[FFmpeg-devel] [PATCH] avformat/mxfdec: Read video range from PictureDescriptor

[Harry Mallon]

Thanks to Tomas for reviewing these MXF patches. Here is another. FFMPEG already writes out the three range tags. This just reads them in.

Best,
Harry

>From c49f77d1e887d8c84752df11213dcf5afa8f761e Mon Sep 17 00:00:00 2001

From: Harry Mallon <harry.mallon at codex.online>
Date: Wed, 12 Aug 2020 10:26:23 +0100
Subject: [PATCH] avformat/mxfdec: Read video range from PictureDescriptor

* Capture black_ref, white_ref and color_range and recognise
  full and narrow range.

Signed-off-by: Harry Mallon <harry.mallon at codex.online>
---
 libavformat/mxfdec.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
index fa9dcab658..9d2563239e 100644
--- a/libavformat/mxfdec.c
+++ b/libavformat/mxfdec.c
@@ -201,6 +201,9 @@ typedef struct MXFDescriptor {
     int bits_per_sample;
     int64_t duration; /* ContainerDuration optional property */
     unsigned int component_depth;
+    unsigned int black_ref_level;
+    unsigned int white_ref_level;
+    unsigned int color_range;
     unsigned int horiz_subsampling;
     unsigned int vert_subsampling;
     UID *sub_descriptors_refs;
@@ -1230,6 +1233,15 @@ static int mxf_read_generic_descriptor(void *arg, AVIOContext *pb, int tag, int
     case 0x3302:
         descriptor->horiz_subsampling = avio_rb32(pb);
         break;
+    case 0x3304:
+        descriptor->black_ref_level = avio_rb32(pb);
+        break;
+    case 0x3305:
+        descriptor->white_ref_level = avio_rb32(pb);
+        break;
+    case 0x3306:
+        descriptor->color_range = avio_rb32(pb);
+        break;
     case 0x3308:
         descriptor->vert_subsampling = avio_rb32(pb);
         break;
@@ -2557,6 +2569,16 @@ static int mxf_parse_structural_metadata(MXFContext *mxf)
             st->codecpar->color_primaries = mxf_get_codec_ul(ff_mxf_color_primaries_uls, &descriptor->color_primaries_ul)->id;
             st->codecpar->color_trc       = mxf_get_codec_ul(ff_mxf_color_trc_uls, &descriptor->color_trc_ul)->id;
             st->codecpar->color_space     = mxf_get_codec_ul(ff_mxf_color_space_uls, &descriptor->color_space_ul)->id;
+            if (descriptor->black_ref_level == 0 &&
+                descriptor->white_ref_level == ((1<<descriptor->component_depth) - 1) &&
+                descriptor->color_range     == ((1<<descriptor->component_depth) - 1)) {
+                    st->codecpar->color_range = AVCOL_RANGE_JPEG;
+            }
+            else if (descriptor->black_ref_level == (1  <<(descriptor->component_depth - 4)) &&
+                     descriptor->white_ref_level == (235<<(descriptor->component_depth - 8)) &&
+                     descriptor->color_range     == ((14<<(descriptor->component_depth - 4)) + 1)) {
+                    st->codecpar->color_range = AVCOL_RANGE_MPEG;
+            }
             if (descriptor->mastering) {
                 ret = av_stream_add_side_data(st, AV_PKT_DATA_MASTERING_DISPLAY_METADATA,
                                               (uint8_t *)descriptor->mastering,
-- 
2.28.0