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resampler: Add pa_resampler_prepare() and pa_resampler_get_delay() functions

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The pa_resampler_get_delay() function allows to retrieve the current resampler
delay in input samples for all supported resamplers. The return value is a double
to maintain precision when using variable rate resamplers. Because in many places
the delay is needed in usec, pa_resampler_get_delay_usec() was also supplied.

The speex resampler now skips leading zero samples to provide meaningful delay values.

In the next patch, the pa_resampler_prepare() function will be used to train the
resampler after a rewind. It takes data from a history memblockq and runs it through
the resampler. The output data is discarded.

To make this logic possible, the soxr resampler had to be converted to use variable
rate. The fixed rate version has a variable delay, therefore the logic above could
not be applied. Additionally, with fixed rate, the delay is larger than 150ms in
some situations, while with variable rate the delay is fixed and comparable to the
other resamplers.

Part-of: <https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/120>
This commit is contained in:
Georg Chini 2021-01-01 00:22:11 +01:00 • committed by PulseAudio Marge Bot
parent 1bfabd6512
commit 656179a8fe
6 changed files with 142 additions and 28 deletions
Download patch file Download diff file Expand all files Collapse all files

116
src/pulsecore/resampler.c
View file

@ -25,6 +25,7 @@
#include <math.h>
#include <pulse/xmalloc.h>
#include <pulse/timeval.h>
#include <pulsecore/log.h>
#include <pulsecore/macro.h>
#include <pulsecore/strbuf.h>
@ -164,9 +165,6 @@ static pa_resample_method_t fix_method(
}
/* Else fall through */
case PA_RESAMPLER_FFMPEG:
case PA_RESAMPLER_SOXR_MQ:
case PA_RESAMPLER_SOXR_HQ:
case PA_RESAMPLER_SOXR_VHQ:
if (flags & PA_RESAMPLER_VARIABLE_RATE) {
pa_log_info("Resampler '%s' cannot do variable rate, reverting to resampler 'auto'.", pa_resample_method_to_string(method));
method = PA_RESAMPLER_AUTO;
@ -350,6 +348,8 @@ pa_resampler* pa_resampler_new(
r->mempool = pool;
r->method = method;
r->flags = flags;
r->in_frames = 0;
r->out_frames = 0;
/* Fill sample specs */
r->i_ss = *a;
@ -480,6 +480,10 @@ void pa_resampler_set_input_rate(pa_resampler *r, uint32_t rate) {
if (r->i_ss.rate == rate)
return;
/* Recalculate delay counters */
r->in_frames = pa_resampler_get_delay(r, false);
r->out_frames = 0;
r->i_ss.rate = rate;
r->impl.update_rates(r);
@ -493,6 +497,10 @@ void pa_resampler_set_output_rate(pa_resampler *r, uint32_t rate) {
if (r->o_ss.rate == rate)
return;
/* Recalculate delay counters */
r->in_frames = pa_resampler_get_delay(r, false);
r->out_frames = 0;
r->o_ss.rate = rate;
r->impl.update_rates(r);
@ -626,20 +634,89 @@ void pa_resampler_reset(pa_resampler *r) {
pa_lfe_filter_reset(r->lfe_filter);
*r->have_leftover = false;
r->in_frames = 0;
r->out_frames = 0;
}
void pa_resampler_rewind(pa_resampler *r, size_t out_frames) {
/* This function runs amount bytes of data from the history queue through the
* resampler and discards the result. The history queue is unchanged after the
* call. This is used to preload a resampler after a reset. Returns the number
* of frames produced by the resampler. */
size_t pa_resampler_prepare(pa_resampler *r, pa_memblockq *history_queue, size_t amount) {
size_t history_bytes, max_block_size, out_size;
int64_t to_run;
pa_assert(r);
/* For now, we don't have any rewindable resamplers, so we just
reset the resampler instead (and hope that nobody hears the difference). */
if (r->impl.reset)
if (!history_queue || amount == 0)
return 0;
/* Rewind the LFE filter by the amount of history data. */
history_bytes = pa_resampler_result(r, amount);
if (r->lfe_filter)
pa_lfe_filter_rewind(r->lfe_filter, history_bytes);
pa_memblockq_rewind(history_queue, amount);
max_block_size = pa_resampler_max_block_size(r);
to_run = amount;
out_size = 0;
while (to_run > 0) {
pa_memchunk in_chunk, out_chunk;
size_t current;
current = PA_MIN(to_run, (int64_t) max_block_size);
/* Get data from memblockq */
if (pa_memblockq_peek_fixed_size(history_queue, current, &in_chunk) < 0) {
pa_log_warn("Could not read history data for resampler.");
/* Restore queue to original state and reset resampler */
pa_memblockq_drop(history_queue, to_run);
pa_resampler_reset(r);
return out_size;
}
/* Run the resampler */
pa_resampler_run(r, &in_chunk, &out_chunk);
/* Discard result */
if (out_chunk.length != 0) {
out_size += out_chunk.length;
pa_memblock_unref(out_chunk.memblock);
}
pa_memblock_unref(in_chunk.memblock);
pa_memblockq_drop(history_queue, current);
to_run -= current;
}
return out_size;
}
size_t pa_resampler_rewind(pa_resampler *r, size_t out_bytes, pa_memblockq *history_queue, size_t amount) {
pa_assert(r);
/* For now, we don't have any rewindable resamplers, so we just reset
* the resampler if we cannot rewind using pa_resampler_prepare(). */
if (r->impl.reset && !history_queue)
r->impl.reset(r);
if (r->lfe_filter)
pa_lfe_filter_rewind(r->lfe_filter, out_frames);
pa_lfe_filter_rewind(r->lfe_filter, out_bytes);
*r->have_leftover = false;
if (!history_queue) {
*r->have_leftover = false;
r->in_frames = 0;
r->out_frames = 0;
}
if (history_queue && amount > 0)
return pa_resampler_prepare(r, history_queue, amount);
return 0;
}
pa_resample_method_t pa_resampler_get_method(pa_resampler *r) {
@ -1509,6 +1586,7 @@ void pa_resampler_run(pa_resampler *r, const pa_memchunk *in, pa_memchunk *out)
pa_assert(in->length % r->i_fz == 0);
buf = (pa_memchunk*) in;
r->in_frames += buf->length / r->i_fz;
buf = convert_to_work_format(r, buf);
/* Try to save resampling effort: if we have more output channels than
@ -1527,6 +1605,7 @@ void pa_resampler_run(pa_resampler *r, const pa_memchunk *in, pa_memchunk *out)
if (buf->length) {
buf = convert_from_work_format(r, buf);
*out = *buf;
r->out_frames += buf->length / r->o_fz;
if (buf == in)
pa_memblock_ref(buf->memblock);
@ -1536,6 +1615,25 @@ void pa_resampler_run(pa_resampler *r, const pa_memchunk *in, pa_memchunk *out)
pa_memchunk_reset(out);
}
/* Get delay in input frames. Some resamplers may have negative delay. */
double pa_resampler_get_delay(pa_resampler *r, bool allow_negative) {
double frames;
frames = r->out_frames * r->i_ss.rate / r->o_ss.rate;
if (frames >= r->in_frames && !allow_negative)
return 0;
return r->in_frames - frames;
}
/* Get delay in usec */
pa_usec_t pa_resampler_get_delay_usec(pa_resampler *r) {
if (!r)
return 0;
return (pa_usec_t) (pa_resampler_get_delay(r, false) * PA_USEC_PER_SEC / r->i_ss.rate);
}
/*** copy (noop) implementation ***/
static int copy_init(pa_resampler *r) {