movenc: Allow override of major brand in ftyp atom

Signed-off-by: Tim Walker <tdskywalker@gmail.com>

libavformat/movenc.c

@@ -64,6 +64,7 @@ static const AVOption options[] = {
     { "min_frag_duration", "Minimum fragment duration", offsetof(MOVMuxContext, min_fragment_duration), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM},
     { "frag_size", "Maximum fragment size", offsetof(MOVMuxContext, max_fragment_size), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM},
     { "ism_lookahead", "Number of lookahead entries for ISM files", offsetof(MOVMuxContext, ism_lookahead), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM},
+    { "brand",    "Override major brand", offsetof(MOVMuxContext, major_brand),   AV_OPT_TYPE_STRING, {.str = NULL}, .flags = AV_OPT_FLAG_ENCODING_PARAM },
     { NULL },
 };
 
@@ -2564,7 +2565,9 @@ static int mov_write_ftyp_tag(AVIOContext *pb, AVFormatContext *s)
     avio_wb32(pb, 0); /* size */
     ffio_wfourcc(pb, "ftyp");
 
-    if (mov->mode == MODE_3GP) {
+    if (mov->major_brand && strlen(mov->major_brand) >= 4)
+        ffio_wfourcc(pb, mov->major_brand);
+    else if (mov->mode == MODE_3GP) {
         ffio_wfourcc(pb, has_h264 ? "3gp6"  : "3gp4");
         minor =     has_h264 ?   0x100 :   0x200;
     } else if (mov->mode & MODE_3G2) {

libavformat/movenc.h

@@ -159,6 +159,8 @@ typedef struct MOVMuxContext {
     AVIOContext *mdat_buf;
 
     int64_t reserved_moov_pos;
+
+    char *major_brand;
 } MOVMuxContext;
 
 #define FF_MOV_FLAG_RTP_HINT 1