[FFmpeg-devel] [PATCH v3 1/2] avformat/mxf: set stream frame rates for ST 422 essence containers

[pal@sandflow.com]

From: Pierre-Anthony Lemieux <pal@palemieux.com>

The MXF demuxer does not currently set AVStream::avg_frame_rate and ::r_frame_rate
when J2K essence is wrapped according to SMPTE ST 422.

---
 libavformat/mxfdec.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
index feebff67aa..043e2e06ec 100644
--- a/libavformat/mxfdec.c
+++ b/libavformat/mxfdec.c
@@ -2140,6 +2140,13 @@ finish_decoding_index:
     return ret;
 }
 
+static int mxf_is_st_422(const UID *essence_container_ul) {
+    static const uint8_t st_422_essence_container_ul[] = { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x07,0x0d,0x01,0x03,0x01,0x02,0x0c };
+
+    return essence_container_ul && mxf_match_uid(*essence_container_ul, st_422_essence_container_ul,
+                                                 sizeof(st_422_essence_container_ul));
+}
+
 static int mxf_is_intra_only(MXFDescriptor *descriptor)
 {
     return mxf_get_codec_ul(mxf_intra_only_essence_container_uls,
@@ -2892,6 +2899,24 @@ static int mxf_parse_structural_metadata(MXFContext *mxf)
                     av_log(mxf->fc, AV_LOG_INFO, "Unknown frame layout type: %d\n", descriptor->frame_layout);
             }
 
+            if (mxf_is_st_422(essence_container_ul)) {
+                switch ((*essence_container_ul)[14]) {
+                case 2: /* Cn: Clip- wrapped Picture Element */
+                case 3: /* I1: Interlaced Frame, 1 field/KLV */
+                case 4: /* I2: Interlaced Frame, 2 fields/KLV */
+                case 6: /* P1: Frame- wrapped Picture Element */
+                    st->avg_frame_rate = source_track->edit_rate;
+                    st->r_frame_rate = st->avg_frame_rate;
+                    break;
+                case 5: /* F1: Field-wrapped Picture Element */
+                    st->avg_frame_rate = av_mul_q(av_make_q(2, 1), source_track->edit_rate);
+                    st->r_frame_rate = st->avg_frame_rate;
+                    break;
+                default:
+                    break;
+                }
+            }
+
             if (st->codecpar->codec_id == AV_CODEC_ID_PRORES) {
                 switch (descriptor->essence_codec_ul[14]) {
                 case 1: st->codecpar->codec_tag = MKTAG('a','p','c','o'); break;
-- 
2.25.1

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