From: Carl Hetherington <cth@carlh.net>
Date: Fri, 15 Oct 2021 20:33:46 +0000 (+0200)
Subject: Always block waiting for audio when exporting.
X-Git-Tag: checked-for-v2.16.x~248
X-Git-Url: https://git.carlh.net/gitweb/?p=dcpomatic.git;a=commitdiff_plain;h=4d0356840c2f400b0376230a3d07f57897275f99

Always block waiting for audio when exporting.

Otherwise if there is non available we'll insert silence and potentially
push the audio out of sync (late).  May help with #2098.
---

diff --git a/src/lib/butler.cc b/src/lib/butler.cc
index f19e1e080..686fa9f72 100644
--- a/src/lib/butler.cc
+++ b/src/lib/butler.cc
@@ -373,13 +373,21 @@ Butler::audio (shared_ptr<AudioBuffers> audio, DCPTime time, int frame_rate)
 }
 
 
-/** Try to get `frames' frames of audio and copy it into `out'.  Silence
- *  will be filled if no audio is available.
- *  @return time of this audio, or unset if there was a buffer underrun.
+/** Try to get `frames' frames of audio and copy it into `out'.
+ *  @param behaviour BLOCKING if we should block until audio is available.  If behaviour is NON_BLOCKING
+ *  and no audio is immediately available the buffer will be filled with silence and boost::none
+ *  will be returned.
+ *  @return time of this audio, or unset if blocking was false and no data was available.
  */
 optional<DCPTime>
-Butler::get_audio (float* out, Frame frames)
+Butler::get_audio (Behaviour behaviour, float* out, Frame frames)
 {
+	boost::mutex::scoped_lock lm (_mutex);
+
+	while (behaviour == Behaviour::BLOCKING && !_finished && !_died && _audio.size() < frames) {
+		_arrived.wait (lm);
+	}
+
 	auto t = _audio.get (out, _audio_channels, frames);
 	_summon.notify_all ();
 	return t;
diff --git a/src/lib/butler.h b/src/lib/butler.h
index 529b7383d..c7e71658d 100644
--- a/src/lib/butler.h
+++ b/src/lib/butler.h
@@ -78,7 +78,7 @@ public:
 	};
 
 	std::pair<std::shared_ptr<PlayerVideo>, dcpomatic::DCPTime> get_video (Behaviour behaviour, Error* e = nullptr);
-	boost::optional<dcpomatic::DCPTime> get_audio (float* out, Frame frames);
+	boost::optional<dcpomatic::DCPTime> get_audio (Behaviour behaviour, float* out, Frame frames);
 	boost::optional<TextRingBuffers::Data> get_closed_caption ();
 
 	void disable_audio ();
diff --git a/src/lib/ffmpeg_encoder.cc b/src/lib/ffmpeg_encoder.cc
index d29e191ed..6dc3a83d4 100644
--- a/src/lib/ffmpeg_encoder.cc
+++ b/src/lib/ffmpeg_encoder.cc
@@ -204,7 +204,7 @@ FFmpegEncoder::go ()
 
 		waker.nudge ();
 
-		_butler->get_audio (interleaved.data(), audio_frames);
+		_butler->get_audio (Butler::Behaviour::BLOCKING, interleaved.data(), audio_frames);
 		/* XXX: inefficient; butler interleaves and we deinterleave again */
 		float* p = interleaved.data();
 		for (int j = 0; j < audio_frames; ++j) {
diff --git a/src/wx/film_viewer.cc b/src/wx/film_viewer.cc
index 22de7b593..e678c6aa3 100644
--- a/src/wx/film_viewer.cc
+++ b/src/wx/film_viewer.cc
@@ -649,7 +649,7 @@ int
 FilmViewer::audio_callback (void* out_p, unsigned int frames)
 {
 	while (true) {
-		auto t = _butler->get_audio (reinterpret_cast<float*> (out_p), frames);
+		auto t = _butler->get_audio (Butler::Behaviour::NON_BLOCKING, reinterpret_cast<float*> (out_p), frames);
 		if (!t || DCPTime(uncorrected_time() - *t) < one_video_frame()) {
 			/* There was an underrun or this audio is on time; carry on */
 			break;
diff --git a/test/butler_test.cc b/test/butler_test.cc
index e57779334..3d524a3b2 100644
--- a/test/butler_test.cc
+++ b/test/butler_test.cc
@@ -67,7 +67,7 @@ BOOST_AUTO_TEST_CASE (butler_test1)
 	/* XXX: check the frame contents */
 
 	float buffer[256 * 6];
-	BOOST_REQUIRE (butler.get_audio(buffer, 256) == DCPTime());
+	BOOST_REQUIRE (butler.get_audio(Butler::Behaviour::BLOCKING, buffer, 256) == DCPTime());
 	for (int i = 0; i < 256; ++i) {
 		BOOST_REQUIRE_EQUAL (buffer[i * 6 + 0], 0);
 		BOOST_REQUIRE_EQUAL (buffer[i * 6 + 1], 0);
diff --git a/test/dcp_playback_test.cc b/test/dcp_playback_test.cc
index 892825753..5117be9ed 100644
--- a/test/dcp_playback_test.cc
+++ b/test/dcp_playback_test.cc
@@ -62,7 +62,7 @@ BOOST_AUTO_TEST_CASE (dcp_playback_test)
 			break;
 		}
 		/* assuming DCP is 24fps/48kHz */
-		butler->get_audio (audio_buffer.data(), 2000);
+		butler->get_audio (Butler::Behaviour::BLOCKING, audio_buffer.data(), 2000);
 		p.first->image(bind(&PlayerVideo::force, _1, AV_PIX_FMT_RGB24), VideoRange::FULL, true);
 	}
 }