You can use the default-sample-rate/alternate-sample-rate config values
as minimal sample rates.
So if you input a 8kHz audio stream, you resample it to 48kHz or 44.1kHz
rather than let it to go 8Khz.
I attached my patches.
They just remove the limitation that the desired sample rate should be
either default-sample-rate or alternate-sample-rate when the sink is
opened.
This was just a quick hack as I don't know pulseaudio source code at
all.
Feel free to discuss or modify them :)
The resulting behavior is the following:
New audio stream 88200Hz -> sink & source at 88200Hz
Adding a stream at 441000Hz -> sink & source don't change their sample
rate (still 88200Hz so). The additionnal stream is thus resampled to
88200Hz
Shutdown sink, New audio stream at 441000Hz -> sink & source at 44100Hz
Shutdown sink, New audio stream at 8000Hz -> sink & source at 44100Hz
because there seems to be a lower limit (maybe 8Khz is not in the
supported rates of the sound card :D ).
I can add to the patch a software limitation so the desired sample rate
can't be below default-sample-rate value for example.
Best regards,
Le dimanche 27 novembre 2016 à 17:16 +0200, Tanu Kaskinen a écrit :
> The dynamic rate switching was added to deal specifically with the most
> common case: switching between 44100 Hz and 48000 Hz. It's not that
> supporting a more flexible policy is necessarily undesirable, it's just
> that nobody has been interested enough to provide patches.
>
> One reason why we don't simply try to switch to whatever rate streams
> happen to have is that we don't want to end up in a situation where one
> stream causes the sink to run at 8000 Hz and then an overlapping higher
> quality stream appears and suffers from the very low sink rate.
>
> So, if we relax the rate restrictions, we need to add at least a limit
> for how low rates we accept. I don't remember if there were any other
> considerations when this feature was discussed. If you provide patches
> for improving the rate switching policy, at this point I don't see any
> reason why such feature would be rejected.
>
--- /home/erwan/apps/pulseaudio/original/pulseaudio-7.1/src/pulsecore/sink.c 2015-10-19 05:16:31.000000000 +0200
+++ /home/erwan/apps/pulseaudio/pulseaudio-7.1/src/pulsecore/sink.c 2016-11-27 22:23:22.369700147 +0100
@@ -1385,24 +1385,15 @@
int pa_sink_update_rate(pa_sink *s, uint32_t rate, bool passthrough) {
int ret = -1;
uint32_t desired_rate = rate;
- uint32_t default_rate = s->default_sample_rate;
- uint32_t alternate_rate = s->alternate_sample_rate;
uint32_t idx;
pa_sink_input *i;
- bool default_rate_is_usable = false;
- bool alternate_rate_is_usable = false;
- if (rate == s->sample_spec.rate)
+ if (desired_rate == s->sample_spec.rate)
return 0;
if (!s->update_rate)
return -1;
- if (PA_UNLIKELY(default_rate == alternate_rate && !passthrough)) {
- pa_log_debug("Default and alternate sample rates are the same, so there is no point in switching.");
- return -1;
- }
-
if (PA_SINK_IS_RUNNING(s->state)) {
pa_log_info("Cannot update rate, SINK_IS_RUNNING, will keep using %u Hz",
s->sample_spec.rate);
@@ -1419,25 +1410,6 @@
if (PA_UNLIKELY(!pa_sample_rate_valid(desired_rate)))
return -1;
- if (!passthrough && default_rate != desired_rate && alternate_rate != desired_rate) {
- if (default_rate % 11025 == 0 && desired_rate % 11025 == 0)
- default_rate_is_usable = true;
- if (default_rate % 4000 == 0 && desired_rate % 4000 == 0)
- default_rate_is_usable = true;
- if (alternate_rate && alternate_rate % 11025 == 0 && desired_rate % 11025 == 0)
- alternate_rate_is_usable = true;
- if (alternate_rate && alternate_rate % 4000 == 0 && desired_rate % 4000 == 0)
- alternate_rate_is_usable = true;
-
- if (alternate_rate_is_usable && !default_rate_is_usable)
- desired_rate = alternate_rate;
- else
- desired_rate = default_rate;
- }
-
- if (desired_rate == s->sample_spec.rate)
- return -1;
-
if (!passthrough && pa_sink_used_by(s) > 0)
return -1;
--- /home/erwan/apps/pulseaudio/original/pulseaudio-7.1/src/pulsecore/source.c 2015-09-25 14:09:43.000000000 +0200
+++ /home/erwan/apps/pulseaudio/pulseaudio-7.1/src/pulsecore/source.c 2016-11-27 22:11:26.000000000 +0100
@@ -975,22 +975,13 @@
int pa_source_update_rate(pa_source *s, uint32_t rate, bool passthrough) {
int ret;
uint32_t desired_rate = rate;
- uint32_t default_rate = s->default_sample_rate;
- uint32_t alternate_rate = s->alternate_sample_rate;
- bool default_rate_is_usable = false;
- bool alternate_rate_is_usable = false;
- if (rate == s->sample_spec.rate)
+ if (desired_rate == s->sample_spec.rate)
return 0;
if (!s->update_rate && !s->monitor_of)
return -1;
- if (PA_UNLIKELY(default_rate == alternate_rate && !passthrough)) {
- pa_log_debug("Default and alternate sample rates are the same, so there is no point in switching.");
- return -1;
- }
-
if (PA_SOURCE_IS_RUNNING(s->state)) {
pa_log_info("Cannot update rate, SOURCE_IS_RUNNING, will keep using %u Hz",
s->sample_spec.rate);
@@ -1007,25 +998,6 @@
if (PA_UNLIKELY(!pa_sample_rate_valid(desired_rate)))
return -1;
- if (!passthrough && default_rate != desired_rate && alternate_rate != desired_rate) {
- if (default_rate % 11025 == 0 && desired_rate % 11025 == 0)
- default_rate_is_usable = true;
- if (default_rate % 4000 == 0 && desired_rate % 4000 == 0)
- default_rate_is_usable = true;
- if (alternate_rate && alternate_rate % 11025 == 0 && desired_rate % 11025 == 0)
- alternate_rate_is_usable = true;
- if (alternate_rate && alternate_rate % 4000 == 0 && desired_rate % 4000 == 0)
- alternate_rate_is_usable = true;
-
- if (alternate_rate_is_usable && !default_rate_is_usable)
- desired_rate = alternate_rate;
- else
- desired_rate = default_rate;
- }
-
- if (desired_rate == s->sample_spec.rate)
- return -1;
-
if (!passthrough && pa_source_used_by(s) > 0)
return -1;
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