欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页  >  IT编程

c#实现flv解析详解示例

程序员文章站 2024-02-24 22:46:58
先上效果图:   工具类 在解析的过程中,我们会和byte做各种运算,所以我定义了一个byte工具类byteutils: 复制代码...

先上效果图:

c#实现flv解析详解示例
 
工具类

在解析的过程中,我们会和byte做各种运算,所以我定义了一个byte工具类byteutils:

复制代码 代码如下:

using system;
using system.collections.generic;
using system.linq;
using system.text;
using system.io;

namespace flvparer.utils
{
    class byteutils
    {
        public static uint bytetouint(byte[] bs, int length)
        {
            if (bs == null || bs.length < length)
                return 0;
            uint rtn = 0;
            for (int i = 0; i < length; i++)
            {
                rtn <<= 8;
                rtn |= bs[i];
            }
            return rtn;
        }
        public static double bytetodouble(byte[] bs)
        {
            if (bs == null || bs.length < 8)
                return 0;
            byte[] b2 = new byte[8];
            for (int i = 0; i < 8; i++)
            {
                b2[i] = bs[7 - i];
            }
            return bitconverter.todouble(b2, 0);
        }
        public static short readui16(stream src)
        {
            byte[] bs = new byte[2];
            if (src.read(bs, 0, 2) <= 0)
                return 0;
            return (short)((bs[0] << 8) | bs[1]);
        }
        public static uint readui24(stream src)
        {
            byte[] bs = new byte[3];
            if (src.read(bs, 0, 3) <= 0)
                throw new ioexception("stream end.");
            return bytetouint(bs, 3);
        }
        public static uint readui32(stream src)
        {
            byte[] bs = new byte[4];
            if (src.read(bs, 0, 4) <= 0)
                throw new ioexception("stream end.");
            return bytetouint(bs, 4);
        }
        public static string gettime(uint time)
        {
            return (time / 60000).tostring() + ":"
                + (time / 1000 % 60).tostring("d2") + "."
                + (time % 1000).tostring("d3");
        }
    }
}

flv类

flv类,主要的类,里面包括一个header和许多的tag,也就是一个flv文件的结构:

复制代码 代码如下:

using system;
using system.collections.generic;
using system.linq;
using system.text;
using system.io;
using flvparer.utils;

namespace flvparer.model
{
    class flv
    {
        public header header { get; private set; }
        list<tag> tags;
        public flv(stream stream)
        {
            header = new header();
            header.readheader(stream);
            stream.seek(header.size, seekorigin.begin);
            tags = new list<tag>();
            while (stream.position < stream.length-4)
            {
                tags.add(readtag(stream));               
            }

        }

        private tag readtag(stream stream)
        {
            tag tag = null;
            byte[] buf = new byte[4];
            stream.read(buf, 0, 4);
            int type = stream.readbyte();
            switch (type)
            {
                case 8:
                    tag = new audiotag();
                    break;
                case 9:
                    tag = new videotag();
                    break;
                case 18:
                    tag = new scripttag();
                    break;
            }
            tag.presize = byteutils.bytetouint(buf, 4);
            tag.datasize = byteutils.readui24(stream);
            tag.timestamp = byteutils.readui24(stream);
            tag.timestamp_ex = stream.readbyte();
            tag.streamid = byteutils.readui24(stream);           
            tag.readdata(stream);          
            return tag;
        }
    }
}

header类

header类,保存flv文件的头信息:

复制代码 代码如下:

using system;
using system.collections.generic;
using system.linq;
using system.text;
using system.io;
using flvparer.utils;

namespace flvparer.model
{
    class header
    {
        public string type { get; private set; }
        public int version { get; private set; }
        public bool hasvideo { get; private set; }
        public bool hasaudio { get; private set; }
        public uint size { get; private set; }

        public void readheader(stream stream)
        {
            byte[] buf = new byte[4];
            stream.read(buf, 0, 3);
            type = encoding.default.getstring(buf);
            stream.read(buf, 0, 1);
            version = buf[0];
            stream.read(buf, 0, 1);
            buf[0] &= 0x0f;
            if ((buf[0] & 0x01) == 1)
            {
                hasvideo = true;
            }
            if ((buf[0] & 0x04) == 4)
            {
                hasaudio = true;
            }
            stream.read(buf, 0, 4);
            size = byteutils.bytetouint(buf, 4);
        }
    }
}

tag类

tag类是一个抽象类,因为tag的种类有三种,为了统一管理,抽象出tag类:

