add flv injecter, add flv codec to librtmp.

trunk/src/kernel/srs_kernel_error.hpp

@@ -118,6 +118,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 #define ERROR_SYSTEM_FILE_RENAME            429
 #define ERROR_SYSTEM_CREATE_PIPE            430
 #define ERROR_SYSTEM_FILE_SEEK              431
+#define ERROR_SYSTEM_FLV_HEADER             432
 
 // see librtmp.
 // failed when open ssl create the dh

trunk/src/kernel/srs_kernel_flv.cpp

@@ -0,0 +1,612 @@
+/*
+The MIT License (MIT)
+
+Copyright (c) 2013-2014 winlin
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+#include <srs_kernel_flv.hpp>
+
+#include <fcntl.h>
+#include <sstream>
+using namespace std;
+
+#include <srs_kernel_log.hpp>
+#include <srs_kernel_error.hpp>
+#include <srs_core_autofree.hpp>
+#include <srs_kernel_stream.hpp>
+#include <srs_kernel_utility.hpp>
+
+#define SRS_FLV_TAG_HEADER_SIZE 11
+#define SRS_FLV_PREVIOUS_TAG_SIZE 4
+
+SrsFileStream::SrsFileStream()
+{
+    fd = -1;
+}
+
+SrsFileStream::~SrsFileStream()
+{
+    close();
+}
+
+int SrsFileStream::open_write(string file)
+{
+    int ret = ERROR_SUCCESS;
+    
+    if (fd > 0) {
+        ret = ERROR_SYSTEM_FILE_ALREADY_OPENED;
+        srs_error("file %s already opened. ret=%d", _file.c_str(), ret);
+        return ret;
+    }
+    
+    int flags = O_CREAT|O_WRONLY|O_TRUNC;
+    mode_t mode = S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH;
+
+    if ((fd = ::open(file.c_str(), flags, mode)) < 0) {
+        ret = ERROR_SYSTEM_FILE_OPENE;
+        srs_error("open file %s failed. ret=%d", file.c_str(), ret);
+        return ret;
+    }
+    
+    _file = file;
+    
+    return ret;
+}
+
+int SrsFileStream::open_read(string file)
+{
+    int ret = ERROR_SUCCESS;
+    
+    if (fd > 0) {
+        ret = ERROR_SYSTEM_FILE_ALREADY_OPENED;
+        srs_error("file %s already opened. ret=%d", _file.c_str(), ret);
+        return ret;
+    }
+
+    if ((fd = ::open(file.c_str(), O_RDONLY)) < 0) {
+        ret = ERROR_SYSTEM_FILE_OPENE;
+        srs_error("open file %s failed. ret=%d", file.c_str(), ret);
+        return ret;
+    }
+    
+    _file = file;
+    
+    return ret;
+}
+
+void SrsFileStream::close()
+{
+    int ret = ERROR_SUCCESS;
+    
+    if (fd < 0) {
+        return;
+    }
+    
+    if (::close(fd) < 0) {
+        ret = ERROR_SYSTEM_FILE_CLOSE;
+        srs_error("close file %s failed. ret=%d", _file.c_str(), ret);
+        return;
+    }
+    fd = -1;
+    
+    return;
+}
+
+bool SrsFileStream::is_open()
+{
+    return fd > 0;
+}
+
+int SrsFileStream::read(void* buf, size_t count, ssize_t* pnread)
+{
+    int ret = ERROR_SUCCESS;
+    
+    ssize_t nread;
+    if ((nread = ::read(fd, buf, count)) < 0) {
+        ret = ERROR_SYSTEM_FILE_READ;
+        srs_error("read from file %s failed. ret=%d", _file.c_str(), ret);
+        return ret;
+    }
+    
+    if (nread == 0) {
+        ret = ERROR_SYSTEM_FILE_EOF;
+        return ret;
+    }
+    
+    if (pnread != NULL) {
+        *pnread = nread;
+    }
+    
+    return ret;
+}
+
+int SrsFileStream::write(void* buf, size_t count, ssize_t* pnwrite)
+{
+    int ret = ERROR_SUCCESS;
+    
+    ssize_t nwrite;
+    if ((nwrite = ::write(fd, buf, count)) < 0) {
+        ret = ERROR_SYSTEM_FILE_WRITE;
+        srs_error("write to file %s failed. ret=%d", _file.c_str(), ret);
+        return ret;
+    }
+    
+    if (pnwrite != NULL) {
+        *pnwrite = nwrite;
+    }
+    
+    return ret;
+}
+
+int64_t SrsFileStream::tellg()
+{
+    return (int64_t)::lseek(fd, 0, SEEK_CUR);
+}
+
+int64_t SrsFileStream::lseek(int64_t offset)
+{
+    return (int64_t)::lseek(fd, offset, SEEK_SET);
+}
+
+int64_t SrsFileStream::filesize()
+{
+    int64_t cur = tellg();
+    int64_t size = (int64_t)::lseek(fd, 0, SEEK_END);
