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audiofxbasefirfilter: Optimize time-domain convolution

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Remove some redundant calculations, move comparisions out of
inner loops, etc.

This makes the convolution about 3 (!) times faster but
processing time is of course still proportional to the
filter size.
This commit is contained in:
Sebastian Dröge 2009-11-26 15:17:27 +01:00
parent c5f955a3b6
commit 43576fb0cf
1 changed files with 28 additions and 15 deletions
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43
gst/audiofx/audiofxbasefirfilter.c
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@ -149,37 +149,50 @@ process_##width (GstAudioFXBaseFIRFilter * self, const g##ctype * src, g##ctype
gint i, j, k, l; \
gint channels = GST_AUDIO_FILTER_CAST (self)->format.channels; \
gint res_start; \
gint from_input; \
gint off; \
gdouble *buffer = self->buffer; \
gdouble *kernel = self->kernel; \
guint buffer_length = self->buffer_length; \
\
/* convolution */ \
for (i = 0; i < input_samples; i++) { \
dst[i] = 0.0; \
k = i % channels; \
l = i / channels; \
for (j = 0; j < kernel_length; j++) \
if (l < j) \
dst[i] += \
self->buffer[(kernel_length + l - j) * channels + \
k] * self->kernel[j]; \
else \
dst[i] += src[(l - j) * channels + k] * self->kernel[j]; \
from_input = MIN (l, kernel_length-1); \
off = l * channels + k; \
for (j = 0; j <= from_input; j++) { \
dst[i] += src[off] * kernel[j]; \
off -= channels; \
} \
/* j == from_input && off == (l - j) * channels + k */ \
off += kernel_length * channels; \
for (; j < kernel_length; j++) { \
dst[i] += buffer[off] * kernel[j]; \
off -= channels; \
} \
} \
\
/* copy the tail of the current input buffer to the residue, while \
* keeping parts of the residue if the input buffer is smaller than \
* the kernel length */ \
if (input_samples < kernel_length * channels) \
res_start = kernel_length * channels - input_samples; \
/* from now on take kernel length as length over all channels */ \
kernel_length *= channels; \
if (input_samples < kernel_length) \
res_start = kernel_length - input_samples; \
else \
res_start = 0; \
\
for (i = 0; i < res_start; i++) \
self->buffer[i] = self->buffer[i + input_samples]; \
for (i = res_start; i < kernel_length * channels; i++) \
self->buffer[i] = src[input_samples - kernel_length * channels + i]; \
buffer[i] = buffer[i + input_samples]; \
/* i == res_start */ \
for (; i < kernel_length; i++) \
buffer[i] = src[input_samples - kernel_length + i]; \
\
self->buffer_fill += kernel_length * channels - res_start; \
if (self->buffer_fill > kernel_length * channels) \
self->buffer_fill = kernel_length * channels; \
self->buffer_fill += kernel_length - res_start; \
if (self->buffer_fill > kernel_length) \
self->buffer_fill = kernel_length; \
}
DEFINE_PROCESS_FUNC (32, float);