Grok: fix hang when encoding with burned-in subtitles and no colour conversion

When a source has no colour conversion (e.g. an already-XYZ J2K DCP),
every frame normally bypasses encoding via the has_j2k() fast-path.  But
has_j2k() returns false as soon as _text is set, so the first
burned-subtitle frame goes through the encode path and hits the
colour_conversion assertion in the Grok variant of
convert_to_xyz(), killing the Grok threads one by one until the queue
can no longer drain.

Handle the no-conversion case the same way the local convert_to_xyz()
overload does: the image is already XYZ12LE, so copy it straight into
the destination buffer.

1 files changed, 25 insertions, 9 deletions

diff --git a/src/lib/dcp_video.cc b/src/lib/dcp_video.cc
index 775298091..66f4a3c4c 100644
--- a/src/lib/dcp_video.cc
+++ b/src/lib/dcp_video.cc
@@ -135,16 +135,32 @@ DCPVideo::get_size() const
 void
 DCPVideo::convert_to_xyz(uint16_t* dst) const
 {
-	DCPOMATIC_ASSERT(_frame->colour_conversion());
+	auto conversion = [](AVPixelFormat fmt) {
+		return fmt == AV_PIX_FMT_XYZ12LE ? AV_PIX_FMT_XYZ12LE : AV_PIX_FMT_RGB48LE;
+	};
 
-	auto image = _frame->image(force(AV_PIX_FMT_RGB48LE), VideoRange::FULL, false);
-	dcp::rgb_to_xyz(
-		image->data()[0],
-		dst,
-		image->size(),
-		image->stride()[0],
-		_frame->colour_conversion().get()
-		);
+	auto image = _frame->image(conversion, VideoRange::FULL, false);
+
+	if (_frame->colour_conversion()) {
+		dcp::rgb_to_xyz(
+			image->data()[0],
+			dst,
+			image->size(),
+			image->stride()[0],
+			_frame->colour_conversion().get()
+			);
+	} else {
+		auto const size = image->size();
+		auto const row_bytes = static_cast<size_t>(size.width) * 3 * sizeof(uint16_t);
+		auto src = image->data()[0];
+		auto const src_stride = image->stride()[0];
+		auto out = reinterpret_cast<uint8_t*>(dst);
+		for (int y = 0; y < size.height; ++y) {
+			memcpy(out, src, row_bytes);
+			src += src_stride;
+			out += row_bytes;
+		}
+	}
 }