm->pcm_period_size;
-		dpcm->pcm_buf_pos %= dpcm->pcm_buffer_size;
 		spin_unlock_irq(&dpcm->lock);	
 		snd_pcm_period_elapsed(dpcm->substream);
 	} else {
@@ -213,7 +213,7 @@ static snd_pcm_uframes_t snd_card_loopba
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_card_loopback_pcm_t *dpcm = runtime->private_data;
-	return bytes_to_frames(runtime, dpcm->pcm_buf_pos);
+	return bytes_to_frames(runtime, dpcm->pcm_buf_pos / dpcm->pcm_hz);
 }
 
 static struct snd_pcm_hardware snd_card_loopback_info =

[-- Attachment #3: alsa-kernel-hg-dummy-ainan-patch1.diff --]
[-- Type: text/plain, Size: 1089 bytes --]

diff -r 1d499d7e155e drivers/dummy.c
--- a/drivers/dummy.c	Thu Feb 21 12:40:00 2008 +0100
+++ b/drivers/dummy.c	Fri Feb 22 18:25:20 2008 +0100
@@ -259,10 +259,10 @@ static void snd_card_dummy_pcm_timer_fun
 	dpcm->timer.expires = 1 + jiffies;
 	add_timer(&dpcm->timer);
 	dpcm->pcm_irq_pos += dpcm->pcm_bps;
+	dpcm->pcm_buf_pos += dpcm->pcm_bps;
+	dpcm->pcm_buf_pos %= dpcm->pcm_buffer_size * dpcm->pcm_hz;
 	if (dpcm->pcm_irq_pos >= dpcm->pcm_period_size * dpcm->pcm_hz) {
 		dpcm->pcm_irq_pos %= dpcm->pcm_period_size * dpcm->pcm_hz;
-		dpcm->pcm_buf_pos += dpcm->pcm_period_size;
-		dpcm->pcm_buf_pos %= dpcm->pcm_buffer_size;
 		spin_unlock_irqrestore(&dpcm->lock, flags);
 		snd_pcm_period_elapsed(dpcm->substream);
 	} else
@@ -274,7 +274,7 @@ static snd_pcm_uframes_t snd_card_dummy_
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct snd_dummy_pcm *dpcm = runtime->private_data;
 
-	return bytes_to_frames(runtime, dpcm->pcm_buf_pos);
+	return bytes_to_frames(runtime, dpcm->pcm_buf_pos / dpcm->pcm_hz);
 }
 
 static struct snd_pcm_hardware snd_card_dummy_playback =

[-- Attachment #4: Type: text/plain, Size: 160 bytes --]

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Re: [PATCH] improved snd-aloop quality when using certain samplerates and kernel HZ

[Takashi Iwai]

At Fri, 22 Feb 2008 19:05:28 +0100,
Ahmet İnan wrote:
> 
> when the time interval for a period is smaller than kernel HZ, then
> snd-aloop and snd-dummy cannot call snd_pcm_period_elapsed as fast enough
> annymore. this happens for example with games. but the app still needs to
> see, that the buffer actually did go further, which is provided by these
> patches.

Applied to HG tree now.  Thanks.


Takashi

Re: [PATCH] improved snd-aloop quality when using certain samplerates and kernel HZ

[Ahmet İnan]

> > see, that the buffer actually did go further, which is provided by these
> > patches.
> Applied to HG tree now.  Thanks.

could it be, that you still forgot to apply this patch, but did the other?

[snd-aloop - better realtime app support]
http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-driver-hg-aloop-ainan-patch2.diff
[Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>]

or you havent synced home alsa-driver with main repository yet,
then never mind :)

thanks

ahmet

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Re: [PATCH] improved snd-aloop quality when using certain samplerates and kernel HZ

[Takashi Iwai]

At Sat, 1 Mar 2008 12:55:06 +0100,
Ahmet İnan wrote:
> 
> > > see, that the buffer actually did go further, which is provided by these
> > > patches.
> > Applied to HG tree now.  Thanks.
> 
> could it be, that you still forgot to apply this patch, but did the other?

It was already applied but a different subject.
Please follow the standard patch style at the next time.


Takashi

Re: [PATCH] improved snd-aloop quality when using certain samplerates and kernel HZ

[Ahmet İnan]

moved module parameter pcm_substreams range check code around, to prevent catastrophe.
removed bogus module parameter pcm_devs code - aloop creates only one pair of devices.
allowed float_le, too.
removed obsolete code.

