From 8628ff82abf4c22b480974eded4397db4a1480cb Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Thu, 1 Mar 2018 20:19:26 +0000
Subject: [PATCH] Avoid a memcpy in the export code.

---
 src/lib/ffmpeg_encoder.cc | 19 ++++++++++++++-----
 src/lib/ffmpeg_encoder.h  |  8 ++++++++
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/src/lib/ffmpeg_encoder.cc b/src/lib/ffmpeg_encoder.cc
index a8a033990..6b41cfbe0 100644
--- a/src/lib/ffmpeg_encoder.cc
+++ b/src/lib/ffmpeg_encoder.cc
@@ -280,12 +280,9 @@ FFmpegEncoder::video (shared_ptr<PlayerVideo> video, DCPTime time)
 	AVFrame* frame = av_frame_alloc ();
 	DCPOMATIC_ASSERT (frame);
 
+	_pending_images[image->data()[0]] = image;
 	for (int i = 0; i < 3; ++i) {
-		size_t const size = image->stride()[i] * image->sample_size(i).height;
-		AVBufferRef* buffer = av_buffer_alloc (size);
-		DCPOMATIC_ASSERT (buffer);
-		/* XXX: inefficient */
-		memcpy (buffer->data, image->data()[i], size);
+		AVBufferRef* buffer = av_buffer_create(image->data()[i], image->stride()[i] * image->size().height, &buffer_free, this, 0);
 		frame->buf[i] = av_buffer_ref (buffer);
 		frame->data[i] = buffer->data;
 		frame->linesize[i] = image->stride()[i];
@@ -431,3 +428,15 @@ FFmpegEncoder::frames_done () const
 	boost::mutex::scoped_lock lm (_mutex);
 	return _last_time.frames_round (_film->video_frame_rate ());
 }
+
+void
+FFmpegEncoder::buffer_free (void* opaque, uint8_t* data)
+{
+	reinterpret_cast<FFmpegEncoder*>(opaque)->buffer_free2(data);
+}
+
+void
+FFmpegEncoder::buffer_free2 (uint8_t* data)
+{
+	_pending_images.erase (data);
+}
diff --git a/src/lib/ffmpeg_encoder.h b/src/lib/ffmpeg_encoder.h
index 5e6dcecf7..43c0d948b 100644
--- a/src/lib/ffmpeg_encoder.h
+++ b/src/lib/ffmpeg_encoder.h
@@ -61,6 +61,9 @@ private:
 
 	void audio_frame (int size);
 
+	static void buffer_free(void* opaque, uint8_t* data);
+	void buffer_free2(uint8_t* data);
+
 	AVCodec* _video_codec;
 	AVCodecContext* _video_codec_context;
 	AVCodec* _audio_codec;
@@ -90,6 +93,11 @@ private:
 
 	boost::shared_ptr<Butler> _butler;
 
+	/** Store of shared_ptr<Image> to keep them alive whilst raw pointers into
+	    their data have been passed to FFmpeg.
+	*/
+	std::map<uint8_t*, boost::shared_ptr<const Image> > _pending_images;
+
 	static int _video_stream_index;
 	static int _audio_stream_index;
 };
-- 
2.30.2