[FFmpeg-devel] [PATCH 2/2] pngdec: expose gAMA and cHRM chunks as AVMasteringDisplayMetadata

[Rostislav Pehlivanov]

Signed-off-by: Rostislav Pehlivanov <atomnuker at gmail.com>
---
 libavcodec/pngdec.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index 0d6612ccca..b7d9ded89c 100644
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -25,6 +25,7 @@
 #include "libavutil/bprint.h"
 #include "libavutil/imgutils.h"
 #include "libavutil/stereo3d.h"
+#include "libavutil/mastering_display_metadata.h"
 
 #include "avcodec.h"
 #include "bytestream.h"
@@ -1163,10 +1164,15 @@ static int decode_frame_common(AVCodecContext *avctx, PNGDecContext *s,
                                AVFrame *p, AVPacket *avpkt)
 {
     AVDictionary **metadatap = NULL;
+    AVMasteringDisplayMetadata mdm;
     uint32_t tag, length;
     int decode_next_dat = 0;
     int ret;
 
+    mdm.has_primaries = 0;
+    mdm.has_luminance = 0;
+    mdm.has_gamma     = 0;
+
     for (;;) {
         length = bytestream2_get_bytes_left(&s->gb);
         if (length <= 0) {
@@ -1287,6 +1293,41 @@ static int decode_frame_common(AVCodecContext *avctx, PNGDecContext *s,
                 goto fail;
             break;
         }
+        case MKTAG('c', 'H', 'R', 'M'): {
+            mdm.white_point[0].num = bytestream2_get_be32(&s->gb);
+            mdm.white_point[0].den = 100000;
+            mdm.white_point[1].num = bytestream2_get_be32(&s->gb);
+            mdm.white_point[1].den = 100000;
+
+            /* Red primaries */
+            mdm.display_primaries[0][0].num = bytestream2_get_be32(&s->gb);
+            mdm.display_primaries[0][0].den = 100000;
+            mdm.display_primaries[0][1].num = bytestream2_get_be32(&s->gb);
+            mdm.display_primaries[0][1].den = 100000;
+
+            /* Green primaries */
+            mdm.display_primaries[1][0].num = bytestream2_get_be32(&s->gb);
+            mdm.display_primaries[1][0].den = 100000;
+            mdm.display_primaries[1][1].num = bytestream2_get_be32(&s->gb);
+            mdm.display_primaries[1][1].den = 100000;
+
+            /* Blue primaries */
+            mdm.display_primaries[2][0].num = bytestream2_get_be32(&s->gb);
+            mdm.display_primaries[2][0].den = 100000;
+            mdm.display_primaries[2][1].num = bytestream2_get_be32(&s->gb);
+            mdm.display_primaries[2][1].den = 100000;
+
+            mdm.has_primaries = 1;
+            bytestream2_skip(&s->gb, 4); /* crc */
+            break;
+        }
+        case MKTAG('g', 'A', 'M', 'A'): {
+            mdm.gamma.num = bytestream2_get_be32(&s->gb);
+            mdm.gamma.den = 100000;
+            mdm.has_gamma = 1;
+            bytestream2_skip(&s->gb, 4); /* crc */
+            break;
+        }
         case MKTAG('I', 'E', 'N', 'D'):
             if (!(s->pic_state & PNG_ALLIMAGE))
                 av_log(avctx, AV_LOG_ERROR, "IEND without all image\n");
@@ -1305,6 +1346,11 @@ skip_tag:
     }
 exit_loop:
 
+    if (mdm.has_gamma || mdm.has_primaries) {
+        AVMasteringDisplayMetadata *new_mdm = av_mastering_display_metadata_create_side_data(p);
+        memcpy(new_mdm, &mdm, sizeof(AVMasteringDisplayMetadata));
+    }
+
     if (avctx->codec_id == AV_CODEC_ID_PNG &&
         avctx->skip_frame == AVDISCARD_ALL) {
         return 0;
-- 
2.14.1.821.g8fa685d3b7