src/lib/audio_merger.cc

   1 /*
   2     Copyright (C) 2013-2021 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
  21 /** @file  src/audio_merger.cc
  22  *  @brief AudioMerger class.
  23  */
  24
  25
  26 #include "audio_merger.h"
  27 #include "dcpomatic_time.h"
  28 #include <iostream>
  29
  30
  31 using std::cout;
  32 using std::list;
  33 using std::make_pair;
  34 using std::make_shared;
  35 using std::max;
  36 using std::min;
  37 using std::pair;
  38 using std::shared_ptr;
  39 using boost::optional;
  40 using namespace dcpomatic;
  41
  42
  43 AudioMerger::AudioMerger (int frame_rate)
  44         : _frame_rate (frame_rate)
  45 {
  46
  47 }
  48
  49
  50 Frame
  51 AudioMerger::frames (DCPTime t) const
  52 {
  53         return t.frames_floor (_frame_rate);
  54 }
  55
  56
  57 /** Pull audio up to a given time; after this call, no more data can be pushed
  58  *  before the specified time.
  59  *  @param time Time to pull up to.
  60  *  @return Blocks of merged audio up to `time'.
  61  */
  62 list<pair<shared_ptr<AudioBuffers>, DCPTime>>
  63 AudioMerger::pull (DCPTime time)
  64 {
  65         list<pair<shared_ptr<AudioBuffers>, DCPTime>> out;
  66
  67         list<Buffer> new_buffers;
  68
  69         _buffers.sort ([](Buffer const& a, Buffer const& b) {
  70                 return a.time < b.time;
  71         });
  72
  73         for (auto i: _buffers) {
  74                 if (i.period().to <= time) {
  75                         /* Completely within the pull period */
  76                         DCPOMATIC_ASSERT (i.audio->frames() > 0);
  77                         out.push_back (make_pair (i.audio, i.time));
  78                 } else if (i.time < time) {
  79                         /* Overlaps the end of the pull period */
  80                         int32_t const overlap = frames(DCPTime(time - i.time));
  81                         /* Though time > i.time, overlap could be 0 if the difference in time is less than one frame */
  82                         if (overlap > 0) {
  83                                 auto audio = make_shared<AudioBuffers>(i.audio, overlap, 0);
  84                                 out.push_back (make_pair(audio, i.time));
  85                                 i.audio->trim_start (overlap);
  86                                 i.time += DCPTime::from_frames(overlap, _frame_rate);
  87                                 DCPOMATIC_ASSERT (i.audio->frames() > 0);
  88                                 new_buffers.push_back (i);
  89                         }
  90                 } else {
  91                         /* Not involved */
  92                         DCPOMATIC_ASSERT (i.audio->frames() > 0);
  93                         new_buffers.push_back (i);
  94                 }
  95         }
  96
  97         _buffers = new_buffers;
  98
  99         for (auto const& i: out) {
 100                 DCPOMATIC_ASSERT (i.first->frames() > 0);
 101         }
 102
 103         return out;
 104 }
 105
 106
 107 /** Push some data into the merger at a given time */
 108 void
 109 AudioMerger::push (std::shared_ptr<const AudioBuffers> audio, DCPTime time)
 110 {
 111         DCPOMATIC_ASSERT (audio->frames() > 0);
 112
 113         DCPTimePeriod period (time, time + DCPTime::from_frames (audio->frames(), _frame_rate));
 114
 115         /* Mix any overlapping parts of this new block with existing ones */
 116         for (auto i: _buffers) {
 117                 auto overlap = i.period().overlap(period);
 118                 if (overlap) {
 119                         int32_t const offset = frames(DCPTime(overlap->from - i.time));
 120                         int32_t const frames_to_mix = frames(overlap->duration());
 121                         if (i.time < time) {
 122                                 i.audio->accumulate_frames(audio.get(), frames_to_mix, 0, offset);
 123                         } else {
 124                                 i.audio->accumulate_frames(audio.get(), frames_to_mix, offset, 0);
 125                         }
 126                 }
 127         }
 128
 129         list<DCPTimePeriod> periods;
 130         for (auto i: _buffers) {
 131                 periods.push_back (i.period());
 132         }
 133
 134         /* Add the non-overlapping parts */
 135         for (auto i: subtract(period, periods)) {
 136                 auto before = _buffers.end();
 137                 auto after = _buffers.end();
 138                 for (auto j = _buffers.begin(); j != _buffers.end(); ++j) {
 139                         if (j->period().to == i.from) {
 140                                 before = j;
 141                         }
 142                         if (j->period().from == i.to) {
 143                                 after = j;
 144                         }
 145                 }
 146
 147                 /* Get the part of audio that we want to use */
 148                 auto part = make_shared<AudioBuffers>(audio, frames(i.to) - frames(i.from), frames(DCPTime(i.from - time)));
 149
 150                 if (before == _buffers.end() && after == _buffers.end()) {
 151                         if (part->frames() > 0) {
 152                                 /* New buffer */
 153                                 _buffers.push_back (Buffer (part, time, _frame_rate));
 154                         }
 155                 } else if (before != _buffers.end() && after == _buffers.end()) {
 156                         /* We have an existing buffer before this one; append new data to it */
 157                         before->audio->append (part);
 158                 } else if (before ==_buffers.end() && after != _buffers.end()) {
 159                         /* We have an existing buffer after this one; append it to the new data and replace */
 160                         part->append (after->audio);
 161                         after->audio = part;
 162                         after->time = time;
 163                 } else {
 164                         /* We have existing buffers both before and after; coalesce them all */
 165                         before->audio->append (part);
 166                         before->audio->append (after->audio);
 167                         _buffers.erase (after);
 168                 }
 169         }
 170 }
 171
 172
 173 void
 174 AudioMerger::clear ()
 175 {
 176         _buffers.clear ();
 177 }