2 Copyright (C) 2013 Carl Hetherington <cth@carlh.net>
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 #include "libavutil/channel_layout.h"
23 #include "resampler.h"
24 #include "audio_buffers.h"
25 #include "exceptions.h"
32 using boost::shared_ptr;
34 Resampler::Resampler (int in, int out, int channels)
37 , _channels (channels)
39 /* We will be using planar float data when we call the
40 resampler. As far as I can see, the audio channel
41 layout is not necessary for our purposes; it seems
42 only to be used get the number of channels and
43 decide if rematrixing is needed. It won't be, since
44 input and output layouts are the same.
47 _swr_context = swr_alloc_set_opts (
49 av_get_default_channel_layout (_channels),
52 av_get_default_channel_layout (_channels),
58 swr_init (_swr_context);
61 Resampler::~Resampler ()
63 swr_free (&_swr_context);
66 pair<shared_ptr<const AudioBuffers>, AudioContent::Frame>
67 Resampler::run (shared_ptr<const AudioBuffers> in, AudioContent::Frame frame)
69 AudioContent::Frame const resamp_time = swr_next_pts (_swr_context, frame * _out_rate) / _in_rate;
71 /* Compute the resampled frames count and add 32 for luck */
72 int const max_resampled_frames = ceil ((double) in->frames() * _out_rate / _in_rate) + 32;
73 shared_ptr<AudioBuffers> resampled (new AudioBuffers (_channels, max_resampled_frames));
75 int const resampled_frames = swr_convert (
76 _swr_context, (uint8_t **) resampled->data(), max_resampled_frames, (uint8_t const **) in->data(), in->frames()
79 if (resampled_frames < 0) {
80 throw EncodeError (_("could not run sample-rate converter"));
83 resampled->set_frames (resampled_frames);
84 return make_pair (resampled, resamp_time);
87 shared_ptr<const AudioBuffers>
90 shared_ptr<AudioBuffers> out (new AudioBuffers (_channels, 0));
92 int64_t const pass_size = 256;
93 shared_ptr<AudioBuffers> pass (new AudioBuffers (_channels, 256));
96 int const frames = swr_convert (_swr_context, (uint8_t **) pass->data(), pass_size, 0, 0);
99 throw EncodeError (_("could not run sample-rate converter"));
106 out->ensure_size (out_offset + frames);
107 out->copy_from (pass.get(), frames, 0, out_offset);
108 out_offset += frames;
109 out->set_frames (out_offset);