php-PHP实现视频上传与播放，代码出现问题，求解！上传图片后提示没有上传文件或文件大于300M，是什么原因？

视频php

session_start();
include "conn/conn.php";
//判断文件后缀
//$f_type：允许文件的后缀类型
//$f_upfiles：上传文件名
function f_postfix($f_type,$f_upfiles){
$is_pass = false;
$tmp_upfiles = split(".",$f_upfiles);
$tmp_num = count($tmp_upfiles);
for($num = 0; $num if(strtolower($tmp_upfiles[$tmp_num - 1]) == $f_type[$num])
$is_pass = $f_type[$num];
}
return $is_pass;
}
$p_type = array("jpg","jpeg","bmp","gif","png");
$f_type = array("avi","rm","rmvb","wav","mp3","mpg");
$video_path = "upfiles/video";
$picture_path =" ";
$file_path = "";
/* 判断上传图片类型和文件大小，上传图片 */
if($_FILES[tb_video_picture][size] > 0 and $_FILES[tb_video_picture][size] if(($postf = f_postfix($p_type,$_FILES[tb_video_picture][name])) != false){
$picture_path = time().".".$postf;
$tb_video_picture=$video_path."/".$picture_path;
if($_FILES[tb_video_picture][tmp_name])
move_uploaded_file($_FILES[tb_video_picture][tmp_name],$video_path."\".$picture_path);
else{
echo "alert('上传图片失败！');history.go(-1);";
exit();
}
}else{
echo "alert('上传图片格式错误！');history.go(-1);";
exit();
}
}else if($_FILES[tb_video_picture][size] > 700000){
echo "alert('上传图片大小超出范围！');history.go(-1);";
exit();
}else{
$picture = "";
}

/******************************//*  判断上传文件类型与大小，上传文件  */if($_FILES[tb_video_address][size] > 0){    //如果是音频文件        if($_FILES[tb_video_address][size] alert('上传文件错误！');history.go(-1);";                    exit();                }            }else{                echo "";                exit();            }        }else{            echo "";            exit();        }}/*else{    echo "";    exit();}*//****************//*  相同的信息  */$tb_video_name = $_POST[tb_video_name];                 //视频名称$tb_video_type = $_POST[tb_video_type];         $tb_video_explain = $_POST[tb_video_explain];$tb_video_author = $_POST[tb_video_author];$tb_video_date = date("Y-m-d H:i:s");/*****************/    $a_sqlstr = "insert into tb_video (tb_video_name,tb_video_picture,tb_video_type,tb_video_address,tb_video_author,tb_video_date,tb_video_explain,tb_video_auditing) values('$tb_video_name','$tb_video_picture','$tb_video_type','$tb_video_address','$tb_video_author','$tb_video_date','$tb_video_explain','0')";/***************************/$a_rst = $conn->execute($a_sqlstr);if(!($a_rst == false)){

$b_sqlstr="select * from tb_up_video where tb_video_user='$tb_video_author'";
$b_rst=$conn->execute($b_sqlstr);

$arrays=$b_rst->GetRows();
if(count($arrays)

$b1_sqlstr="insert into tb_up_video (tb_video_user,tb_up_counts)values('$tb_video_author','1')";
$b1_rst=$conn->execute($b1_sqlstr);

}else{
$b2_sqlstr="update tb_up_video set tb_up_counts=tb_up_counts+1 where tb_video_user='$tb_video_author'";
$b2_rst=$conn->execute($b2_sqlstr);
}

    echo "";

include_once("subscibe.php");
exit();
}else{
echo "alert('添加失败');history.go(-1);";
exit();
}
?>