[PATCH] pcm: support for audio wallclock

[PATCH] pcm: support for audio wallclock

[Pierre-Louis Bossart]

add new snd_pcm_status_get_htstamp_wallclk() routine to
query the audio timestamps read from the wallclock.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
---
 include/pcm.h          |    1 +
 include/sound/asound.h |    7 ++++++-
 src/pcm/pcm.c          |   16 ++++++++++++++++
 3 files changed, 23 insertions(+), 1 deletions(-)

diff --git a/include/pcm.h b/include/pcm.h
index 4997557..325c0ea 100644
--- a/include/pcm.h
+++ b/include/pcm.h
@@ -858,6 +858,7 @@ void snd_pcm_status_get_trigger_tstamp(const snd_pcm_status_t *obj, snd_timestam
 void snd_pcm_status_get_trigger_htstamp(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr);
 void snd_pcm_status_get_tstamp(const snd_pcm_status_t *obj, snd_timestamp_t *ptr);
 void snd_pcm_status_get_htstamp(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr);
+void snd_pcm_status_get_htstamp_wallclk(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr);
 snd_pcm_sframes_t snd_pcm_status_get_delay(const snd_pcm_status_t *obj);
 snd_pcm_uframes_t snd_pcm_status_get_avail(const snd_pcm_status_t *obj);
 snd_pcm_uframes_t snd_pcm_status_get_avail_max(const snd_pcm_status_t *obj);
diff --git a/include/sound/asound.h b/include/sound/asound.h
index 07c03fa..c186fd6 100644
--- a/include/sound/asound.h
+++ b/include/sound/asound.h
@@ -285,6 +285,7 @@ enum sndrv_pcm_subformat {
 #define SNDRV_PCM_INFO_JOINT_DUPLEX	0x00200000	/* playback and capture stream are somewhat correlated */
 #define SNDRV_PCM_INFO_SYNC_START	0x00400000	/* pcm support some kind of sync go */
 #define SNDRV_PCM_INFO_NO_PERIOD_WAKEUP	0x00800000	/* period wakeup can be disabled */
+#define SNDRV_PCM_INFO_HAS_WALL_CLOCK   0x01000000      /* has audio wall clock for audio/system time sync */
 
 enum sndrv_pcm_state {
 	SNDRV_PCM_STATE_OPEN = 0,	/* stream is open */
@@ -426,7 +427,10 @@ struct sndrv_pcm_status {
 	sndrv_pcm_uframes_t avail_max;	/* max frames available on hw since last status */
 	sndrv_pcm_uframes_t overrange;	/* count of ADC (capture) overrange detections from last status */
 	int suspended_state;		/* suspended stream state */
-	unsigned char reserved[60];	/* must be filled with zero */
+	union {
+		unsigned char reserved[60];	/* must be filled with zero */
+		struct timespec audio_tstamp;	/* audio wall clock timestamp */
+	} ext;
 };
 
 struct sndrv_pcm_mmap_status {
@@ -434,6 +438,7 @@ struct sndrv_pcm_mmap_status {
 	int pad1;			/* Needed for 64 bit alignment */
 	sndrv_pcm_uframes_t hw_ptr;	/* RO: hw ptr (0...boundary-1) */
 	struct timespec tstamp;		/* Timestamp */
+	struct timespec audio_tstamp;	/* audio wall clock timestamp */
 	int suspended_state;		/* RO: suspended stream state */
 };
 
diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c
index 18b43b3..2221865 100644
--- a/src/pcm/pcm.c
+++ b/src/pcm/pcm.c
@@ -6213,6 +6213,22 @@ void snd_pcm_status_get_htstamp(const snd_pcm_status_t *obj, snd_htimestamp_t *p
 use_default_symbol_version(__snd_pcm_status_get_htstamp, snd_pcm_status_get_htstamp, ALSA_0.9.0rc8);
 
 /** 
+ * \brief Get "now" hi-res audio wallclock timestamp from a PCM status container
+ * \param obj pointer to #snd_pcm_status_t
+ * \param ptr Pointer to returned timestamp
+ */
+#ifndef DOXYGEN
+void INTERNAL(snd_pcm_status_get_htstamp_wallclk)(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr)
+#else
+void snd_pcm_status_get_htstamp_wallclk(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr)
+#endif
+{
+	assert(obj && ptr);
+	*ptr = obj->ext.audio_tstamp;
+}
+use_default_symbol_version(__snd_pcm_status_get_htstamp_wallclk, snd_pcm_status_get_htstamp_wallclk, ALSA_0.9.0rc8);  /* FIXME, no idea why this is needed */
+
+/**
  * \brief Get delay from a PCM status container (see #snd_pcm_delay)
  * \return Delay in frames
  *
-- 
1.7.6.5

