put_be32(pb, 0);
if (track->mode == MODE_MOV) put_tag(pb, "mhlr");  else put_be32(pb, 0);
static int mov_write_hdlr_tag(ByteIOContext *pb, MOVTrack* track){    char *str;    int pos = url_ftell(pb);    put_be32(pb, 0); /* size */    put_tag(pb, "hdlr");    put_be32(pb, 0); /* Version & flags */    put_be32(pb, 0); /* reserved */    if(track->enc->codec_type == CODEC_TYPE_VIDEO)        put_tag(pb, "vide"); /* handler type */    else        put_tag(pb, "soun"); /* handler type */    put_be32(pb ,0); /* reserved */    put_be32(pb ,0); /* reserved */    put_be32(pb ,0); /* reserved */    if(track->enc->codec_type == CODEC_TYPE_VIDEO)        str = "VideoHandler";    else        str = "SoundHandler";    put_byte(pb, strlen(str)); /* string counter */    put_buffer(pb, str, strlen(str));    return updateSize(pb, pos);}