* [PATCH xawtv3 1/2] alsa: Fix not being able to get a larger latency on capture devices with small max period sizes
@ 2016-02-05 15:17 Hans de Goede
2016-02-05 15:17 ` [PATCH xawtv3 2/2] xawtv: Allow setting alsa_latency from ~/.xawtv Hans de Goede
0 siblings, 1 reply; 2+ messages in thread
From: Hans de Goede @ 2016-02-05 15:17 UTC (permalink / raw)
To: Linux Media Mailing List; +Cc: Hans de Goede
On some capture devices (e.g. bttv cards) the max period size is somewhat
small. Since we only use 2 perios on these devices we end up with only
allowing small latencies, which is a problem when e.g. using a usb codec
as output.
This commit fixes this by adjusting the amount of periods on the capture
side when this happens.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
common/alsa_stream.c | 22 +++++++++++++++++-----
1 file changed, 17 insertions(+), 5 deletions(-)
diff --git a/common/alsa_stream.c b/common/alsa_stream.c
index 3e33b5e..1165554 100644
--- a/common/alsa_stream.c
+++ b/common/alsa_stream.c
@@ -109,9 +109,10 @@ static void getparams_periods(snd_pcm_t *handle,
snd_pcm_hw_params_t *params,
unsigned int *usecs,
unsigned int *count,
- const char *id)
+ int allow_adjust, const char *id)
{
unsigned min = 0, max = 0;
+ unsigned desired = *usecs * *count;
snd_pcm_hw_params_get_periods_min(params, &min, 0);
snd_pcm_hw_params_get_periods_max(params, &max, 0);
@@ -137,6 +138,13 @@ static void getparams_periods(snd_pcm_t *handle,
if (*usecs > max)
*usecs = max;
}
+
+ /* If we deviate from the desired size by more then 20% adjust count */
+ if (allow_adjust && (((*usecs * *count) < (desired * 8 / 10)) ||
+ ((*usecs * *count) > (desired * 12 / 10)))) {
+ *count = (desired + *usecs / 2) / *usecs;
+ getparams_periods(handle, params, usecs, count, 0, id);
+ }
}
static int setparams_periods(snd_pcm_t *handle,
@@ -351,12 +359,16 @@ static int setparams(snd_pcm_t *phandle, snd_pcm_t *chandle,
/* Negotiate period parameters */
c_periodtime = latency * 1000 / c_periods;
- getparams_periods(chandle, c_hwparams, &c_periodtime, &c_periods, "capture");
+ getparams_periods(chandle, c_hwparams, &c_periodtime, &c_periods, 1, "capture");
p_periods = c_periods * 2;
p_periodtime = c_periodtime;
- getparams_periods(phandle, p_hwparams, &p_periodtime, &p_periods, "playback");
+ getparams_periods(phandle, p_hwparams, &p_periodtime, &p_periods, 0, "playback");
c_periods = p_periods / 2;
+ if (verbose)
+ fprintf(error_fp, "alsa: Capture %u periods of %u usecs, Playback %u periods of %u usecs\n",
+ c_periods, c_periodtime, p_periods, p_periodtime);
+
/*
* Some playback devices support a very limited periodtime range. If the user needs to
* use a higher latency to avoid overrun/underrun, use an alternate algorithm of incresing
@@ -365,10 +377,10 @@ static int setparams(snd_pcm_t *phandle, snd_pcm_t *chandle,
if (p_periodtime < c_periodtime) {
c_periodtime = p_periodtime;
c_periods = round (latency * 1000.0 / c_periodtime + 0.5);
- getparams_periods(chandle, c_hwparams, &c_periodtime, &c_periods, "capture");
+ getparams_periods(chandle, c_hwparams, &c_periodtime, &c_periods, 0, "capture");
p_periods = c_periods * 2;
p_periodtime = c_periodtime;
- getparams_periods(phandle, p_hwparams, &p_periodtime, &p_periods, "playback");
+ getparams_periods(phandle, p_hwparams, &p_periodtime, &p_periods, 0, "playback");
c_periods = p_periods / 2;
}
--
2.5.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH xawtv3 2/2] xawtv: Allow setting alsa_latency from ~/.xawtv
2016-02-05 15:17 [PATCH xawtv3 1/2] alsa: Fix not being able to get a larger latency on capture devices with small max period sizes Hans de Goede
@ 2016-02-05 15:17 ` Hans de Goede
0 siblings, 0 replies; 2+ messages in thread
From: Hans de Goede @ 2016-02-05 15:17 UTC (permalink / raw)
To: Linux Media Mailing List; +Cc: Hans de Goede
This avoids the need to always have to specify this on the cmdline on
systems which need a value different from the default.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
man/xawtvrc.5 | 5 +++++
x11/xt.c | 16 +++++++++++++---
2 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/man/xawtvrc.5 b/man/xawtvrc.5
index 136ceba..f1c3333 100644
--- a/man/xawtvrc.5
+++ b/man/xawtvrc.5
@@ -209,6 +209,11 @@ details.