Re: [PATCH] pcm: support for audio wallclock

[Takashi Iwai]

At Wed, 13 Jun 2012 15:27:47 -0500,
Pierre-Louis Bossart wrote:
> 
> add new snd_pcm_status_get_htstamp_wallclk() routine to
> query the audio timestamps read from the wallclock.
> 
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
> ---
>  include/pcm.h          |    1 +
>  include/sound/asound.h |    7 ++++++-
>  src/pcm/pcm.c          |   16 ++++++++++++++++
>  3 files changed, 23 insertions(+), 1 deletions(-)
> 
> diff --git a/include/pcm.h b/include/pcm.h
> index 4997557..325c0ea 100644
> --- a/include/pcm.h
> +++ b/include/pcm.h
> @@ -858,6 +858,7 @@ void snd_pcm_status_get_trigger_tstamp(const snd_pcm_status_t *obj, snd_timestam
>  void snd_pcm_status_get_trigger_htstamp(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr);
>  void snd_pcm_status_get_tstamp(const snd_pcm_status_t *obj, snd_timestamp_t *ptr);
>  void snd_pcm_status_get_htstamp(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr);
> +void snd_pcm_status_get_htstamp_wallclk(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr);
>  snd_pcm_sframes_t snd_pcm_status_get_delay(const snd_pcm_status_t *obj);
>  snd_pcm_uframes_t snd_pcm_status_get_avail(const snd_pcm_status_t *obj);
>  snd_pcm_uframes_t snd_pcm_status_get_avail_max(const snd_pcm_status_t *obj);
> diff --git a/include/sound/asound.h b/include/sound/asound.h
> index 07c03fa..c186fd6 100644
> --- a/include/sound/asound.h
> +++ b/include/sound/asound.h
> @@ -285,6 +285,7 @@ enum sndrv_pcm_subformat {
>  #define SNDRV_PCM_INFO_JOINT_DUPLEX	0x00200000	/* playback and capture stream are somewhat correlated */
>  #define SNDRV_PCM_INFO_SYNC_START	0x00400000	/* pcm support some kind of sync go */
>  #define SNDRV_PCM_INFO_NO_PERIOD_WAKEUP	0x00800000	/* period wakeup can be disabled */
> +#define SNDRV_PCM_INFO_HAS_WALL_CLOCK   0x01000000      /* has audio wall clock for audio/system time sync */
>  
>  enum sndrv_pcm_state {
>  	SNDRV_PCM_STATE_OPEN = 0,	/* stream is open */
> @@ -426,7 +427,10 @@ struct sndrv_pcm_status {
>  	sndrv_pcm_uframes_t avail_max;	/* max frames available on hw since last status */
>  	sndrv_pcm_uframes_t overrange;	/* count of ADC (capture) overrange detections from last status */
>  	int suspended_state;		/* suspended stream state */
> -	unsigned char reserved[60];	/* must be filled with zero */
> +	union {
> +		unsigned char reserved[60];	/* must be filled with zero */
> +		struct timespec audio_tstamp;	/* audio wall clock timestamp */
> +	} ext;
>  };
>  
>  struct sndrv_pcm_mmap_status {
> @@ -434,6 +438,7 @@ struct sndrv_pcm_mmap_status {
>  	int pad1;			/* Needed for 64 bit alignment */
>  	sndrv_pcm_uframes_t hw_ptr;	/* RO: hw ptr (0...boundary-1) */
>  	struct timespec tstamp;		/* Timestamp */
> +	struct timespec audio_tstamp;	/* audio wall clock timestamp */
>  	int suspended_state;		/* RO: suspended stream state */
>  };
>  
> diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c
> index 18b43b3..2221865 100644
> --- a/src/pcm/pcm.c
> +++ b/src/pcm/pcm.c
> @@ -6213,6 +6213,22 @@ void snd_pcm_status_get_htstamp(const snd_pcm_status_t *obj, snd_htimestamp_t *p
>  use_default_symbol_version(__snd_pcm_status_get_htstamp, snd_pcm_status_get_htstamp, ALSA_0.9.0rc8);

You need to provide a function to indicate whether htstamp_wallclk is
available or not.  Since the function returning tstamp_wallclk is a
void function and it itself can't return the error, user can't know
whether it's a bogus value or not.

