[FFmpeg-devel] [PATCH] avformat/mxfenc: Write color metadata to MXF

[Harry Mallon]

I attach a patch to apply the colour metadata that was read in my previous commit during mxf encoding. ffmpeg previously wrote the transfer characteristic only, and not for all supported transfer curves. Now it will do transfer characteristic, colour primaries and colour space.

Best,
Harry

>From de460620b73379d5a869baa98e49a5d0f67d9ebb Mon Sep 17 00:00:00 2001

From: Harry Mallon <harry.mallon at codex.online>
Date: Tue, 28 Jul 2020 10:33:19 +0100
Subject: [PATCH] avformat/mxfenc: Write color metadata to MXF

Writes color_primaries, color_trc and color_space to mxf
headers. ULs are from https://registry.smpte-ra.org/ site.

Signed-off-by: Harry Mallon <harry.mallon at codex.online>
---
 libavformat/mxfenc.c | 58 ++++++++++++++++----------------------------
 1 file changed, 21 insertions(+), 37 deletions(-)

diff --git a/libavformat/mxfenc.c b/libavformat/mxfenc.c
index 5a3a609bf6..a38fa6b983 100644
--- a/libavformat/mxfenc.c
+++ b/libavformat/mxfenc.c
@@ -553,11 +553,10 @@ static void mxf_write_metadata_key(AVIOContext *pb, unsigned int value)
     avio_wb24(pb, value);
 }
 
-static const MXFCodecUL *mxf_get_data_definition_ul(int type)
+static const MXFCodecUL *mxf_get_codec_ul_by_id(const MXFCodecUL *uls, int id)
 {
-    const MXFCodecUL *uls = ff_mxf_data_definition_uls;
     while (uls->uid[0]) {
-        if (type == uls->id)
+        if (id == uls->id)
             break;
         uls++;
     }
@@ -847,7 +846,7 @@ static void mxf_write_common_fields(AVFormatContext *s, AVStream *st)
     if (st == mxf->timecode_track)
         avio_write(pb, smpte_12m_timecode_track_data_ul, 16);
     else {
-        const MXFCodecUL *data_def_ul = mxf_get_data_definition_ul(st->codecpar->codec_type);
+        const MXFCodecUL *data_def_ul = mxf_get_codec_ul_by_id(ff_mxf_data_definition_uls, st->codecpar->codec_type);
         avio_write(pb, data_def_ul->uid, 16);
     }
 
@@ -1049,34 +1048,6 @@ static const UID mxf_generic_sound_descriptor_key = { 0x06,0x0E,0x2B,0x34,0x02,0
 
 static const UID mxf_avc_subdescriptor_key = { 0x06,0x0E,0x2B,0x34,0x02,0x53,0x01,0x01,0x0d,0x01,0x01,0x01,0x01,0x01,0x6E,0x00 };
 
-static int get_trc(UID ul, enum AVColorTransferCharacteristic trc)
-{
-    switch (trc){
-    case AVCOL_TRC_GAMMA28   :
-    case AVCOL_TRC_GAMMA22   :
-        memcpy(ul, ((UID){0x06,0x0E,0x2B,0x34,0x04,0x01,0x01,0x01,0x04,0x01,0x01,0x01,0x01,0x01,0x00,0x00}), 16);
-        return 0;
-    case AVCOL_TRC_BT709     :
-    case AVCOL_TRC_SMPTE170M :
-        memcpy(ul, ((UID){0x06,0x0E,0x2B,0x34,0x04,0x01,0x01,0x01,0x04,0x01,0x01,0x01,0x01,0x02,0x00,0x00}), 16);
-        return 0;
-    case AVCOL_TRC_SMPTE240M :
-        memcpy(ul, ((UID){0x06,0x0E,0x2B,0x34,0x04,0x01,0x01,0x01,0x04,0x01,0x01,0x01,0x01,0x03,0x00,0x00}), 16);
-        return 0;
-    case AVCOL_TRC_BT1361_ECG:
-        memcpy(ul, ((UID){0x06,0x0E,0x2B,0x34,0x04,0x01,0x01,0x06,0x04,0x01,0x01,0x01,0x01,0x05,0x00,0x00}), 16);
-        return 0;
-    case AVCOL_TRC_LINEAR    :
-        memcpy(ul, ((UID){0x06,0x0E,0x2B,0x34,0x04,0x01,0x01,0x06,0x04,0x01,0x01,0x01,0x01,0x06,0x00,0x00}), 16);
-        return 0;
-    case AVCOL_TRC_SMPTE428  :
-        memcpy(ul, ((UID){0x06,0x0E,0x2B,0x34,0x04,0x01,0x01,0x08,0x04,0x01,0x01,0x01,0x01,0x07,0x00,0x00}), 16);
-        return 0;
-    default:
-        return -1;
-    }
-}
-
 static int64_t mxf_write_cdci_common(AVFormatContext *s, AVStream *st, const UID key)
 {
     MXFStreamContext *sc = st->priv_data;
@@ -1085,10 +1056,14 @@ static int64_t mxf_write_cdci_common(AVFormatContext *s, AVStream *st, const UID
     int stored_height = (st->codecpar->height+15)/16*16;
     int display_height;
     int f1, f2;
-    UID transfer_ul = {0};
+    const MXFCodecUL *color_primaries_ul;
+    const MXFCodecUL *color_trc_ul;
+    const MXFCodecUL *color_space_ul;
     int64_t pos = mxf_write_generic_desc(s, st, key);
 
-    get_trc(transfer_ul, st->codecpar->color_trc);
+    color_primaries_ul = mxf_get_codec_ul_by_id(ff_mxf_color_primaries_uls, st->codecpar->color_primaries);
+    color_trc_ul       = mxf_get_codec_ul_by_id(ff_mxf_color_trc_uls, st->codecpar->color_trc);
+    color_space_ul     = mxf_get_codec_ul_by_id(ff_mxf_color_space_uls, st->codecpar->color_space);
 
     if (st->codecpar->codec_id == AV_CODEC_ID_DVVIDEO) {
         if (st->codecpar->height == 1080)
@@ -1235,10 +1210,19 @@ static int64_t mxf_write_cdci_common(AVFormatContext *s, AVStream *st, const UID
     avio_wb32(pb, sc->aspect_ratio.num);
     avio_wb32(pb, sc->aspect_ratio.den);
 
-    //Transfer characteristic
-    if (transfer_ul[0]) {
+    if (color_primaries_ul->uid[0]) {
+        mxf_write_local_tag(pb, 16, 0x3219);
+        avio_write(pb, color_primaries_ul->uid, 16);
+    };
+
+    if (color_trc_ul->uid[0]) {
         mxf_write_local_tag(pb, 16, 0x3210);
-        avio_write(pb, transfer_ul, 16);
+        avio_write(pb, color_trc_ul->uid, 16);
+    };
+
+    if (color_space_ul->uid[0]) {
+        mxf_write_local_tag(pb, 16, 0x321A);
+        avio_write(pb, color_space_ul->uid, 16);
     };
 
     mxf_write_local_tag(pb, 16, 0x3201);
-- 
2.28.0