@@ -44,6 +44,7 @@

 static const AVOption options[] = {

     { "movflags", "MOV muxer flags", offsetof(MOVMuxContext, flags), AV_OPT_TYPE_FLAGS, {.dbl = 0}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },

     { "rtphint", "Add RTP hint tracks", 0, AV_OPT_TYPE_CONST, {.dbl = FF_MOV_FLAG_RTP_HINT}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "movflags" },

+    { "moov_size", "maximum moov size so it can be placed at the begin", offsetof(MOVMuxContext, reserved_moov_size), AV_OPT_TYPE_INT, {.dbl = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, 0 },

     FF_RTP_FLAG_OPTS(MOVMuxContext, rtp_flags),

     { NULL },

 };

@@ -2274,6 +2275,11 @@ static int mov_write_header(AVFormatContext *s)

         av_set_pts_info(st, 64, 1, track->timescale);

     }

+    if(mov->reserved_moov_size){

+        mov->reserved_moov_pos= avio_tell(pb);

+        avio_skip(pb, mov->reserved_moov_size);

+    }

+

     mov_write_mdat_tag(pb, mov);

 #if FF_API_TIMESTAMP

@@ -2328,9 +2334,21 @@ static int mov_write_trailer(AVFormatContext *s)

         ffio_wfourcc(pb, "mdat");

         avio_wb64(pb, mov->mdat_size+16);

     }

-    avio_seek(pb, moov_pos, SEEK_SET);

+    avio_seek(pb, mov->reserved_moov_size ? mov->reserved_moov_pos : moov_pos, SEEK_SET);

     mov_write_moov_tag(pb, mov, s);

+    if(mov->reserved_moov_size){

+        int64_t size=  mov->reserved_moov_size - (avio_tell(pb) - mov->reserved_moov_pos);

+        if(size < 8){

+            av_log(s, AV_LOG_ERROR, "reserved_moov_size is too small, needed %Ld additional\n", 8-size);

+            return -1;

+        }

+        avio_wb32(pb, size);

+        ffio_wfourcc(pb, "free");

+        for(i=0; i<size; i++)

+            avio_w8(pb, 0);

+        avio_seek(pb, moov_pos, SEEK_SET);

+    }

     if (mov->chapter_track)

         av_freep(&mov->tracks[mov->chapter_track].enc);

@@ -112,6 +112,8 @@ typedef struct MOVMuxContext {

     int flags;

     int rtp_flags;

+    int reserved_moov_size;

+    int64_t reserved_moov_pos;

 } MOVMuxContext;

 #define FF_MOV_FLAG_RTP_HINT 1