Hi Pierre,
sorry for the long delay.
This seems to make a lot of sense, but a question - does this impose a
requirement on a certain version of alsa-lib and/or the linux kernel?
// David
2012-07-30 02:46, Pierre-Louis Bossart skrev:
> Refactor code to fetch avail, delay and timestamp values
> in a single call to snd_pcm_status().
> The information reported is exactly the same as before,
> however it is extracted in a more atomic manner to
> improve timer-based scheduling.
>
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
> ---
> src/modules/alsa/alsa-sink.c | 12 ++++--------
> src/modules/alsa/alsa-source.c | 12 ++++--------
> src/modules/alsa/alsa-util.c | 17 ++++++++++++-----
> src/modules/alsa/alsa-util.h | 2 +-
> 4 files changed, 21 insertions(+), 22 deletions(-)
>
> diff --git a/src/modules/alsa/alsa-sink.c b/src/modules/alsa/alsa-sink.c
> index 544399e..e4baa1f 100644
> --- a/src/modules/alsa/alsa-sink.c
> +++ b/src/modules/alsa/alsa-sink.c
> @@ -825,6 +825,7 @@ static void update_smoother(struct userdata *u) {
> int err;
> pa_usec_t now1 = 0, now2;
> snd_pcm_status_t *status;
> + snd_htimestamp_t htstamp = { 0, 0 };
>
> snd_pcm_status_alloca(&status);
>
> @@ -833,18 +834,13 @@ static void update_smoother(struct userdata *u) {
>
> /* Let's update the time smoother */
>
> - if (PA_UNLIKELY((err = pa_alsa_safe_delay(u->pcm_handle, &delay, u->hwbuf_size, &u->sink->sample_spec, FALSE)) < 0)) {
> + if (PA_UNLIKELY((err = pa_alsa_safe_delay(u->pcm_handle, status, &delay, u->hwbuf_size, &u->sink->sample_spec, FALSE)) < 0)) {
> pa_log_warn("Failed to query DSP status data: %s", pa_alsa_strerror(err));
> return;
> }
>
> - if (PA_UNLIKELY((err = snd_pcm_status(u->pcm_handle, status)) < 0))
> - pa_log_warn("Failed to get timestamp: %s", pa_alsa_strerror(err));
> - else {
> - snd_htimestamp_t htstamp = { 0, 0 };
> - snd_pcm_status_get_htstamp(status, &htstamp);
> - now1 = pa_timespec_load(&htstamp);
> - }
> + snd_pcm_status_get_htstamp(status, &htstamp);
> + now1 = pa_timespec_load(&htstamp);
>
> /* Hmm, if the timestamp is 0, then it wasn't set and we take the current time */
> if (now1 <= 0)
> diff --git a/src/modules/alsa/alsa-source.c b/src/modules/alsa/alsa-source.c
> index 94d4a09..17566e7 100644
> --- a/src/modules/alsa/alsa-source.c
> +++ b/src/modules/alsa/alsa-source.c
> @@ -767,6 +767,7 @@ static void update_smoother(struct userdata *u) {
> int err;
> pa_usec_t now1 = 0, now2;
> snd_pcm_status_t *status;
> + snd_htimestamp_t htstamp = { 0, 0 };
>
> snd_pcm_status_alloca(&status);
>
> @@ -775,18 +776,13 @@ static void update_smoother(struct userdata *u) {
>
> /* Let's update the time smoother */
>
> - if (PA_UNLIKELY((err = pa_alsa_safe_delay(u->pcm_handle, &delay, u->hwbuf_size, &u->source->sample_spec, TRUE)) < 0)) {
> + if (PA_UNLIKELY((err = pa_alsa_safe_delay(u->pcm_handle, status, &delay, u->hwbuf_size, &u->source->sample_spec, TRUE)) < 0)) {
> pa_log_warn("Failed to get delay: %s", pa_alsa_strerror(err));
> return;
> }
>
