src/lib/audio_filter_graph.cc

   1 /*
   2     Copyright (C) 2015 Carl Hetherington <cth@carlh.net>
   3
   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.
   8
   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.
  13
  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.
  17
  18 */
  19
  20 #include "audio_filter_graph.h"
  21 #include "audio_buffers.h"
  22 #include "compose.hpp"
  23 extern "C" {
  24 #include <libavfilter/buffersink.h>
  25 #include <libavfilter/buffersrc.h>
  26 }
  27
  28 #include "i18n.h"
  29
  30 using std::string;
  31 using std::cout;
  32 using boost::shared_ptr;
  33
  34 AudioFilterGraph::AudioFilterGraph (int sample_rate, int channels)
  35         : _sample_rate (sample_rate)
  36         , _channels (channels)
  37 {
  38         /* FFmpeg doesn't know any channel layouts for any counts between 8 and 16,
  39            so we need to tell it we're using 16 channels if we are using more than 8.
  40         */
  41         if (_channels > 8) {
  42                 _channel_layout = av_get_default_channel_layout (16);
  43         } else {
  44                 _channel_layout = av_get_default_channel_layout (_channels);
  45         }
  46
  47         _in_frame = av_frame_alloc ();
  48 }
  49
  50 AudioFilterGraph::~AudioFilterGraph()
  51 {
  52         av_frame_free (&_in_frame);
  53 }
  54
  55 string
  56 AudioFilterGraph::src_parameters () const
  57 {
  58         SafeStringStream a;
  59
  60         char buffer[64];
  61         av_get_channel_layout_string (buffer, sizeof(buffer), 0, _channel_layout);
  62
  63         a << "time_base=1/1:sample_rate=" << _sample_rate << ":"
  64           << "sample_fmt=" << av_get_sample_fmt_name(AV_SAMPLE_FMT_FLTP) << ":"
  65           << "channel_layout=" << buffer;
  66
  67         return a.str ();
  68 }
  69
  70 void *
  71 AudioFilterGraph::sink_parameters () const
  72 {
  73         AVABufferSinkParams* sink_params = av_abuffersink_params_alloc ();
  74
  75         AVSampleFormat* sample_fmts = new AVSampleFormat[2];
  76         sample_fmts[0] = AV_SAMPLE_FMT_FLTP;
  77         sample_fmts[1] = AV_SAMPLE_FMT_NONE;
  78         sink_params->sample_fmts = sample_fmts;
  79
  80         int64_t* channel_layouts = new int64_t[2];
  81         channel_layouts[0] = _channel_layout;
  82         channel_layouts[1] = -1;
  83         sink_params->channel_layouts = channel_layouts;
  84
  85         sink_params->sample_rates = new int[2];
  86         sink_params->sample_rates[0] = _sample_rate;
  87         sink_params->sample_rates[1] = -1;
  88
  89         return sink_params;
  90 }
  91
  92 string
  93 AudioFilterGraph::src_name () const
  94 {
  95         return "abuffer";
  96 }
  97
  98 string
  99 AudioFilterGraph::sink_name () const
 100 {
 101         return "abuffersink";
 102 }
 103
 104 void
 105 AudioFilterGraph::process (shared_ptr<const AudioBuffers> buffers)
 106 {
 107         int const process_channels = av_get_channel_layout_nb_channels (_channel_layout);
 108         DCPOMATIC_ASSERT (process_channels >= buffers->channels());
 109
 110         if (buffers->channels() < process_channels) {
 111                 /* We are processing more data than we actually have (see the hack in
 112                    the constructor) so we need to create new buffers with some extra
 113                    silent channels.
 114                 */
 115                 shared_ptr<AudioBuffers> extended_buffers (new AudioBuffers (process_channels, buffers->frames()));
 116                 for (int i = 0; i < buffers->channels(); ++i) {
 117                         extended_buffers->copy_channel_from (buffers.get(), i, i);
 118                 }
 119                 for (int i = buffers->channels(); i < process_channels; ++i) {
 120                         extended_buffers->make_silent (i);
 121                 }
 122
 123                 buffers = extended_buffers;
 124         }
 125
 126         _in_frame->extended_data = new uint8_t*[process_channels];
 127         for (int i = 0; i < buffers->channels(); ++i) {
 128                 if (i < AV_NUM_DATA_POINTERS) {
 129                         _in_frame->data[i] = reinterpret_cast<uint8_t*> (buffers->data(i));
 130                 }
 131                 _in_frame->extended_data[i] = reinterpret_cast<uint8_t*> (buffers->data(i));
 132         }
 133
 134         _in_frame->nb_samples = buffers->frames ();
 135         _in_frame->format = AV_SAMPLE_FMT_FLTP;
 136         _in_frame->sample_rate = _sample_rate;
 137         _in_frame->channel_layout = _channel_layout;
 138         _in_frame->channels = process_channels;
 139
 140         int r = av_buffersrc_write_frame (_buffer_src_context, _in_frame);
 141
 142         delete[] _in_frame->extended_data;
 143         /* Reset extended_data to its original value so that av_frame_free
 144            does not try to free it.
 145         */
 146         _in_frame->extended_data = _in_frame->data;
 147
 148         if (r < 0) {
 149                 char buffer[256];
 150                 av_strerror (r, buffer, sizeof(buffer));
 151                 throw DecodeError (String::compose (N_("could not push buffer into filter chain (%1)"), buffer));
 152         }
 153
 154         while (true) {
 155                 if (av_buffersink_get_frame (_buffer_sink_context, _frame) < 0) {
 156                         break;
 157                 }
 158
 159                 /* We don't extract audio data here, since the only use of this class
 160                    is for ebur128.
 161                 */
 162
 163                 av_frame_unref (_frame);
 164         }
 165 }