src/lib/audio_merger.cc

   1 /*
   2     Copyright (C) 2013-2017 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 /** @file  src/audio_merger.cc
  21  *  @brief AudioMerger class.
  22  */
  23
  24 #include "audio_merger.h"
  25 #include "dcpomatic_time.h"
  26 #include <iostream>
  27
  28 using std::pair;
  29 using std::min;
  30 using std::max;
  31 using std::list;
  32 using std::cout;
  33 using std::make_pair;
  34 using std::shared_ptr;
  35 using boost::optional;
  36 using namespace dcpomatic;
  37
  38 AudioMerger::AudioMerger (int frame_rate)
  39         : _frame_rate (frame_rate)
  40 {
  41
  42 }
  43
  44 Frame
  45 AudioMerger::frames (DCPTime t) const
  46 {
  47         return t.frames_floor (_frame_rate);
  48 }
  49
  50 /** Pull audio up to a given time; after this call, no more data can be pushed
  51  *  before the specified time.
  52  *  @param time Time to pull up to.
  53  *  @return Blocks of merged audio up to `time'.
  54  */
  55 list<pair<shared_ptr<AudioBuffers>, DCPTime> >
  56 AudioMerger::pull (DCPTime time)
  57 {
  58         list<pair<shared_ptr<AudioBuffers>, DCPTime> > out;
  59
  60         list<Buffer> new_buffers;
  61
  62         _buffers.sort (AudioMerger::BufferComparator());
  63         for (auto i: _buffers) {
  64                 if (i.period().to <= time) {
  65                         /* Completely within the pull period */
  66                         DCPOMATIC_ASSERT (i.audio->frames() > 0);
  67                         out.push_back (make_pair (i.audio, i.time));
  68                 } else if (i.time < time) {
  69                         /* Overlaps the end of the pull period */
  70                         int32_t const overlap = frames(DCPTime(time - i.time));
  71                         /* Though time > i.time, overlap could be 0 if the difference in time is less than one frame */
  72                         if (overlap > 0) {
  73                                 shared_ptr<AudioBuffers> audio(new AudioBuffers(i.audio, overlap, 0));
  74                                 out.push_back (make_pair(audio, i.time));
  75                                 i.audio->trim_start (overlap);
  76                                 i.time += DCPTime::from_frames(overlap, _frame_rate);
  77                                 DCPOMATIC_ASSERT (i.audio->frames() > 0);
  78                                 new_buffers.push_back (i);
  79                         }
  80                 } else {
  81                         /* Not involved */
  82                         DCPOMATIC_ASSERT (i.audio->frames() > 0);
  83                         new_buffers.push_back (i);
  84                 }
  85         }
  86
  87         _buffers = new_buffers;
  88
  89         for (list<pair<shared_ptr<AudioBuffers>, DCPTime> >::const_iterator i = out.begin(); i != out.end(); ++i) {
  90                 DCPOMATIC_ASSERT (i->first->frames() > 0);
  91         }
  92
  93         return out;
  94 }
  95
  96 /** Push some data into the merger at a given time */
  97 void
  98 AudioMerger::push (std::shared_ptr<const AudioBuffers> audio, DCPTime time)
  99 {
 100         DCPOMATIC_ASSERT (audio->frames() > 0);
 101
 102         DCPTimePeriod period (time, time + DCPTime::from_frames (audio->frames(), _frame_rate));
 103
 104         /* Mix any overlapping parts of this new block with existing ones */
 105         for (auto i: _buffers) {
 106                 optional<DCPTimePeriod> overlap = i.period().overlap (period);
 107                 if (overlap) {
 108                         int32_t const offset = frames(DCPTime(overlap->from - i.time));
 109                         int32_t const frames_to_mix = frames(overlap->duration());
 110                         if (i.time < time) {
 111                                 i.audio->accumulate_frames(audio.get(), frames_to_mix, 0, offset);
 112                         } else {
 113                                 i.audio->accumulate_frames(audio.get(), frames_to_mix, offset, 0);
 114                         }
 115                 }
 116         }
 117
 118         list<DCPTimePeriod> periods;
 119         for (auto i: _buffers) {
 120                 periods.push_back (i.period ());
 121         }
 122
 123         /* Add the non-overlapping parts */
 124         for (auto i: subtract(period, periods)) {
 125                 list<Buffer>::iterator before = _buffers.end();
 126                 list<Buffer>::iterator after = _buffers.end();
 127                 for (list<Buffer>::iterator j = _buffers.begin(); j != _buffers.end(); ++j) {
 128                         if (j->period().to == i.from) {
 129                                 before = j;
 130                         }
 131                         if (j->period().from == i.to) {
 132                                 after = j;
 133                         }
 134                 }
 135
 136                 /* Get the part of audio that we want to use */
 137                 shared_ptr<AudioBuffers> part (new AudioBuffers(audio, frames(i.to) - frames(i.from), frames(DCPTime(i.from - time))));
 138
 139                 if (before == _buffers.end() && after == _buffers.end()) {
 140                         if (part->frames() > 0) {
 141                                 /* New buffer */
 142                                 _buffers.push_back (Buffer (part, time, _frame_rate));
 143                         }
 144                 } else if (before != _buffers.end() && after == _buffers.end()) {
 145                         /* We have an existing buffer before this one; append new data to it */
 146                         before->audio->append (part);
 147                 } else if (before ==_buffers.end() && after != _buffers.end()) {
 148                         /* We have an existing buffer after this one; append it to the new data and replace */
 149                         part->append (after->audio);
 150                         after->audio = part;
 151                         after->time = time;
 152                 } else {
 153                         /* We have existing buffers both before and after; coalesce them all */
 154                         before->audio->append (part);
 155                         before->audio->append (after->audio);
 156                         _buffers.erase (after);
 157                 }
 158         }
 159 }
 160
 161 void
 162 AudioMerger::clear ()
 163 {
 164         _buffers.clear ();
 165 }