.TP
.B filter = name
Enable the specified filter.
+.TP
+.B alsa_latency = time_in_ms
+This can be used to specify the latency for the ALSA digital sound loopback
+which xawtv does. The default is 30ms if you're getting sound dropouts on your
+system try increasing this setting.
.SS The [launch] section
You can start other programs from within xawtv. This is configured
with entries in the "[launch]" section:
diff --git a/x11/xt.c b/x11/xt.c
index 2065ff4..9affb4a 100644
--- a/x11/xt.c
+++ b/x11/xt.c
@@ -65,6 +65,10 @@
/*----------------------------------------------------------------------*/
+#define ALSA_LATENCY_DEFAULT 30
+#define STR(X) __STR(X)
+#define __STR(X) #X
+
XtAppContext app_context;
Widget app_shell, tv;
Widget on_shell;
@@ -167,7 +171,7 @@ XtResource args_desc[] = {
"alsa_latency",
XtCValue, XtRInt, sizeof(int),
XtOffset(struct ARGS*,alsa_latency),
- XtRString, "30"
+ XtRString, STR(ALSA_LATENCY_DEFAULT)
},{
/* Integer */
"debug",
@@ -1414,9 +1418,15 @@ static void x11_mute_notify(int val)
{
if (val)
alsa_thread_stop();
- else if (!alsa_thread_is_running())
+ else if (!alsa_thread_is_running()) {
+ if (args.readconfig && args.alsa_latency == ALSA_LATENCY_DEFAULT) {
+ int val = cfg_get_int("global", "alsa_latency");
+ if (val > 0)
+ args.alsa_latency = val;
+ }
alsa_thread_startup(alsa_out, alsa_cap, args.alsa_latency,
stderr, debug);
+ }
}
#endif
@@ -1698,7 +1708,7 @@ usage(void)
" -(no)alsa enable/disable alsa streaming. Default: enabled\n"
" -(no)alsa-cap manually specify an alsa capture interface\n"
" -(no)alsa-pb manually specify an alsa playback interface\n"
- " -alsa-latency manually specify an alsa latency in ms. Default: 30\n"
+ " -alsa-latency manually specify an alsa latency in ms. Default: " STR(ALSA_LATENCY_DEFAULT) "\n"
#endif
" -b -bpp n color depth of the display is n (n=24,32)\n"
" -o -outfile file filename base for snapshots\n"
--
2.5.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
end of thread, other threads:[~2016-02-05 15:17 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-02-05 15:17 [PATCH xawtv3 1/2] alsa: Fix not being able to get a larger latency on capture devices with small max period sizes Hans de Goede
2016-02-05 15:17 ` [PATCH xawtv3 2/2] xawtv: Allow setting alsa_latency from ~/.xawtv Hans de Goede
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).