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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;
}
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