src/lib/audio_filter_graph.cc

   1 /*
   2     Copyright (C) 2015 Carl Hetherington <cth@carlh.net>
   3
   4     This file is part of DCP-o-matic.
   5
   6     DCP-o-matic is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     DCP-o-matic is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License
  17     along with DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.
  18
  19 */
  20
  21 #include "audio_filter_graph.h"
  22 #include "audio_buffers.h"
  23 #include "compose.hpp"
  24 extern "C" {
  25 #include <libavfilter/buffersink.h>
  26 #include <libavfilter/buffersrc.h>
  27 }
  28
  29 #include "i18n.h"
  30
  31 using std::string;
  32 using std::cout;
  33 using boost::shared_ptr;
  34
  35 AudioFilterGraph::AudioFilterGraph (int sample_rate, int channels)
  36         : _sample_rate (sample_rate)
  37         , _channels (channels)
  38 {
  39         /* FFmpeg doesn't know any channel layouts for any counts between 8 and 16,
  40            so we need to tell it we're using 16 channels if we are using more than 8.
  41         */
  42         if (_channels > 8) {
  43                 _channel_layout = av_get_default_channel_layout (16);
  44         } else {
  45                 _channel_layout = av_get_default_channel_layout (_channels);
  46         }
  47
  48         _in_frame = av_frame_alloc ();
  49 }
  50
  51 AudioFilterGraph::~AudioFilterGraph()
  52 {
  53         av_frame_free (&_in_frame);
  54 }
  55
  56 string
  57 AudioFilterGraph::src_parameters () const
  58 {
  59         SafeStringStream a;
  60
  61         char buffer[64];
  62         av_get_channel_layout_string (buffer, sizeof(buffer), 0, _channel_layout);
  63
  64         a << "time_base=1/1:sample_rate=" << _sample_rate << ":"
  65           << "sample_fmt=" << av_get_sample_fmt_name(AV_SAMPLE_FMT_FLTP) << ":"
  66           << "channel_layout=" << buffer;
  67
  68         return a.str ();
  69 }
  70
  71 void *
  72 AudioFilterGraph::sink_parameters () const
  73 {
  74         AVABufferSinkParams* sink_params = av_abuffersink_params_alloc ();
  75
  76         AVSampleFormat* sample_fmts = new AVSampleFormat[2];
  77         sample_fmts[0] = AV_SAMPLE_FMT_FLTP;
  78         sample_fmts[1] = AV_SAMPLE_FMT_NONE;
  79         sink_params->sample_fmts = sample_fmts;
  80
  81         int64_t* channel_layouts = new int64_t[2];
  82         channel_layouts[0] = _channel_layout;
  83         channel_layouts[1] = -1;
  84         sink_params->channel_layouts = channel_layouts;
  85
  86         sink_params->sample_rates = new int[2];
  87         sink_params->sample_rates[0] = _sample_rate;
  88         sink_params->sample_rates[1] = -1;
  89
  90         return sink_params;
  91 }
  92
  93 string
  94 AudioFilterGraph::src_name () const
  95 {
  96         return "abuffer";
  97 }
  98
  99 string
 100 AudioFilterGraph::sink_name () const
 101 {
 102         return "abuffersink";
 103 }
 104
 105 void
 106 AudioFilterGraph::process (shared_ptr<const AudioBuffers> buffers)
 107 {
 108         int const process_channels = av_get_channel_layout_nb_channels (_channel_layout);
 109         DCPOMATIC_ASSERT (process_channels >= buffers->channels());
 110
 111         if (buffers->channels() < process_channels) {
 112                 /* We are processing more data than we actually have (see the hack in
 113                    the constructor) so we need to create new buffers with some extra
 114                    silent channels.
 115                 */
 116                 shared_ptr<AudioBuffers> extended_buffers (new AudioBuffers (process_channels, buffers->frames()));
 117                 for (int i = 0; i < buffers->channels(); ++i) {
 118                         extended_buffers->copy_channel_from (buffers.get(), i, i);
 119                 }
 120                 for (int i = buffers->channels(); i < process_channels; ++i) {
 121                         extended_buffers->make_silent (i);
 122                 }
 123
 124                 buffers = extended_buffers;
 125         }
 126
 127         _in_frame->extended_data = new uint8_t*[process_channels];
 128         for (int i = 0; i < buffers->channels(); ++i) {
 129                 if (i < AV_NUM_DATA_POINTERS) {
 130                         _in_frame->data[i] = reinterpret_cast<uint8_t*> (buffers->data(i));
 131                 }
 132                 _in_frame->extended_data[i] = reinterpret_cast<uint8_t*> (buffers->data(i));
 133         }
 134
 135         _in_frame->nb_samples = buffers->frames ();
 136         _in_frame->format = AV_SAMPLE_FMT_FLTP;
 137         _in_frame->sample_rate = _sample_rate;
 138         _in_frame->channel_layout = _channel_layout;
 139         _in_frame->channels = process_channels;
 140
 141         int r = av_buffersrc_write_frame (_buffer_src_context, _in_frame);
 142
 143         delete[] _in_frame->extended_data;
 144         /* Reset extended_data to its original value so that av_frame_free
 145            does not try to free it.
 146         */
 147         _in_frame->extended_data = _in_frame->data;
 148
 149         if (r < 0) {
 150                 char buffer[256];
 151                 av_strerror (r, buffer, sizeof(buffer));
 152                 throw DecodeError (String::compose (N_("could not push buffer into filter chain (%1)"), buffer));
 153         }
 154
 155         while (true) {
 156                 if (av_buffersink_get_frame (_buffer_sink_context, _frame) < 0) {
 157                         break;
 158                 }
 159
 160                 /* We don't extract audio data here, since the only use of this class
 161                    is for ebur128.
 162                 */
 163
 164                 av_frame_unref (_frame);
 165         }
 166 }