复制代码 代码如下:

using system;
using system.collections.generic;
using system.linq;
using system.text;
using system.io;

namespace flvparer.model
{
    enum tagtype
    {
        video,
        audio,
        script
    }
    abstract class tag
    {
        public tagtype tagtype;//tag类型
        public uint presize;//前一tag大小
        public uint datasize;//数据区大小
        public uint timestamp; //时间戳 单位ms
        public int timestamp_ex;//时间戳扩展
        public uint streamid;//id
        public long offset;//偏移量
        public byte[] data;//数据
        //对tag进行读取
        public abstract void readdata(stream stream);
    }
}

scripttag类

脚本tag类,继承自tag类,并添加成员变量values,用于保存脚本信息:

复制代码 代码如下:

using system.collections.generic;
using system.text;
using system.io;
using flvparer.utils;

namespace flvparer.model
{
    class scripttag : tag
    {
        public list<keyvaluepair<string, object>> values { get; private set; }
        public scripttag()
        {
            tagtype = tagtype.script;
            values = new list<keyvaluepair<string, object>>();
        }

        public override void readdata(stream stream)
        {
            offset = 0;
            values.clear();
            byte[] bs = new byte[3];
            while (offset < this.datasize)
            {
                stream.read(bs, 0, 3);
                if (bs[0] == 0 && bs[1] == 0 && bs[2] == 9)
                {
                    offset += 3;
                    break;
                }
                stream.seek(-3, seekorigin.current);
                addelement("#" + offset, readelement(stream));
            }
        }

        private void addelement(string key, object o)
        {
            values.add(new keyvaluepair<string, object>(key, o));
        }

        private object readelement(stream src)
        {
            int type = src.readbyte();
            offset++;
            switch (type)
            {
                case 0: // number - 8
                    return readdouble(src);
                case 1: // boolean - 1
                    return readbyte(src);
                case 2: // string - 2+n
                    return readstring(src);
                case 3: // object
                    return readobject(src);
                case 4: // movieclip
                    return readstring(src);
                case 5: // null
                    break;
                case 6: // undefined
                    break;
                case 7: // reference - 2
                    return readushort(src);
                case 8: // ecma array
                    return readarray(src);
                case 10: // strict array
                    return readstrictarray(src);
                case 11: // date - 8+2
                    return readdate(src);
                case 12: // long string - 4+n
                    return readlongstring(src);
            }
            return null;
        }
        private object readobject(stream src)
        {
            byte[] bs = new byte[3];
            scriptobject obj = new scriptobject();
            while (offset < this.datasize)
            {
                src.read(bs, 0, 3);
                if (bs[0] == 0 && bs[1] == 0 && bs[2] == 9)
                {
                    offset += 3;
                    break;
                }
                src.seek(-3, seekorigin.current);
                string key = readstring(src);
                if (key[0] == 0)
                    break;
                obj[key] = readelement(src);
            }
            return obj;
        }
        private double readdate(stream src)
        {
            double d = readdouble(src);
            src.seek(2, seekorigin.current);
            offset += 2;
            return d;
        }
        private scriptobject readarray(stream src)
        {
            byte[] buffer = new byte[4];
            src.read(buffer, 0, 4);
            offset += 4;
            uint count = byteutils.bytetouint(buffer, 4);
            scriptobject array = new scriptobject();
            for (uint i = 0; i < count; i++)
            {
                string key = readstring(src);
                array[key] = readelement(src);
            }
            src.seek(3, seekorigin.current); // 00 00 09
            offset += 3;
            return array;
        }
        private scriptarray readstrictarray(stream src)
        {
            byte[] bs = new byte[4];
            src.read(bs, 0, 4);
            offset += 4;
            scriptarray array = new scriptarray();
            uint count = byteutils.bytetouint(bs, 4);
            for (uint i = 0; i < count; i++)
            {
                array.add(readelement(src));
            }
            return array;
        }
        private double readdouble(stream src)
        {
            byte[] buffer = new byte[8];
            src.read(buffer, 0, 8);
            offset += 8;
            return byteutils.bytetodouble(buffer);
        }
        private byte readbyte(stream src)
        {
            offset++;
            return (byte)src.readbyte();
        }
        private string readstring(stream src)
        {
            byte[] bs = new byte[2];
            src.read(bs, 0, 2);
            offset += 2;
            int n = (int)byteutils.bytetouint(bs, 2);
            bs = new byte[n];
            src.read(bs, 0, n);
            offset += n;
            return encoding.ascii.getstring(bs);
        }
        private string readlongstring(stream src)
        {
            byte[] bs = new byte[4];
            src.read(bs, 0, 4);
            offset += 4;
            int n = (int)byteutils.bytetouint(bs, 4);
            bs = new byte[n];
            src.read(bs, 0, n);
            offset += n;
            return encoding.ascii.getstring(bs);
        }
        private ushort readushort(stream src)
        {
            byte[] buffer = new byte[2];
            src.read(buffer, 0, 2);
            offset += 2;
            return (ushort)byteutils.bytetouint(buffer, 2);
        }
    }

