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
--- 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@xxxxxxxx>");
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;
_______________________________________________
Alsa-devel mailing list
Alsa-devel@xxxxxxxxxxxxxxxx
http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