And that function should check whether the running PCM protocol
version is high enough to support the new ABI.

>  /** 
> + * \brief Get "now" hi-res audio wallclock timestamp from a PCM status container
> + * \param obj pointer to #snd_pcm_status_t
> + * \param ptr Pointer to returned timestamp
> + */
> +#ifndef DOXYGEN
> +void INTERNAL(snd_pcm_status_get_htstamp_wallclk)(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr)
> +#else
> +void snd_pcm_status_get_htstamp_wallclk(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr)
> +#endif

I think you can avoid this hack for the new functions.

> +{
> +	assert(obj && ptr);
> +	*ptr = obj->ext.audio_tstamp;
> +}
> +use_default_symbol_version(__snd_pcm_status_get_htstamp_wallclk, snd_pcm_status_get_htstamp_wallclk, ALSA_0.9.0rc8);  /* FIXME, no idea why this is needed */

Ditto.  It was needed just for those functions that have been added to
0.9.0rc8 release.


Takashi

Re: [PATCH] pcm: support for audio wallclock

[Pierre-Louis Bossart]

> You need to provide a function to indicate whether htstamp_wallclk is
> available or not.  Since the function returning tstamp_wallclk is a
> void function and it itself can't return the error, user can't know
> whether it's a bogus value or not.

Yes, this was planned but I wasn't sure how to go about it. These types 
of routines usually rely on hw_params, I guess I could query them and 
check the .info field. Not sure if there's another way.
Also maybe I should change the return type to provide -EINVAL is somehow 
the audio timestamp is not available for a specific device (digital 
input as Clemens mentioned)


> And that function should check whether the running PCM protocol
> version is high enough to support the new ABI.
Yep


\
>> +#ifndef DOXYGEN
>> +void INTERNAL(snd_pcm_status_get_htstamp_wallclk)(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr)
>> +#else
>> +void snd_pcm_status_get_htstamp_wallclk(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr)
>> +#endif
>
> I think you can avoid this hack for the new functions.

Ok, I have no idea what I am doing here, just copy-pasted to make it work...

[PATCH] pcm: support for audio wallclock

[Pierre-Louis Bossart]

add new snd_pcm_status_get_htstamp_wallclk() routine to
query the audio timestamps read from the wallclock.
Also add snd_pcm_hw_params_supports_audio_wallclock_ts()
to query what the hardware supports.

TODO: check protocol compatibility?

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
---
 include/pcm.h          |    2 ++
 include/sound/asound.h |    7 +++++--
 src/pcm/pcm.c          |   31 +++++++++++++++++++++++++++++++
 3 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/include/pcm.h b/include/pcm.h
index 4997557..542d9a8 100644
--- a/include/pcm.h
+++ b/include/pcm.h
@@ -550,6 +550,7 @@ int snd_pcm_hw_params_is_half_duplex(const snd_pcm_hw_params_t *params);
 int snd_pcm_hw_params_is_joint_duplex(const snd_pcm_hw_params_t *params);
 int snd_pcm_hw_params_can_sync_start(const snd_pcm_hw_params_t *params);
 int snd_pcm_hw_params_can_disable_period_wakeup(const snd_pcm_hw_params_t *params);
+int snd_pcm_hw_params_supports_audio_wallclock_ts(const snd_pcm_hw_params_t *params);
 int snd_pcm_hw_params_get_rate_numden(const snd_pcm_hw_params_t *params,
 				      unsigned int *rate_num,
 				      unsigned int *rate_den);
@@ -858,6 +859,7 @@ void snd_pcm_status_get_trigger_tstamp(const snd_pcm_status_t *obj, snd_timestam
 void snd_pcm_status_get_trigger_htstamp(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr);
 void snd_pcm_status_get_tstamp(const snd_pcm_status_t *obj, snd_timestamp_t *ptr);
 void snd_pcm_status_get_htstamp(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr);
+void snd_pcm_status_get_htstamp_wallclk(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr);
 snd_pcm_sframes_t snd_pcm_status_get_delay(const snd_pcm_status_t *obj);
 snd_pcm_uframes_t snd_pcm_status_get_avail(const snd_pcm_status_t *obj);
 snd_pcm_uframes_t snd_pcm_status_get_avail_max(const snd_pcm_status_t *obj);
diff --git a/include/sound/asound.h b/include/sound/asound.h
index 07c03fa..f0d23d6 100644
--- a/include/sound/asound.h
+++ b/include/sound/asound.h
@@ -160,7 +160,7 @@ enum {
  *                                                                           *
  *****************************************************************************/
 
