Add writer class to pull some stuff out of Encoder.

1 files changed, 180 insertions, 0 deletions

diff --git a/src/lib/writer.cc b/src/lib/writer.cc
new file mode 100644
index 000000000..0381ee378
--- /dev/null
+++ b/src/lib/writer.cc
@@ -0,0 +1,180 @@
+/*
+    Copyright (C) 2012 Carl Hetherington <cth@carlh.net>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#include <libdcp/picture_asset.h>
+#include "writer.h"
+#include "compose.hpp"
+#include "film.h"
+#include "format.h"
+#include "log.h"
+#include "dcp_video_frame.h"
+
+using std::make_pair;
+using std::pair;
+using boost::shared_ptr;
+
+unsigned int const Writer::_maximum_frames_in_memory = 8;
+
+Writer::Writer (shared_ptr<const Film> f)
+	: _film (f)
+	, _thread (0)
+	, _finish (false)
+	, _last_written_frame (-1)
+{
+	_picture_asset.reset (
+		new libdcp::MonoPictureAsset (
+			_film->dir (_film->dcp_name()),
+			String::compose ("video_%1.mxf", 0),
+			DCPFrameRate (_film->frames_per_second()).frames_per_second,
+			_film->format()->dcp_size()
+			)
+		);
+	
+	_picture_asset_writer = _picture_asset->start_write ();
+
+	_thread = new boost::thread (boost::bind (&Writer::thread, this));
+}
+
+void
+Writer::write (shared_ptr<EncodedData> encoded, int frame)
+{
+	boost::mutex::scoped_lock lock (_mutex);
+	_queue.push_back (make_pair (encoded, frame));
+	_condition.notify_all ();
+}
+
+struct QueueSorter
+{
+	bool operator() (pair<shared_ptr<EncodedData>, int> const & a, pair<shared_ptr<EncodedData>, int> const & b) {
+		return a.second < b.second;
+	}
+};
+
+void
+Writer::thread ()
+{
+	while (1)
+	{
+		boost::mutex::scoped_lock lock (_mutex);
+
+		while (1) {
+			if (_finish ||
+			    _queue.size() > _maximum_frames_in_memory ||
+			    (!_queue.empty() && _queue.front().second == (_last_written_frame + 1))) {
+				    
+				    break;
+			    }
+
+			    TIMING ("writer sleeps with a queue of %1; %2 pending", _queue.size(), _pending.size());
+			    _condition.wait (lock);
+			    TIMING ("writer wakes with a queue of %1", _queue.size());
+
+			    _queue.sort (QueueSorter ());
+		}
+
+		if (_finish && _queue.empty() && _pending.empty()) {
+			return;
+		}
+
+		/* Write any frames that we can write; i.e. those that are in sequence */
+		while (!_queue.empty() && _queue.front().second == (_last_written_frame + 1)) {
+			pair<boost::shared_ptr<EncodedData>, int> encoded = _queue.front ();
+			_queue.pop_front ();
+
+			lock.unlock ();
+			_film->log()->log (String::compose ("Writer writes %1 to MXF", encoded.second));
+			if (encoded.first) {
+				_picture_asset_writer->write (encoded.first->data(), encoded.first->size());
+				_last_written = encoded.first;
+			} else {
+				_picture_asset_writer->write (_last_written->data(), _last_written->size());
+			}
+			lock.lock ();
+
+			++_last_written_frame;
+		}
+
+		while (_queue.size() > _maximum_frames_in_memory) {
+			/* Too many frames in memory which can't yet be written to the stream.
+			   Put some to disk.
+			*/
+
+			pair<boost::shared_ptr<EncodedData>, int> encoded = _queue.back ();
+			_queue.pop_back ();
+			if (!encoded.first) {
+				/* This is a `repeat-last' frame, so no need to write it to disk */
+				continue;
+			}
+
+			lock.unlock ();
+			_film->log()->log (String::compose ("Writer full (awaiting %1); pushes %2 to disk", _last_written_frame + 1, encoded.second));
+			encoded.first->write (_film, encoded.second);
+			lock.lock ();
+
+			_pending.push_back (encoded.second);
+		}
+
+		while (_queue.size() < _maximum_frames_in_memory && !_pending.empty()) {
+			/* We have some space in memory.  Fetch some frames back off disk. */
+
+			_pending.sort ();
+			int const fetch = _pending.front ();
+
+			lock.unlock ();
+			_film->log()->log (String::compose ("Writer pulls %1 back from disk", fetch));
+			shared_ptr<EncodedData> encoded;
+			if (boost::filesystem::exists (_film->frame_out_path (fetch, false))) {
+				/* It's an actual frame (not a repeat-last); load it in */
+				encoded.reset (new EncodedData (_film->frame_out_path (fetch, false)));
+			}
+			lock.lock ();
+
+			_queue.push_back (make_pair (encoded, fetch));
+			_pending.remove (fetch);
+		}
+	}
+
+}
+
+void
+Writer::finish ()
+{
+	if (!_thread) {
+		return;
+	}
+	
+	boost::mutex::scoped_lock lock (_mutex);
+	_finish = true;
+	_condition.notify_all ();
+	lock.unlock ();
+
+	_thread->join ();
+	delete _thread;
+	_thread = 0;
+
+	_picture_asset_writer->finalize ();
+}
+
+/** Tell the writer that frame `f' should be a repeat of the frame before it */
+void
+Writer::repeat (int f)
+{
+	boost::mutex::scoped_lock lock (_mutex);
+	_queue.push_back (make_pair (shared_ptr<EncodedData> (), f));
+}