avformat/matroskaenc: write a CRC32 element on Chapters

Implements part of ticket #4347

Tested-by: Dave Rice <dave@dericed.com>
Tested-by: Jerome Martinez <jerome@mediaarea.net>
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: James Almer <jamrial@gmail.com>

libavformat/matroskaenc.c

@@ -1270,7 +1270,7 @@ static int mkv_write_tracks(AVFormatContext *s)
 static int mkv_write_chapters(AVFormatContext *s)
 {
     MatroskaMuxContext *mkv = s->priv_data;
-    AVIOContext *pb = s->pb;
+    AVIOContext *dyn_cp, *pb = s->pb;
     ebml_master chapters, editionentry;
     AVRational scale = {1, 1E9};
     int i, ret;
@@ -1281,10 +1281,12 @@ static int mkv_write_chapters(AVFormatContext *s)
     ret = mkv_add_seekhead_entry(mkv->main_seekhead, MATROSKA_ID_CHAPTERS, avio_tell(pb));
     if (ret < 0) return ret;
 
-    chapters     = start_ebml_master(pb, MATROSKA_ID_CHAPTERS    , 0);
-    editionentry = start_ebml_master(pb, MATROSKA_ID_EDITIONENTRY, 0);
-    put_ebml_uint(pb, MATROSKA_ID_EDITIONFLAGDEFAULT, 1);
-    put_ebml_uint(pb, MATROSKA_ID_EDITIONFLAGHIDDEN , 0);
+    ret = start_ebml_master_crc32(pb, &dyn_cp, &chapters, MATROSKA_ID_CHAPTERS, 0);
+    if (ret < 0) return ret;
+
+    editionentry = start_ebml_master(dyn_cp, MATROSKA_ID_EDITIONENTRY, 0);
+    put_ebml_uint(dyn_cp, MATROSKA_ID_EDITIONFLAGDEFAULT, 1);
+    put_ebml_uint(dyn_cp, MATROSKA_ID_EDITIONFLAGHIDDEN , 0);
     for (i = 0; i < s->nb_chapters; i++) {
         ebml_master chapteratom, chapterdisplay;
         AVChapter *c     = s->chapters[i];
@@ -1298,22 +1300,22 @@ static int mkv_write_chapters(AVFormatContext *s)
             return AVERROR_INVALIDDATA;
         }
 
-        chapteratom = start_ebml_master(pb, MATROSKA_ID_CHAPTERATOM, 0);
-        put_ebml_uint(pb, MATROSKA_ID_CHAPTERUID, c->id + mkv->chapter_id_offset);
-        put_ebml_uint(pb, MATROSKA_ID_CHAPTERTIMESTART, chapterstart);
-        put_ebml_uint(pb, MATROSKA_ID_CHAPTERTIMEEND, chapterend);
-        put_ebml_uint(pb, MATROSKA_ID_CHAPTERFLAGHIDDEN , 0);
-        put_ebml_uint(pb, MATROSKA_ID_CHAPTERFLAGENABLED, 1);
+        chapteratom = start_ebml_master(dyn_cp, MATROSKA_ID_CHAPTERATOM, 0);
+        put_ebml_uint(dyn_cp, MATROSKA_ID_CHAPTERUID, c->id + mkv->chapter_id_offset);
+        put_ebml_uint(dyn_cp, MATROSKA_ID_CHAPTERTIMESTART, chapterstart);
+        put_ebml_uint(dyn_cp, MATROSKA_ID_CHAPTERTIMEEND, chapterend);
+        put_ebml_uint(dyn_cp, MATROSKA_ID_CHAPTERFLAGHIDDEN , 0);
+        put_ebml_uint(dyn_cp, MATROSKA_ID_CHAPTERFLAGENABLED, 1);
         if ((t = av_dict_get(c->metadata, "title", NULL, 0))) {
-            chapterdisplay = start_ebml_master(pb, MATROSKA_ID_CHAPTERDISPLAY, 0);
-            put_ebml_string(pb, MATROSKA_ID_CHAPSTRING, t->value);
-            put_ebml_string(pb, MATROSKA_ID_CHAPLANG  , "und");
-            end_ebml_master(pb, chapterdisplay);
+            chapterdisplay = start_ebml_master(dyn_cp, MATROSKA_ID_CHAPTERDISPLAY, 0);
+            put_ebml_string(dyn_cp, MATROSKA_ID_CHAPSTRING, t->value);
+            put_ebml_string(dyn_cp, MATROSKA_ID_CHAPLANG  , "und");
+            end_ebml_master(dyn_cp, chapterdisplay);
         }
-        end_ebml_master(pb, chapteratom);
+        end_ebml_master(dyn_cp, chapteratom);
     }
-    end_ebml_master(pb, editionentry);
-    end_ebml_master(pb, chapters);
+    end_ebml_master(dyn_cp, editionentry);
+    end_ebml_master_crc32(pb, &dyn_cp, mkv, chapters);
 
     mkv->wrote_chapters = 1;
     return 0;