+    ::lseek(fd, cur, SEEK_SET);
+    return size;
+}
+
+void SrsFileStream::skip(int64_t size)
+{
+    ::lseek(fd, size, SEEK_CUR);
+}
+
+SrsFlvEncoder::SrsFlvEncoder()
+{
+    _fs = NULL;
+    tag_stream = new SrsStream();
+}
+
+SrsFlvEncoder::~SrsFlvEncoder()
+{
+    srs_freep(tag_stream);
+}
+
+int SrsFlvEncoder::initialize(SrsFileStream* fs)
+{
+    int ret = ERROR_SUCCESS;
+    
+    _fs = fs;
+    
+    return ret;
+}
+
+int SrsFlvEncoder::write_header()
+{
+    int ret = ERROR_SUCCESS;
+    
+    // 9bytes header and 4bytes first previous-tag-size
+    static char flv_header[] = {
+        'F', 'L', 'V', // Signatures "FLV"
+        (char)0x01, // File version (for example, 0x01 for FLV version 1)
+        (char)0x00, // 4, audio; 1, video; 5 audio+video.
+        (char)0x00, (char)0x00, (char)0x00, (char)0x09, // DataOffset UI32 The length of this header in bytes
+        (char)0x00, (char)0x00, (char)0x00, (char)0x00// PreviousTagSize0 UI32 Always 0
+    };
+    
+    // flv specification should set the audio and video flag,
+    // actually in practise, application generally ignore this flag,
+    // so we generally set the audio/video to 0.
+    
+    // write data.
+    if ((ret = _fs->write(flv_header, sizeof(flv_header), NULL)) != ERROR_SUCCESS) {
+        srs_error("write flv header failed. ret=%d", ret);
+        return ret;
+    }
+    
+    return ret;
+}
+
+int SrsFlvEncoder::write_metadata(char* data, int size)
+{
+    int ret = ERROR_SUCCESS;
+    
+    static char tag_header[] = {
+        (char)18, // TagType UB [5], 18 = script data
+        (char)0x00, (char)0x00, (char)0x00, // DataSize UI24 Length of the message.
+        (char)0x00, (char)0x00, (char)0x00, // Timestamp UI24 Time in milliseconds at which the data in this tag applies.
+        (char)0x00, // TimestampExtended UI8
+        (char)0x00, (char)0x00, (char)0x00, // StreamID UI24 Always 0.
+    };
+    
+    // write data size.
+    if ((ret = tag_stream->initialize(tag_header + 1, 3)) != ERROR_SUCCESS) {
+        return ret;
+    }
+    tag_stream->write_3bytes(size);
+    
+    if ((ret = write_tag(tag_header, sizeof(tag_header), data, size)) != ERROR_SUCCESS) {
+        srs_error("write flv data tag failed. ret=%d", ret);
+        return ret;
+    }
+    
+    return ret;
+}
+
+int SrsFlvEncoder::write_audio(int64_t timestamp, char* data, int size)
+{
+    int ret = ERROR_SUCCESS;
+    
+    timestamp &= 0x7fffffff;
+    
+    // 11bytes tag header
+    static char tag_header[] = {
+        (char)8, // TagType UB [5], 8 = audio
+        (char)0x00, (char)0x00, (char)0x00, // DataSize UI24 Length of the message.
+        (char)0x00, (char)0x00, (char)0x00, // Timestamp UI24 Time in milliseconds at which the data in this tag applies.
+        (char)0x00, // TimestampExtended UI8
+        (char)0x00, (char)0x00, (char)0x00, // StreamID UI24 Always 0.
+    };
+    
+    // write data size.
+    if ((ret = tag_stream->initialize(tag_header + 1, 7)) != ERROR_SUCCESS) {
+        return ret;
+    }
+    tag_stream->write_3bytes(size);
+    tag_stream->write_3bytes(timestamp);
+    // default to little-endian
+    tag_stream->write_1bytes((timestamp >> 24) & 0xFF);
+    
+    if ((ret = write_tag(tag_header, sizeof(tag_header), data, size)) != ERROR_SUCCESS) {
+        srs_error("write flv audio tag failed. ret=%d", ret);
+        return ret;
+    }
+    
+    return ret;
+}
+
+int SrsFlvEncoder::write_video(int64_t timestamp, char* data, int size)
+{
+    int ret = ERROR_SUCCESS;
+    
+    timestamp &= 0x7fffffff;
+    
+    // 11bytes tag header
+    static char tag_header[] = {
+        (char)9, // TagType UB [5], 9 = video
+        (char)0x00, (char)0x00, (char)0x00, // DataSize UI24 Length of the message.
