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, int64_t channel_layout)
  35         : _sample_rate (sample_rate)
  36         , _channel_layout (channel_layout)
  37 {
  38         _in_frame = av_frame_alloc ();
  39 }
  40
  41 AudioFilterGraph::~AudioFilterGraph()
  42 {
  43         av_frame_free (&_in_frame);
  44 }
  45
  46 string
  47 AudioFilterGraph::src_parameters () const
  48 {
  49         SafeStringStream a;
  50
  51         char buffer[64];
  52         av_get_channel_layout_string (buffer, sizeof(buffer), 0, _channel_layout);
  53
  54         a << "time_base=1/1:sample_rate=" << _sample_rate << ":"
  55           << "sample_fmt=" << av_get_sample_fmt_name(AV_SAMPLE_FMT_FLTP) << ":"
  56           << "channel_layout=" << buffer;
  57
  58         return a.str ();
  59 }
  60
  61 void *
  62 AudioFilterGraph::sink_parameters () const
  63 {
  64         AVABufferSinkParams* sink_params = av_abuffersink_params_alloc ();
  65
  66         AVSampleFormat* sample_fmts = new AVSampleFormat[2];
  67         sample_fmts[0] = AV_SAMPLE_FMT_FLTP;
  68         sample_fmts[1] = AV_SAMPLE_FMT_NONE;
  69         sink_params->sample_fmts = sample_fmts;
  70
  71         int64_t* channel_layouts = new int64_t[2];
  72         channel_layouts[0] = _channel_layout;
  73         channel_layouts[1] = -1;
  74         sink_params->channel_layouts = channel_layouts;
  75
  76         sink_params->sample_rates = new int[2];
  77         sink_params->sample_rates[0] = _sample_rate;
  78         sink_params->sample_rates[1] = -1;
  79
  80         return sink_params;
  81 }
  82
  83 string
  84 AudioFilterGraph::src_name () const
  85 {
  86         return "abuffer";
  87 }
  88
  89 string
  90 AudioFilterGraph::sink_name () const
  91 {
  92         return "abuffersink";
  93 }
  94
  95 void
  96 AudioFilterGraph::process (shared_ptr<const AudioBuffers> buffers)
  97 {
  98         _in_frame->extended_data = new uint8_t*[buffers->channels()];
  99         for (int i = 0; i < buffers->channels(); ++i) {
 100                 if (i < AV_NUM_DATA_POINTERS) {
 101                         _in_frame->data[i] = reinterpret_cast<uint8_t*> (buffers->data(i));
 102                 }
 103                 _in_frame->extended_data[i] = reinterpret_cast<uint8_t*> (buffers->data(i));
 104         }
 105
 106         _in_frame->nb_samples = buffers->frames ();
 107         _in_frame->format = AV_SAMPLE_FMT_FLTP;
 108         _in_frame->sample_rate = _sample_rate;
 109         _in_frame->channel_layout = _channel_layout;
 110         _in_frame->channels = av_get_channel_layout_nb_channels (_channel_layout);
 111
 112         int r = av_buffersrc_write_frame (_buffer_src_context, _in_frame);
 113
 114         delete[] _in_frame->extended_data;
 115         /* Reset extended_data to its original value so that av_frame_free
 116            does not try to free it.
 117         */
 118         _in_frame->extended_data = _in_frame->data;
 119
 120         if (r < 0) {
 121                 char buffer[256];
 122                 av_strerror (r, buffer, sizeof(buffer));
 123                 throw DecodeError (String::compose (N_("could not push buffer into filter chain (%1)"), buffer));
 124         }
 125
 126         while (true) {
 127                 if (av_buffersink_get_frame (_buffer_sink_context, _frame) < 0) {
 128                         break;
 129                 }
 130
 131                 /* We don't extract audio data here, since the only use of this class
 132                    is for ebur128.
 133                 */
 134
 135                 av_frame_unref (_frame);
 136         }
 137 }