-#define SNDRV_PCM_VERSION		SNDRV_PROTOCOL_VERSION(2, 0, 10)
+#define SNDRV_PCM_VERSION		SNDRV_PROTOCOL_VERSION(2, 0, 11)
 
 typedef unsigned long sndrv_pcm_uframes_t;
 typedef long sndrv_pcm_sframes_t;
@@ -285,6 +285,7 @@ enum sndrv_pcm_subformat {
 #define SNDRV_PCM_INFO_JOINT_DUPLEX	0x00200000	/* playback and capture stream are somewhat correlated */
 #define SNDRV_PCM_INFO_SYNC_START	0x00400000	/* pcm support some kind of sync go */
 #define SNDRV_PCM_INFO_NO_PERIOD_WAKEUP	0x00800000	/* period wakeup can be disabled */
+#define SNDRV_PCM_INFO_HAS_WALL_CLOCK   0x01000000      /* has audio wall clock for audio/system time sync */
 
 enum sndrv_pcm_state {
 	SNDRV_PCM_STATE_OPEN = 0,	/* stream is open */
@@ -426,7 +427,8 @@ struct sndrv_pcm_status {
 	sndrv_pcm_uframes_t avail_max;	/* max frames available on hw since last status */
 	sndrv_pcm_uframes_t overrange;	/* count of ADC (capture) overrange detections from last status */
 	int suspended_state;		/* suspended stream state */
-	unsigned char reserved[60];	/* must be filled with zero */
+	struct timespec audio_tstamp;	/* audio wall clock timestamp */
+	unsigned char reserved[60-sizeof(struct timespec)]; /* must be filled with zero */
 };
 
 struct sndrv_pcm_mmap_status {
@@ -435,6 +437,7 @@ struct sndrv_pcm_mmap_status {
 	sndrv_pcm_uframes_t hw_ptr;	/* RO: hw ptr (0...boundary-1) */
 	struct timespec tstamp;		/* Timestamp */
 	int suspended_state;		/* RO: suspended stream state */
+	struct timespec audio_tstamp;	/* audio wall clock timestamp */
 };
 
 struct sndrv_pcm_mmap_control {
diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c
index 18b43b3..49d7b99 100644
--- a/src/pcm/pcm.c
+++ b/src/pcm/pcm.c
@@ -3123,6 +3123,26 @@ int snd_pcm_hw_params_can_disable_period_wakeup(const snd_pcm_hw_params_t *param
 }
 
 /**
+ * \brief Check if hardware supports audio wallclock timestamps
+ * \param params Configuration space
+ * \retval 0 Hardware doesn't support audio wallclock timestamps
+ * \retval 1 Hardware supports audio wallclock timestamps
+ *
+ * This function should only be called when the configuration space
+ * contains a single configuration. Call #snd_pcm_hw_params to choose
+ * a single configuration from the configuration space.
+ */
+int snd_pcm_hw_params_supports_audio_wallclock_ts(const snd_pcm_hw_params_t *params)
+{
+	assert(params);
+	if (CHECK_SANITY(params->info == ~0U)) {
+		SNDMSG("invalid PCM info field");
+		return 0; /* FIXME: should be a negative error? */
+	}
+	return !!(params->info & SNDRV_PCM_INFO_HAS_WALL_CLOCK);
+}
+
+/**
  * \brief Get rate exact info from a configuration space
  * \param params Configuration space
  * \param rate_num Pointer to returned rate numerator
@@ -6213,6 +6233,17 @@ void snd_pcm_status_get_htstamp(const snd_pcm_status_t *obj, snd_htimestamp_t *p
 use_default_symbol_version(__snd_pcm_status_get_htstamp, snd_pcm_status_get_htstamp, ALSA_0.9.0rc8);
 
 /** 
+ * \brief Get "now" hi-res audio wallclock timestamp from a PCM status container
+ * \param obj pointer to #snd_pcm_status_t
+ * \param ptr Pointer to returned timestamp
+ */
+void snd_pcm_status_get_htstamp_wallclk(const snd_pcm_status_t *obj, snd_htimestamp_t *ptr)
+{
+	assert(obj && ptr);
+	*ptr = obj->audio_tstamp;
+}
+
+/**
  * \brief Get delay from a PCM status container (see #snd_pcm_delay)
  * \return Delay in frames
  *
-- 
1.7.6.5