While this is quite fast on x86 (order of a few microseconds), the
computation can take a few milliseconds on ARM (measured at 1.9ms (32000
-> 48000) and 3.3ms (32000 -> 44100) on a Cortex A53).
Let's precompute some common rates so that we can avoid this overhead on
each stream (or any other audioconvert) instantiation. The approach
taken here is to write a little program to create the resampler
instance, and run that on the host at compile-time to generate some
common rate conversions.
The rate we get from dlls can have a subsample precision. However,
the check for using process_copy is in sample precision. This means
that an adaptive stream will oscillate rather then lock into the
exact rate.
uint32_t i;
for (i = 0; i < SPA_N_ELEMENTS(some_array); i++)
.. stuff with some_array[i].foo ...
becomes:
SPA_FOR_EACH_ELEMENT_VAR(some_array, p)
.. stuff with p->foo ..
Add a resampler option to prefill the resampler with 0. This then
results in the resampler always outputing and consuming the same
amount of data instead of a short buffer in the beginning.
By: Kevin Yin
R->A calculation removed: it wasn't valid anyway. No behavior change.
Placed existing A in there directly.
cosh window -> strangely tweaked exp window: remove the discontinuity
at the border, which is wrong for a window function. If A changes in the
future, this window will be better. With the current A, you will not be
able to tell the difference on any graph. (Of course, it's not a cosh
window anymore.)
Fixes#2574
Move the noise setting in the dither struct so that it can be
handled separately.
Setup dither separately.
Set used cpu_flags in structures after setup.
Don't use the previously skipped sample to calculate the remaining
amount of samples or else we remove one sample too much in some cases
and cause distortion, mostly when downsampling.
Fixes#1646
That was found by GCC fanalyze pass. Fixes warning:
../spa/plugins/audioconvert/resample-native.c: In function ‘resample_native_init’:
../spa/plugins/audioconvert/resample-native.c:385:9: warning: dereference of NULL ‘0B’ [CWE-476] [-Wanalyzer-null-dereference]
385 | spa_log_debug(r->log, "native %p: q:%d in:%d out:%d n_taps:%d n_phases:%d features:%08x:%08x",
SPA_MEMBER is misleading, all we're doing here is pointer+offset and a
type-casting the result. Rename to SPA_PTROFF which is more expressive (and
has the same number of characters so we don't need to re-indent).
Instead of requiring the upstream node to resubmit the delayed
samples, keep the samples ourselves. The benefit is probably too
small to measure but it simplifies things a lot.
Takes into account the number of skipped samples when deciding whether
we should copy the remaining samples in the history or not.
Fixes dropping audio issue when resampling from high frequencies
such as 48KHz to low requencies such as 8KHz.