+        (char)0x00, (char)0x00, (char)0x00, // Timestamp UI24 Time in milliseconds at which the data in this tag applies.
+        (char)0x00, // TimestampExtended UI8
+        (char)0x00, (char)0x00, (char)0x00, // StreamID UI24 Always 0.
+    };
+    
+    // write data size.
+    if ((ret = tag_stream->initialize(tag_header + 1, 7)) != ERROR_SUCCESS) {
+        return ret;
+    }
+    tag_stream->write_3bytes(size);
+    tag_stream->write_3bytes(timestamp);
+    // default to little-endian
+    tag_stream->write_1bytes((timestamp >> 24) & 0xFF);
+    
+    if ((ret = write_tag(tag_header, sizeof(tag_header), data, size)) != ERROR_SUCCESS) {
+        srs_error("write flv video tag failed. ret=%d", ret);
+        return ret;
+    }
+    
+    return ret;
+}
+
+int SrsFlvEncoder::write_tag(char* header, int header_size, char* tag, int tag_size)
+{
+    int ret = ERROR_SUCCESS;
+    
+    // write tag header.
+    if ((ret = _fs->write(header, header_size, NULL)) != ERROR_SUCCESS) {
+        srs_error("write flv tag header failed. ret=%d", ret);
+        return ret;
+    }
+    
+    // write tag data.
+    if ((ret = _fs->write(tag, tag_size, NULL)) != ERROR_SUCCESS) {
+        srs_error("write flv tag failed. ret=%d", ret);
+        return ret;
+    }
+    
+    // PreviousTagSizeN UI32 Size of last tag, including its header, in bytes.
+    static char pre_size[SRS_FLV_PREVIOUS_TAG_SIZE];
+    if ((ret = tag_stream->initialize(pre_size, SRS_FLV_PREVIOUS_TAG_SIZE)) != ERROR_SUCCESS) {
+        return ret;
+    }
+    tag_stream->write_4bytes(tag_size + header_size);
+    if ((ret = _fs->write(pre_size, sizeof(pre_size), NULL)) != ERROR_SUCCESS) {
+        srs_error("write flv previous tag size failed. ret=%d", ret);
+        return ret;
+    }
+    
+    return ret;
+}
+
+SrsFlvFastDecoder::SrsFlvFastDecoder()
+{
+    _fs = NULL;
+    tag_stream = new SrsStream();
+}
+
+SrsFlvFastDecoder::~SrsFlvFastDecoder()
+{
+    srs_freep(tag_stream);
+}
+
+int SrsFlvFastDecoder::initialize(SrsFileStream* fs)
+{
+    int ret = ERROR_SUCCESS;
+    
+    _fs = fs;
+    
+    return ret;
+}
+
+int SrsFlvFastDecoder::read_header(char** pdata, int* psize)
+{
+    *pdata = NULL;
+    *psize = 0;
+    
+    int ret = ERROR_SUCCESS;
+
+    srs_assert(_fs);
+    
+    // 9bytes header and 4bytes first previous-tag-size
+    int size = 13;
+    char* buf = new char[size];
+    
+    if ((ret = _fs->read(buf, size, NULL)) != ERROR_SUCCESS) {
+        return ret;
+    }
+    
+    *pdata = buf;
+    *psize = size;
+    
+    return ret;
+}
+
+int SrsFlvFastDecoder::read_sequence_header(int64_t* pstart, int* psize)
+{
+    *pstart = 0;
+    *psize = 0;
+    
+    int ret = ERROR_SUCCESS;
+
+    srs_assert(_fs);
+    
+    // simply, the first video/audio must be the sequence header.
+    // and must be a sequence video and audio.
+    
+    // 11bytes tag header
+    static char tag_header[] = {
+        (char)0x00, // TagType UB [5], 9 = video, 8 = audio, 18 = script data
+        (char)0x00, (char)0x00, (char)0x00, // DataSize UI24 Length of the message.
+        (char)0x00, (char)0x00, (char)0x00, // Timestamp UI24 Time in milliseconds at which the data in this tag applies.
+        (char)0x00, // TimestampExtended UI8
+        (char)0x00, (char)0x00, (char)0x00, // StreamID UI24 Always 0.
+    };
+    
+    // discovery the sequence header video and audio.
+    // @remark, maybe no video or no audio.