> - if (PA_UNLIKELY((err = snd_pcm_status(u->pcm_handle, status)) < 0))
> - pa_log_warn("Failed to get timestamp: %s", pa_alsa_strerror(err));
> - else {
> - snd_htimestamp_t htstamp = { 0, 0 };
> - snd_pcm_status_get_htstamp(status, &htstamp);
> - now1 = pa_timespec_load(&htstamp);
> - }
> + snd_pcm_status_get_htstamp(status, &htstamp);
> + now1 = pa_timespec_load(&htstamp);
>
> /* Hmm, if the timestamp is 0, then it wasn't set and we take the current time */
> if (now1 <= 0)
> diff --git a/src/modules/alsa/alsa-util.c b/src/modules/alsa/alsa-util.c
> index bb4e307..4a29a9a 100644
> --- a/src/modules/alsa/alsa-util.c
> +++ b/src/modules/alsa/alsa-util.c
> @@ -1141,10 +1141,11 @@ snd_pcm_sframes_t pa_alsa_safe_avail(snd_pcm_t *pcm, size_t hwbuf_size, const pa
> return n;
> }
>
> -int pa_alsa_safe_delay(snd_pcm_t *pcm, snd_pcm_sframes_t *delay, size_t hwbuf_size, const pa_sample_spec *ss, pa_bool_t capture) {
> +int pa_alsa_safe_delay(snd_pcm_t *pcm, snd_pcm_status_t *status, snd_pcm_sframes_t *delay, size_t hwbuf_size, const pa_sample_spec *ss,
> + pa_bool_t capture) {
> ssize_t k;
> size_t abs_k;
> - int r;
> + int err;
> snd_pcm_sframes_t avail = 0;
>
> pa_assert(pcm);
> @@ -1154,10 +1155,16 @@ int pa_alsa_safe_delay(snd_pcm_t *pcm, snd_pcm_sframes_t *delay, size_t hwbuf_si
>
> /* Some ALSA driver expose weird bugs, let's inform the user about
> * what is going on. We're going to get both the avail and delay values so
> - * that we can compare and check them for capture */
> + * that we can compare and check them for capture.
> + * This is done with snd_pcm_status() which provides
> + * avail, delay and timestamp values in a single kernel call to improve
> + * timer-based scheduling */
>
> - if ((r = snd_pcm_avail_delay(pcm, &avail, delay)) < 0)
> - return r;
> + if ((err = snd_pcm_status(pcm, status)) < 0)
> + return err;
> +
> + avail = snd_pcm_status_get_avail(status);
> + *delay = snd_pcm_status_get_delay(status);
>
> k = (ssize_t) *delay * (ssize_t) pa_frame_size(ss);
>
> diff --git a/src/modules/alsa/alsa-util.h b/src/modules/alsa/alsa-util.h
> index a4beed2..236a329 100644
> --- a/src/modules/alsa/alsa-util.h
> +++ b/src/modules/alsa/alsa-util.h
> @@ -125,7 +125,7 @@ int pa_alsa_recover_from_poll(snd_pcm_t *pcm, int revents);
> pa_rtpoll_item* pa_alsa_build_pollfd(snd_pcm_t *pcm, pa_rtpoll *rtpoll);
>
> snd_pcm_sframes_t pa_alsa_safe_avail(snd_pcm_t *pcm, size_t hwbuf_size, const pa_sample_spec *ss);
> -int pa_alsa_safe_delay(snd_pcm_t *pcm, snd_pcm_sframes_t *delay, size_t hwbuf_size, const pa_sample_spec *ss, pa_bool_t capture);
> +int pa_alsa_safe_delay(snd_pcm_t *pcm, snd_pcm_status_t *status, snd_pcm_sframes_t *delay, size_t hwbuf_size, const pa_sample_spec *ss, pa_bool_t capture);
> int pa_alsa_safe_mmap_begin(snd_pcm_t *pcm, const snd_pcm_channel_area_t **areas, snd_pcm_uframes_t *offset, snd_pcm_uframes_t *frames, size_t hwbuf_size, const pa_sample_spec *ss);
>
> char *pa_alsa_get_driver_name(int card);
--
David Henningsson, Canonical Ltd.
https://launchpad.net/~diwic
