From 537f430c993ee5d83a8c58e8121b457c904d6cdb Mon Sep 17 00:00:00 2001 From: Peter Meerwald Date: Mon, 2 Dec 2013 17:27:01 +0100 Subject: [PATCH] resampler: Resample first followed by remapping if have more out channels than in channels MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Reintroduces a cleaned-up version of commit 30ce3a14e5ae1cd316a18bec95b831c07ac57a1a which was reverted by 1ce71cbd8206d1be59ac62274ad83cdbe693a96a; for more information see http://thread.gmane.org/gmane.comp.audio.pulseaudio.general/17479/focus=17487 The patch intends to reduce computational load when resampling AND remapping. The PA resampler performs the following steps: sample format conversion -> remapping -> resampling -> sample format conversion In case the number of output channels is higher than the number of input channels, the resampler has to be run more often than necessary. E.g. in case of mono to 4-channel remapping, the resampler runs on 4 channels separately. To ímprove this, the PA resampler pipeline is made adaptive: if out-channels <= in-channels: sample format conversion -> remapping -> resampling -> sample format conversion if out-channels > in-channels: sample format conversion -> resampling -> remapping -> sample format conversion Signed-off-by: Peter Meerwald --- src/pulsecore/resampler.c | 44 ++++++++++++++++++++++++++++----------- 1 file changed, 32 insertions(+), 12 deletions(-) diff --git a/src/pulsecore/resampler.c b/src/pulsecore/resampler.c index db65ceaad..38389f381 100644 --- a/src/pulsecore/resampler.c +++ b/src/pulsecore/resampler.c @@ -398,12 +398,7 @@ pa_resampler* pa_resampler_new( calc_map_table(r); - pa_log_info("Using resampler '%s'", pa_resample_method_to_string(method)); - r->work_format = pa_resampler_choose_work_format(method, a->format, b->format, r->map_required); - - pa_log_info("Using %s as working format.", pa_sample_format_to_string(r->work_format)); - r->w_sz = pa_sample_size_of_format(r->work_format); if (r->i_ss.format != r->work_format) { @@ -428,14 +423,31 @@ pa_resampler* pa_resampler_new( } } - /* leftover buffer is the buffer before the resampling stage */ - r->leftover_buf = &r->remap_buf; - r->leftover_buf_size = &r->remap_buf_size; - r->have_leftover = &r->leftover_in_remap; + if (r->o_ss.channels <= r->i_ss.channels) { + /* pipeline is: format conv. -> remap -> resample -> format conv. */ + r->work_channels = r->o_ss.channels; - r->work_channels = r->o_ss.channels; + /* leftover buffer is remap output buffer (before resampling) */ + r->leftover_buf = &r->remap_buf; + r->leftover_buf_size = &r->remap_buf_size; + r->have_leftover = &r->leftover_in_remap; + } else { + /* pipeline is: format conv. -> resample -> remap -> format conv. */ + r->work_channels = r->i_ss.channels; + + /* leftover buffer is to_work output buffer (before resampling) */ + r->leftover_buf = &r->to_work_format_buf; + r->leftover_buf_size = &r->to_work_format_buf_size; + r->have_leftover = &r->leftover_in_to_work; + } r->w_fz = pa_sample_size_of_format(r->work_format) * r->work_channels; + pa_log_debug("Resampler:"); + pa_log_debug(" rate %d -> %d (method %s)", a->rate, b->rate, pa_resample_method_to_string(r->method)); + pa_log_debug(" format %s -> %s (intermediate %s)", pa_sample_format_to_string(a->format), + pa_sample_format_to_string(b->format), pa_sample_format_to_string(r->work_format)); + pa_log_debug(" channels %d -> %d (resampling %d)", a->channels, b->channels, r->work_channels); + /* initialize implementation */ if (init_table[method](r) < 0) goto fail; @@ -1348,8 +1360,16 @@ void pa_resampler_run(pa_resampler *r, const pa_memchunk *in, pa_memchunk *out) buf = (pa_memchunk*) in; buf = convert_to_work_format(r, buf); - buf = remap_channels(r, buf); - buf = resample(r, buf); + + /* Try to save resampling effort: if we have more output channels than + * input channels, do resampling first, then remapping. */ + if (r->o_ss.channels <= r->i_ss.channels) { + buf = remap_channels(r, buf); + buf = resample(r, buf); + } else { + buf = resample(r, buf); + buf = remap_channels(r, buf); + } if (buf->length) { buf = convert_from_work_format(r, buf);