Add image_as_jpeg()

[dcpomatic.git] / src / lib / image_jpeg.cc

diff --git a/src/lib/image_jpeg.cc b/src/lib/image_jpeg.cc
new file mode 100644 (file)
index 0000000..28bbb75
--- /dev/null
+++ b/src/lib/image_jpeg.cc
@@ -0,0 +1,135 @@
+/*
+    Copyright (C) 2021 Carl Hetherington <cth@carlh.net>
+
+    This file is part of DCP-o-matic.
+
+    DCP-o-matic 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.
+
+    DCP-o-matic 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 DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+
+#include "dcpomatic_assert.h"
+#include "exceptions.h"
+#include "image.h"
+#include <jpeglib.h>
+
+#include "i18n.h"
+
+
+using std::shared_ptr;
+
+
+struct destination_mgr
+{
+       jpeg_destination_mgr pub;
+       std::vector<uint8_t>* data;
+};
+
+
+static void
+init_destination (j_compress_ptr)
+{
+
+}
+
+
+/* Empty the output buffer (i.e. make more space for data); we'll make
+ * the output buffer bigger instead.
+ */
+static boolean
+empty_output_buffer (j_compress_ptr state)
+{
+       auto dest = reinterpret_cast<destination_mgr*> (state->dest);
+
+       auto const old_size = dest->data->size();
+       dest->data->resize (old_size * 2);
+
+       dest->pub.next_output_byte = dest->data->data() + old_size;
+       dest->pub.free_in_buffer = old_size;
+
+       return TRUE;
+}
+
+
+static void
+term_destination (j_compress_ptr state)
+{
+       auto dest = reinterpret_cast<destination_mgr*> (state->dest);
+
+       dest->data->resize (dest->data->size() - dest->pub.free_in_buffer);
+}
+
+
+void
+error_exit (j_common_ptr)
+{
+       throw EncodeError (N_("JPEG encoding error"));
+}
+
+
+dcp::ArrayData
+image_as_jpeg (shared_ptr<const Image> image, int quality)
+{
+       if (image->pixel_format() != AV_PIX_FMT_RGB24) {
+               return image_as_jpeg(
+                       Image::ensure_alignment(image, Image::Alignment::PADDED)->convert_pixel_format(dcp::YUVToRGB::REC709, AV_PIX_FMT_RGB24, Image::Alignment::PADDED, false),
+                       quality
+                       );
+       }
+
+       struct jpeg_compress_struct compress;
+       struct jpeg_error_mgr error;
+
+       compress.err = jpeg_std_error (&error);
+       error.error_exit = error_exit;
+       jpeg_create_compress (&compress);
+
+       auto mgr = new destination_mgr;
+       compress.dest = reinterpret_cast<jpeg_destination_mgr*>(mgr);
+
+       mgr->pub.init_destination = init_destination;
+       mgr->pub.empty_output_buffer = empty_output_buffer;
+       mgr->pub.term_destination = term_destination;
+
+       std::vector<uint8_t> data(4096);
+       mgr->data = &data;
+       mgr->pub.next_output_byte = data.data();
+       mgr->pub.free_in_buffer = data.size();
+
+       compress.image_width = image->size().width;
+       compress.image_height = image->size().height;
+       compress.input_components = 3;
+       compress.in_color_space = JCS_RGB;
+
+       jpeg_set_defaults (&compress);
+       jpeg_set_quality (&compress, quality, TRUE);
+
+       jpeg_start_compress (&compress, TRUE);
+
+       JSAMPROW row[1];
+       auto const source_data = image->data()[0];
+       auto const source_stride = image->stride()[0];
+       for (auto y = 0U; y < compress.image_height; ++y) {
+               row[0] = source_data + y * source_stride;
+               jpeg_write_scanlines (&compress, row, 1);
+       }
+
+       jpeg_finish_compress (&compress);
+       delete mgr;
+       jpeg_destroy_compress (&compress);
+
+       return dcp::ArrayData (data.data(), data.size());
+}
+
+