From 0da0acdae8e729eecfb2498ac11cb86a7fe3360d Mon Sep 17 00:00:00 2001
From: rcombs <rcombs@rcombs.me>
Date: Sat, 28 Jan 2023 14:19:17 -0600
Subject: [PATCH] demux_mkv: support ARIB captions

---
 demux/demux_mkv.c | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/demux/demux_mkv.c b/demux/demux_mkv.c
index 3f0472dae9..c330709d23 100644
--- a/demux/demux_mkv.c
+++ b/demux/demux_mkv.c
@@ -1831,9 +1831,15 @@ static const char *const mkv_sub_tag[][2] = {
     { "D_WEBVTT/CAPTIONS",  "webvtt-webm"},
     { "S_TEXT/WEBVTT",      "webvtt"},
     { "S_DVBSUB",           "dvb_subtitle"},
+    { "S_ARIBSUB",          "arib_caption"},
     {0}
 };
 
+static void avcodec_par_destructor(void *p)
+{
+    avcodec_parameters_free(p);
+}
+
 static int demux_mkv_open_sub(demuxer_t *demuxer, mkv_track_t *track)
 {
     const char *subtitle_type = NULL;
@@ -1862,6 +1868,38 @@ static int demux_mkv_open_sub(demuxer_t *demuxer, mkv_track_t *track)
     sh->codec->extradata = track->private_data;
     sh->codec->extradata_size = track->private_size;
 
+    if (!strcmp(sh->codec->codec, "arib_caption") && track->private_size >= 3) {
+        struct AVCodecParameters **lavp = talloc_ptrtype(track, lavp);
+
+        talloc_set_destructor(lavp, avcodec_par_destructor);
+
+        struct AVCodecParameters *lav = *lavp = sh->codec->lav_codecpar = avcodec_parameters_alloc();
+        MP_HANDLE_OOM(lav);
+
+        lav->codec_type = AVMEDIA_TYPE_SUBTITLE;
+        lav->codec_id = AV_CODEC_ID_ARIB_CAPTION;
+
+        int component_tag = track->private_data[0];
+        int data_component_id = AV_RB16(track->private_data + 1);
+        switch (data_component_id) {
+        case 0x0008:
+            // [0x30..0x37] are component tags utilized for
+            // non-mobile captioning service ("profile A").
+            if (component_tag >= 0x30 && component_tag <= 0x37)
+                lav->profile = FF_PROFILE_ARIB_PROFILE_A;
+            break;
+        case 0x0012:
+            // component tag 0x87 signifies a mobile/partial reception
+            // (1seg) captioning service ("profile C").
+            if (component_tag == 0x87)
+                lav->profile = FF_PROFILE_ARIB_PROFILE_C;
+            break;
+        }
+        if (lav->profile == FF_PROFILE_UNKNOWN)
+            MP_WARN(demuxer, "ARIB caption profile %02x / %04x not supported.\n",
+                    component_tag, data_component_id);
+    }
+
     demux_add_sh_stream(demuxer, sh);
 
     if (!subtitle_type)