[snd-aloop - more cleanups]
http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-driver-hg-aloop-ainan-patch3.diff
[Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>]

patch is relative to my previous patch.

will fix bogus wiki entries, about the module parameters, too.

ahmet

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Re: [PATCH] improved snd-aloop quality when using certain samplerates and kernel HZ

[Takashi Iwai]

At Sun, 2 Mar 2008 00:35:03 +0100,
Ahmet İnan wrote:
> 
> moved module parameter pcm_substreams range check code around, to prevent catastrophe.
> removed bogus module parameter pcm_devs code - aloop creates only one pair of devices.
> allowed float_le, too.
> removed obsolete code.
> 
> [snd-aloop - more cleanups]
> http://www.mathematik.uni-freiburg.de/IAM/homepages/ainan/alsa-driver-hg-aloop-ainan-patch3.diff
> [Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>]
> 
> patch is relative to my previous patch.

Please post the patch instead of URL.

Also, it'd be appreciated if you follow the standard rule for
submitting patches.  We follow the linux kernel rule for alsa-driver
tree, too.  See $LINUX/Documentation/SubmittingPatches.


thanks,

Takashi

Re: [PATCH] improved snd-aloop quality when using certain samplerates and kernel HZ

[Ahmet İnan]

[-- Attachment #1: Type: text/plain, Size: 490 bytes --]

> Also, it'd be appreciated if you follow the standard rule for
thank you for pointing this out. will try my best.
patch is relative to current hg-tree.

ahmet

snd-aloop - more cleanups

moved module parameter pcm_substreams range check code around, to prevent catastrophe.
removed bogus module parameter pcm_devs code - aloop creates only one pair of devices.
allowed float_le, too.
removed obsolete code.

Signed-off-by: Ahmet İnan <ainan <at> mathematik.uni-freiburg.de>

[-- Attachment #2: alsa-driver-hg-aloop-ainan-patch5.diff --]
[-- Type: text/plain, Size: 3903 bytes --]

diff -r 6def4892d3f5 drivers/aloop-kernel.c
--- a/drivers/aloop-kernel.c	Mon Mar 03 11:05:48 2008 +0100
+++ b/drivers/aloop-kernel.c	Thu Mar 06 21:24:24 2008 +0100
@@ -39,9 +39,7 @@ static int index[SNDRV_CARDS] = SNDRV_DE
 static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;	/* Index 0-MAX */
 static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;	/* ID for this card */
 static int enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
-static int pcm_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 1};
 static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};
-/* static int midi_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 2}; */
 
 module_param_array(index, int, NULL, 0444);
 MODULE_PARM_DESC(index, "Index value for loopback soundcard.");
@@ -49,12 +47,8 @@ MODULE_PARM_DESC(id, "ID string for loop
 MODULE_PARM_DESC(id, "ID string for loopback soundcard.");
 module_param_array(enable, bool, NULL, 0444);
 MODULE_PARM_DESC(enable, "Enable this loopback soundcard.");
-module_param_array(pcm_devs, int, NULL, 0444);
-MODULE_PARM_DESC(pcm_devs, "PCM devices # (0-4) for loopback driver.");
 module_param_array(pcm_substreams, int, NULL, 0444);
 MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-8) for loopback driver.");
-/* module_param_array(midi_devs, int, NULL, 0444);
- * MODULE_PARM_DESC(midi_devs, "MIDI devices # (0-2) for loopback driver."); */
 
 typedef struct snd_card_loopback_cable {
 	struct snd_pcm_substream *playback;
@@ -220,7 +214,8 @@ static struct snd_pcm_hardware snd_card_
 {
 	.info =			(SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_INTERLEAVED |
 				 SNDRV_PCM_INFO_MMAP_VALID),
-	.formats =		(SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S32_LE),
+	.formats =		(SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S16_LE |
+				 SNDRV_PCM_FMTBIT_S32_LE | SNDRV_PCM_FMTBIT_FLOAT_LE),
 	.rates =		(SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_192000),
 	.rate_min =		8000,
 	.rate_max =		192000,
@@ -395,17 +390,11 @@ static int __init snd_card_loopback_pcm(
 	struct snd_pcm *pcm;
 	int err;
 
-	if (0 == device) {
-		if ((err = snd_pcm_new(loopback->card, "Loopback PCM", device, substreams, substreams, &pcm)) < 0)
-			return err;
-		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &snd_card_loopback_playback_ops);
-		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_card_loopback_capture_ops);
-	} else {
-		if ((err = snd_pcm_new(loopback->card, "Loopback PCM", device, substreams, substreams, &pcm)) < 0)
-			return err;
-		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &snd_card_loopback_playback_ops);
-		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_card_loopback_capture_ops);
-	}
+	if ((err = snd_pcm_new(loopback->card, "Loopback PCM", device, substreams, substreams, &pcm)) < 0)
+		return err;
+	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &snd_card_loopback_playback_ops);
+	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_card_loopback_capture_ops);
+
 	pcm->private_data = loopback;
 	pcm->info_flags = 0;
 	strcpy(pcm->name, "Loopback PCM");
@@ -435,6 +424,11 @@ static int __init snd_card_loopback_prob
 		return -ENOMEM;
 	loopback = (struct snd_card_loopback *)card->private_data;
 
