src/lib/writer.cc

   1 /*
   2     Copyright (C) 2012 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 <libdcp/picture_asset.h>
  21 #include "writer.h"
  22 #include "compose.hpp"
  23 #include "film.h"
  24 #include "format.h"
  25 #include "log.h"
  26 #include "dcp_video_frame.h"
  27
  28 using std::make_pair;
  29 using std::pair;
  30 using boost::shared_ptr;
  31
  32 unsigned int const Writer::_maximum_frames_in_memory = 8;
  33
  34 Writer::Writer (shared_ptr<const Film> f)
  35         : _film (f)
  36         , _thread (0)
  37         , _finish (false)
  38         , _last_written_frame (-1)
  39 {
  40         _picture_asset.reset (
  41                 new libdcp::MonoPictureAsset (
  42                         _film->dir (_film->dcp_name()),
  43                         String::compose ("video_%1.mxf", 0),
  44                         DCPFrameRate (_film->frames_per_second()).frames_per_second,
  45                         _film->format()->dcp_size()
  46                         )
  47                 );
  48
  49         _picture_asset_writer = _picture_asset->start_write ();
  50
  51         _thread = new boost::thread (boost::bind (&Writer::thread, this));
  52 }
  53
  54 void
  55 Writer::write (shared_ptr<EncodedData> encoded, int frame)
  56 {
  57         boost::mutex::scoped_lock lock (_mutex);
  58         _queue.push_back (make_pair (encoded, frame));
  59         _condition.notify_all ();
  60 }
  61
  62 struct QueueSorter
  63 {
  64         bool operator() (pair<shared_ptr<EncodedData>, int> const & a, pair<shared_ptr<EncodedData>, int> const & b) {
  65                 return a.second < b.second;
  66         }
  67 };
  68
  69 void
  70 Writer::thread ()
  71 {
  72         while (1)
  73         {
  74                 boost::mutex::scoped_lock lock (_mutex);
  75
  76                 while (1) {
  77                         if (_finish ||
  78                             _queue.size() > _maximum_frames_in_memory ||
  79                             (!_queue.empty() && _queue.front().second == (_last_written_frame + 1))) {
  80
  81                                     break;
  82                             }
  83
  84                             TIMING ("writer sleeps with a queue of %1; %2 pending", _queue.size(), _pending.size());
  85                             _condition.wait (lock);
  86                             TIMING ("writer wakes with a queue of %1", _queue.size());
  87
  88                             _queue.sort (QueueSorter ());
  89                 }
  90
  91                 if (_finish && _queue.empty() && _pending.empty()) {
  92                         return;
  93                 }
  94
  95                 /* Write any frames that we can write; i.e. those that are in sequence */
  96                 while (!_queue.empty() && _queue.front().second == (_last_written_frame + 1)) {
  97                         pair<boost::shared_ptr<EncodedData>, int> encoded = _queue.front ();
  98                         _queue.pop_front ();
  99
 100                         lock.unlock ();
 101                         _film->log()->log (String::compose ("Writer writes %1 to MXF", encoded.second));
 102                         if (encoded.first) {
 103                                 _picture_asset_writer->write (encoded.first->data(), encoded.first->size());
 104                                 _last_written = encoded.first;
 105                         } else {
 106                                 _picture_asset_writer->write (_last_written->data(), _last_written->size());
 107                         }
 108                         lock.lock ();
 109
 110                         ++_last_written_frame;
 111                 }
 112
 113                 while (_queue.size() > _maximum_frames_in_memory) {
 114                         /* Too many frames in memory which can't yet be written to the stream.
 115                            Put some to disk.
 116                         */
 117
 118                         pair<boost::shared_ptr<EncodedData>, int> encoded = _queue.back ();
 119                         _queue.pop_back ();
 120                         if (!encoded.first) {
 121                                 /* This is a `repeat-last' frame, so no need to write it to disk */
 122                                 continue;
 123                         }
 124
 125                         lock.unlock ();
 126                         _film->log()->log (String::compose ("Writer full (awaiting %1); pushes %2 to disk", _last_written_frame + 1, encoded.second));
 127                         encoded.first->write (_film, encoded.second);
 128                         lock.lock ();
 129
 130                         _pending.push_back (encoded.second);
 131                 }
 132
 133                 while (_queue.size() < _maximum_frames_in_memory && !_pending.empty()) {
 134                         /* We have some space in memory.  Fetch some frames back off disk. */
 135
 136                         _pending.sort ();
 137                         int const fetch = _pending.front ();
 138
 139                         lock.unlock ();
 140                         _film->log()->log (String::compose ("Writer pulls %1 back from disk", fetch));
 141                         shared_ptr<EncodedData> encoded;
 142                         if (boost::filesystem::exists (_film->frame_out_path (fetch, false))) {
 143                                 /* It's an actual frame (not a repeat-last); load it in */
 144                                 encoded.reset (new EncodedData (_film->frame_out_path (fetch, false)));
 145                         }
 146                         lock.lock ();
 147
 148                         _queue.push_back (make_pair (encoded, fetch));
 149                         _pending.remove (fetch);
 150                 }
 151         }
 152
 153 }
 154
 155 void
 156 Writer::finish ()
 157 {
 158         if (!_thread) {
 159                 return;
 160         }
 161
 162         boost::mutex::scoped_lock lock (_mutex);
 163         _finish = true;
 164         _condition.notify_all ();
 165         lock.unlock ();
 166
 167         _thread->join ();
 168         delete _thread;
 169         _thread = 0;
 170
 171         _picture_asset_writer->finalize ();
 172 }
 173
 174 /** Tell the writer that frame `f' should be a repeat of the frame before it */
 175 void
 176 Writer::repeat (int f)
 177 {
 178         boost::mutex::scoped_lock lock (_mutex);
 179         _queue.push_back (make_pair (shared_ptr<EncodedData> (), f));
 180 }