Another try at sorting out the thorny question of timing.

1 files changed, 61 insertions, 0 deletions

diff --git a/src/lib/resampler.cc b/src/lib/resampler.cc
new file mode 100644
index 000000000..1235b9038
--- /dev/null
+++ b/src/lib/resampler.cc
@@ -0,0 +1,61 @@
+extern "C" {
+#include "libavutil/channel_layout.h"
+}	
+#include "resampler.h"
+#include "audio_buffers.h"
+#include "exceptions.h"
+
+#include "i18n.h"
+
+using boost::shared_ptr;
+
+Resampler::Resampler (int in, int out, int channels)
+	: _in_rate (in)
+	, _out_rate (out)
+	, _channels (channels)
+{
+	/* We will be using planar float data when we call the
+	   resampler.  As far as I can see, the audio channel
+	   layout is not necessary for our purposes; it seems
+	   only to be used get the number of channels and
+	   decide if rematrixing is needed.  It won't be, since
+	   input and output layouts are the same.
+	*/
+
+	_swr_context = swr_alloc_set_opts (
+		0,
+		av_get_default_channel_layout (_channels),
+		AV_SAMPLE_FMT_FLTP,
+		_out_rate,
+		av_get_default_channel_layout (_channels),
+		AV_SAMPLE_FMT_FLTP,
+		_in_rate,
+		0, 0
+		);
+	
+	swr_init (_swr_context);
+}
+
+Resampler::~Resampler ()
+{
+	swr_free (&_swr_context);
+}
+
+shared_ptr<const AudioBuffers>
+Resampler::run (shared_ptr<const AudioBuffers> in)
+{
+	/* Compute the resampled frames count and add 32 for luck */
+	int const max_resampled_frames = ceil ((double) in->frames() * _out_rate / _in_rate) + 32;
+	shared_ptr<AudioBuffers> resampled (new AudioBuffers (_channels, max_resampled_frames));
+
+	int const resampled_frames = swr_convert (
+		_swr_context, (uint8_t **) resampled->data(), max_resampled_frames, (uint8_t const **) in->data(), in->frames()
+		);
+	
+	if (resampled_frames < 0) {
+		throw EncodeError (_("could not run sample-rate converter"));
+	}
+	
+	resampled->set_frames (resampled_frames);
+	return resampled;
+}