+	if (pcm_substreams[dev] < 1)
+		pcm_substreams[dev] = 1;
+	if (pcm_substreams[dev] > MAX_PCM_SUBSTREAMS)
+		pcm_substreams[dev] = MAX_PCM_SUBSTREAMS;
+
 	for (subdev = 0; subdev < pcm_substreams[dev]; subdev++) {
 		for (half = 0; half < 2; half++) {
 			loopback->cables[subdev][half].playback = NULL;
@@ -450,10 +444,6 @@ static int __init snd_card_loopback_prob
 	}
 	
 	loopback->card = card;
-	if (pcm_substreams[dev] < 1)
-		pcm_substreams[dev] = 1;
-	if (pcm_substreams[dev] > MAX_PCM_SUBSTREAMS)
-		pcm_substreams[dev] = MAX_PCM_SUBSTREAMS;
 	if ((err = snd_card_loopback_pcm(loopback, 0, pcm_substreams[dev])) < 0)
 		goto __nodev;
 	if ((err = snd_card_loopback_pcm(loopback, 1, pcm_substreams[dev])) < 0)

[-- Attachment #3: Type: text/plain, Size: 160 bytes --]

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Re: Problem with aloop

[Ahmet İnan]

ive just read about aloop problems by chance, so excuse the late answer,
for ive disabled recieving mails from this list. so also cc me when replying :)

> repeating stuttering
try tickless kernel, as it improves the quality of timer interrupts dramatically.
dont forget to enable high resolution timer support, hpet and so on.

> synchronization issue at the beginning
this is still not resolved and its a pain in the ass to get this done right.
ive implemented 4 different ways to solve it and im still not happy with what ive got.

> kernel crash when closing
do you really have to put at this manny places this del_timer?
try to find the right place and resubmit. :)

ahmet

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Re: Problem with aloop

[Benjamin van den Hout]

Hi Ahmet,

ive just read about aloop problems by chance, so excuse the late answer,
> for ive disabled recieving mails from this list. so also cc me when
> replying :)
>

No problem, I'm delighted somebody is answering my e-mails at all :)

> repeating stuttering
> try tickless kernel, as it improves the quality of timer interrupts
> dramatically.
> dont forget to enable high resolution timer support, hpet and so on.
>

OK, excellent tip. Thanks! High resolution timer support is already enabled
and I've got the kernel configured for "realtime" performance (CONFIG_HZ or
whatever it was called set to 1000 etc.). I'll try to see if the tickless
kernel makes any difference.


> > synchronization issue at the beginning
> this is still not resolved and its a pain in the ass to get this done
> right.
> ive implemented 4 different ways to solve it and im still not happy with
> what ive got.
>

The funny thing is, after I reverted to the 10.0.16 release tarball these
stuttering problems went away. So the fixes that were committed in
february/march under the 'fixes realtime behaviour' label actually made
things much worse..


> > kernel crash when closing
> do you really have to put at this manny places this del_timer?
> try to find the right place and resubmit. :)
>

I already presumed it was a bit much, I'll be the last one to deny that! ;-)

But then again, I'm not too familiar with ALSA kernel stuff anyway and the
existing documentation seems a bit sparse. Also, this patch was made as part
of a time-limited project at my company so I sadly couldn't spend more time
on it after I (crudely) fixed the bug. However, I'd love to refine my patch
(in my own spare time). Can you give me any pointers perhaps? They would be
greatly appreciated.

Thanks for taking the time to reply!

Kind regards,
Benjamin

Re: Problem with aloop

[Ahmet İnan]

> > > synchronization issue at the beginning
> > this is still not resolved and its a pain in the ass to get this done
> The funny thing is, after I reverted to the 10.0.16 release tarball these
> stuttering problems went away. So the fixes that were committed in
> february/march under the 'fixes realtime behaviour' label actually made
> things much worse..
without SND_CARD_LOOPBACK_START_SYNC, its still the same. you should really
get a tickless kernel first. otherwise its just pure luck and frustration.

> > try to find the right place and resubmit. :)
> (in my own spare time). Can you give me any pointers perhaps? They would be
usually snd_card_loopback_playback_trigger gets called with
SNDRV_PCM_TRIGGER_STOP whenever the device is about to be closed.
so the next function would be snd_card_loopback_close. try
snd_card_loopback_timer_stop there and report :D

ahmet

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