    public class scriptobject
    {
        public static int indent = 0;
        private dictionary<string, object> values = new dictionary<string, object>();
        public object this[string key]
        {
            get
            {
                object o;
                values.trygetvalue(key, out o);
                return o;
            }
            set
            {
                if (!values.containskey(key))
                {
                    values.add(key, value);
                }
            }
        }
        public override string tostring()
        {
            string str = "{\r\n";
            scriptobject.indent += 2;
            foreach (keyvaluepair<string, object> kv in values)
            {
                str += new string(' ', scriptobject.indent)
                          + kv.key + ": " + kv.value + "\r\n";
            }
            scriptobject.indent -= 2;
            //if (str.length > 1)
            //    str = str.substring(0, str.length - 1);
            str += "}";
            return str;
        }
    }
    public class scriptarray
    {
        private list<object> values = new list<object>();
        public object this[int index]
        {
            get
            {
                if (index >= 0 && index < values.count)
                    return values[index];
                return null;
            }
        }
        public void add(object o)
        {
            values.add(o);
        }
        public override string tostring()
        {
            string str = "[";
            int n = 0;
            foreach (object o in values)
            {
                if (n % 10 == 0)
                    str += "\r\n";
                n++;
                str += o + ",";
            }
            if (str.length > 1)
                str = str.substring(0, str.length - 1);
            str += "\r\n]";
            return str;
        }
    }
}

videotag类

视频tag类:

复制代码 代码如下:

using system.io;

namespace flvparer.model
{
    class videotag : tag
    {
        public int frametype;//帧类型
        public int encodeid;//编码id
        public videotag()
        {
            tagtype = tagtype.video;
        }
        public override void readdata(stream stream)
        {
            int info = stream.readbyte();
            frametype = info >> 4;
            encodeid = info & 0x0f;
            data = new byte[datasize - 1];
            stream.read(data, 0, (int)datasize - 1);
        }
    }
}

audiotag 类
音频tag类:

复制代码 代码如下:

using system.io;

namespace flvparer.model
{
    class audiotag : tag
    {
        public int formate;//音频格式
        public int rate;//采样率
        public int size;//采样的长度
        public int type;//音频类型
        public audiotag()
        {
            tagtype = tagtype.audio;
        }

        public override void readdata(stream stream)
        {
            int info = stream.readbyte();
            formate = info >> 4;
            rate = (info & 0x0c) >> 2;
            size = (info & 0x02) >> 1;
            type = info & 0x01;
            data = new byte[datasize - 1];
            stream.read(data, 0, (int)datasize - 1);
        }
    }
}

使用方法

用法很简单,new出来的时候把flv文件的stream对象传进去就行了,比如我这样的:

复制代码 代码如下:

flv flv = null;
using (filestream fs = new filestream("t31_stract.flv", filemode.open, fileaccess.read))
{
    flv = new flv(fs);
}

之后就可以使用flv对象来分析当前flv的信息了。