From c2204c579c8411771b53a4bc66324c7c5d07698a Mon Sep 17 00:00:00 2001
From: John Stebbins <stebbins@jetheaddev.com>
Date: Thu, 16 Nov 2017 14:40:12 -0800
Subject: [PATCH] movenc: add sdtp (sample dependency) box to mp4

The AppleTV 4K requires this box in order to play 2160p60 video.
---
 libavcodec/avcodec.h |  9 +++++++--
 libavformat/movenc.c | 34 +++++++++++++++++++++++++++++++++-
 libavformat/movenc.h |  6 ++++++
 3 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 5624835023..48e9d23679 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -1161,8 +1161,13 @@ typedef struct AVPacket {
     int64_t convergence_duration;
 #endif
 } AVPacket;
-#define AV_PKT_FLAG_KEY     0x0001 ///< The packet contains a keyframe
-#define AV_PKT_FLAG_CORRUPT 0x0002 ///< The packet content is corrupted
+#define AV_PKT_FLAG_KEY         0x0001 ///< The packet contains a keyframe
+#define AV_PKT_FLAG_CORRUPT     0x0002 ///< The packet content is corrupted
+/**
+ * Flag is used to indicate packets that contain frames that can
+ * be discarded by the decoder.  I.e. Non-reference frames.
+ */
+#define AV_PKT_FLAG_DISPOSABLE  0x0004
 
 enum AVSideDataParamChangeFlags {
     AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_COUNT  = 0x0001,
diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index a546fdfead..d263f444f4 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -227,6 +227,30 @@ static int mov_write_stss_tag(AVIOContext *pb, MOVTrack *track, uint32_t flag)
     return update_size(pb, pos);
 }
 
+/* Sample dependency atom */
+static int mov_write_sdtp_tag(AVIOContext *pb, MOVTrack *track)
+{
+    int i;
+    uint8_t leading, dependent, reference, redundancy;
+    int64_t pos = avio_tell(pb);
+    avio_wb32(pb, 0); // size
+    ffio_wfourcc(pb, "sdtp");
+    avio_wb32(pb, 0); // version & flags
+    for (i = 0; i < track->entry; i++) {
+        dependent = MOV_SAMPLE_DEPENDENCY_YES;
+        leading = reference = redundancy = MOV_SAMPLE_DEPENDENCY_UNKNOWN;
+        if (track->cluster[i].flags & MOV_DISPOSABLE_SAMPLE) {
+            reference = MOV_SAMPLE_DEPENDENCY_NO;
+        }
+        if (track->cluster[i].flags & MOV_SYNC_SAMPLE) {
+            dependent = MOV_SAMPLE_DEPENDENCY_NO;
+        }
+        avio_w8(pb, (leading << 6)   | (dependent << 4) |
+                    (reference << 2) | redundancy);
+    }
+    return update_size(pb, pos);
+}
+
 static int mov_write_amr_tag(AVIOContext *pb, MOVTrack *track)
 {
     avio_wb32(pb, 0x11); /* size */
@@ -1211,8 +1235,12 @@ static int mov_write_stbl_tag(AVFormatContext *s, AVIOContext *pb, MOVTrack *tra
     mov_write_stts_tag(pb, track);
     if ((track->par->codec_type == AVMEDIA_TYPE_VIDEO ||
          track->par->codec_tag == MKTAG('r','t','p',' ')) &&
-        track->has_keyframes && track->has_keyframes < track->entry)
+        track->has_keyframes && track->has_keyframes < track->entry) {
         mov_write_stss_tag(pb, track, MOV_SYNC_SAMPLE);
+    }
+    if (track->par->codec_type == AVMEDIA_TYPE_VIDEO && track->has_disposable) {
+        mov_write_sdtp_tag(pb, track);
+    }
     if (track->mode == MODE_MOV && track->flags & MOV_TRACK_STPS)
         mov_write_stss_tag(pb, track, MOV_PARTIAL_SYNC_SAMPLE);
     if (track->par->codec_type == AVMEDIA_TYPE_VIDEO &&
@@ -3647,6 +3675,10 @@ int ff_mov_write_packet(AVFormatContext *s, AVPacket *pkt)
         if (trk->cluster[trk->entry].flags & MOV_SYNC_SAMPLE)
             trk->has_keyframes++;
     }
+    if (pkt->flags & AV_PKT_FLAG_DISPOSABLE) {
+        trk->cluster[trk->entry].flags |= MOV_DISPOSABLE_SAMPLE;
+        trk->has_disposable++;
+    }
     trk->entry++;
     trk->sample_count += samples_in_chunk;
     mov->mdat_size    += size;
diff --git a/libavformat/movenc.h b/libavformat/movenc.h
index 008f4671c6..f4eb4e8078 100644
--- a/libavformat/movenc.h
+++ b/libavformat/movenc.h
@@ -51,6 +51,7 @@ typedef struct MOVIentry {
     int          cts;
 #define MOV_SYNC_SAMPLE         0x0001
 #define MOV_PARTIAL_SYNC_SAMPLE 0x0002
+#define MOV_DISPOSABLE_SAMPLE   0x0004
     uint32_t     flags;
 } MOVIentry;
 
@@ -85,6 +86,7 @@ typedef struct MOVTrack {
     long        sample_count;
     long        sample_size;
     int         has_keyframes;
+    int         has_disposable;
 #define MOV_TRACK_CTTS         0x0001
 #define MOV_TRACK_STPS         0x0002
 #define MOV_TRACK_ENABLED      0x0004
@@ -180,6 +182,10 @@ typedef struct MOVMuxContext {
     int missing_duration_warned;
 } MOVMuxContext;
 
+#define MOV_SAMPLE_DEPENDENCY_UNKNOWN 0x0
+#define MOV_SAMPLE_DEPENDENCY_YES     0x1
+#define MOV_SAMPLE_DEPENDENCY_NO      0x2
+
 #define FF_MOV_FLAG_RTP_HINT              (1 <<  0)
 #define FF_MOV_FLAG_FRAGMENT              (1 <<  1)
 #define FF_MOV_FLAG_EMPTY_MOOV            (1 <<  2)
-- 
2.13.6