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
  22 #include "audio_buffers.h"
  23 #include "audio_filter_graph.h"
  24 #include "compose.hpp"
  25 extern "C" {
  26 #include <libavfilter/buffersink.h>
  27 #include <libavfilter/buffersrc.h>
  28 #include <libavutil/channel_layout.h>
  29 #include <libavutil/opt.h>
  30 }
  31 #include <iostream>
  32
  33 #include "i18n.h"
  34
  35
  36 using std::cout;
  37 using std::make_shared;
  38 using std::shared_ptr;
  39 using std::string;
  40
  41
  42 AudioFilterGraph::AudioFilterGraph (int sample_rate, int channels)
  43         : _sample_rate (sample_rate)
  44         , _channels (channels)
  45 {
  46         /* FFmpeg doesn't know any channel layouts for any counts between 8 and 16,
  47            so we need to tell it we're using 16 channels if we are using more than 8.
  48         */
  49         av_channel_layout_default(&_channel_layout, _channels > 8 ? 16 : _channels);
  50
  51         _in_frame = av_frame_alloc ();
  52 }
  53
  54 AudioFilterGraph::~AudioFilterGraph()
  55 {
  56         av_frame_free (&_in_frame);
  57 }
  58
  59 string
  60 AudioFilterGraph::src_parameters () const
  61 {
  62         char layout[64];
  63         av_channel_layout_describe(&_channel_layout, layout, sizeof(layout));
  64
  65         char buffer[256];
  66         snprintf (
  67                 buffer, sizeof(buffer), "time_base=1/1:sample_rate=%d:sample_fmt=%s:channel_layout=%s",
  68                 _sample_rate, av_get_sample_fmt_name(AV_SAMPLE_FMT_FLTP), layout
  69                 );
  70
  71         return buffer;
  72 }
  73
  74
  75 void
  76 AudioFilterGraph::set_parameters (AVFilterContext* context) const
  77 {
  78         AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_FLTP, AV_SAMPLE_FMT_NONE };
  79         int r = av_opt_set_int_list (context, "sample_fmts", sample_fmts, AV_SAMPLE_FMT_NONE, AV_OPT_SEARCH_CHILDREN);
  80         DCPOMATIC_ASSERT (r >= 0);
  81
  82         char ch_layout[64];
  83         av_channel_layout_describe(&_channel_layout, ch_layout, sizeof(ch_layout));
  84         r = av_opt_set(context, "ch_layouts", ch_layout, AV_OPT_SEARCH_CHILDREN);
  85         DCPOMATIC_ASSERT (r >= 0);
  86
  87         int sample_rates[] = { _sample_rate, -1 };
  88         r = av_opt_set_int_list (context, "sample_rates", sample_rates, -1, AV_OPT_SEARCH_CHILDREN);
  89         DCPOMATIC_ASSERT (r >= 0);
  90 }
  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<AudioBuffers> buffers)
 107 {
 108         DCPOMATIC_ASSERT (buffers->frames() > 0);
 109         int const process_channels = _channel_layout.nb_channels;
 110         DCPOMATIC_ASSERT (process_channels >= buffers->channels());
 111
 112         if (buffers->channels() < process_channels) {
 113                 /* We are processing more data than we actually have (see the hack in
 114                    the constructor) so we need to create new buffers with some extra
 115                    silent channels.
 116                 */
 117                 auto extended_buffers = make_shared<AudioBuffers>(process_channels, buffers->frames());
 118                 for (int i = 0; i < buffers->channels(); ++i) {
 119                         extended_buffers->copy_channel_from (buffers.get(), i, i);
 120                 }
 121                 for (int i = buffers->channels(); i < process_channels; ++i) {
 122                         extended_buffers->make_silent (i);
 123                 }
 124
 125                 buffers = extended_buffers;
 126         }
 127
 128         _in_frame->extended_data = new uint8_t*[process_channels];
 129         for (int i = 0; i < buffers->channels(); ++i) {
 130                 if (i < AV_NUM_DATA_POINTERS) {
 131                         _in_frame->data[i] = reinterpret_cast<uint8_t*> (buffers->data(i));
 132                 }
 133                 _in_frame->extended_data[i] = reinterpret_cast<uint8_t*> (buffers->data(i));
 134         }
 135
 136         _in_frame->nb_samples = buffers->frames ();
 137         _in_frame->format = AV_SAMPLE_FMT_FLTP;
 138         _in_frame->sample_rate = _sample_rate;
 139         _in_frame->ch_layout = _channel_layout;
 140 LIBDCP_DISABLE_WARNINGS
 141         _in_frame->channels = process_channels;
 142 LIBDCP_ENABLE_WARNINGS
 143
 144         int r = av_buffersrc_write_frame (_buffer_src_context, _in_frame);
 145
 146         delete[] _in_frame->extended_data;
 147         /* Reset extended_data to its original value so that av_frame_free
 148            does not try to free it.
 149         */
 150         _in_frame->extended_data = _in_frame->data;
 151
 152         if (r < 0) {
 153                 char buffer[256];
 154                 av_strerror (r, buffer, sizeof(buffer));
 155                 throw DecodeError (String::compose (N_("could not push buffer into filter chain (%1)"), &buffer[0]));
 156         }
 157
 158         while (true) {
 159                 if (av_buffersink_get_frame (_buffer_sink_context, _frame) < 0) {
 160                         break;
 161                 }
 162
 163                 /* We don't extract audio data here, since the only use of this class
 164                    is for ebur128.
 165                 */
 166
 167                 av_frame_unref (_frame);
 168         }
 169 }