+    bool got_video = false;
+    bool got_audio = false;
+    // audio/video sequence and data offset.
+    int64_t av_sequence_offset_start = -1;
+    int64_t av_sequence_offset_end = -1;
+    for (;;) {
+        if ((ret = _fs->read(tag_header, SRS_FLV_TAG_HEADER_SIZE, NULL)) != ERROR_SUCCESS) {
+            return ret;
+        }
+        
+        if ((ret = tag_stream->initialize(tag_header, SRS_FLV_TAG_HEADER_SIZE)) != ERROR_SUCCESS) {
+            return ret;
+        }
+        
+        int8_t tag_type = tag_stream->read_1bytes();
+        int32_t data_size = tag_stream->read_3bytes();
+        
+        bool is_video = tag_type == 0x09;
+        bool is_audio = tag_type == 0x08;
+        bool is_not_av = !is_video && !is_audio;
+        if (is_not_av) {
+            // skip body and tag size.
+            _fs->skip(data_size + SRS_FLV_PREVIOUS_TAG_SIZE);
+            continue;
+        }
+        
+        // if video duplicated, no audio
+        if (is_video && got_video) {
+            break;
+        }
+        // if audio duplicated, no video
+        if (is_audio && got_audio) {
+            break;
+        }
+        
+        // video
+        if (is_video) {
+            srs_assert(!got_video);
+            got_video = true;
+            
+            if (av_sequence_offset_start < 0) {
+                av_sequence_offset_start = _fs->tellg() - SRS_FLV_TAG_HEADER_SIZE;
+            }
+            av_sequence_offset_end = _fs->tellg() + data_size + SRS_FLV_PREVIOUS_TAG_SIZE;
+            _fs->skip(data_size + SRS_FLV_PREVIOUS_TAG_SIZE);
+        }
+        
+        // audio
+        if (is_audio) {
+            srs_assert(!got_audio);
+            got_audio = true;
+            
+            if (av_sequence_offset_start < 0) {
+                av_sequence_offset_start = _fs->tellg() - SRS_FLV_TAG_HEADER_SIZE;
+            }
+            av_sequence_offset_end = _fs->tellg() + data_size + SRS_FLV_PREVIOUS_TAG_SIZE;
+            _fs->skip(data_size + SRS_FLV_PREVIOUS_TAG_SIZE);
+        }
+    }
+    
+    // seek to the sequence header start offset.
+    if (av_sequence_offset_start > 0) {
+        _fs->lseek(av_sequence_offset_start);
+        *pstart = av_sequence_offset_start;
+        *psize = (int)(av_sequence_offset_end - av_sequence_offset_start);
+    }
+    
+    return ret;
+}
+
+int SrsFlvFastDecoder::lseek(int64_t offset)
+{
+    int ret = ERROR_SUCCESS;
+
+    srs_assert(_fs);
+    
+    if (offset >= _fs->filesize()) {
+        ret = ERROR_SYSTEM_FILE_EOF;
+        srs_warn("flv fast decoder seek overflow file, "
+            "size=%"PRId64", offset=%"PRId64", ret=%d", 
+            _fs->filesize(), offset, ret);
+        return ret;
+    }
+    
+    if (_fs->lseek(offset) < 0) {
+        ret = ERROR_SYSTEM_FILE_SEEK;
+        srs_warn("flv fast decoder seek error, "
+            "size=%"PRId64", offset=%"PRId64", ret=%d", 
+            _fs->filesize(), offset, ret);
+        return ret;
+    }
+    
+    return ret;
+}
+
+SrsFlvDecoder::SrsFlvDecoder()
+{
+    _fs = NULL;
+    tag_stream = new SrsStream();
+}
+
+SrsFlvDecoder::~SrsFlvDecoder()
+{
+    srs_freep(tag_stream);
+}
+
+int SrsFlvDecoder::initialize(SrsFileStream* fs)
+{
+    int ret = ERROR_SUCCESS;
+    
+    _fs = fs;
+    
+    return ret;
+}
+
+int SrsFlvDecoder::read_header(char header[9])
+{
+    int ret = ERROR_SUCCESS;
+
+    if ((ret = _fs->read(header, 9, NULL)) != ERROR_SUCCESS) {
+        return ret;
+    }
+    
+    char* h = header;
+    if (h[0] != 'F' || h[1] != 'L' || h[2] != 'V') {
+        ret = ERROR_SYSTEM_FLV_HEADER;
+        srs_warn("flv header must start with FLV. ret=%d", ret);
+        return ret;
+    }
+    
+    return ret;
+}
+
+int SrsFlvDecoder::read_tag_header(char* ptype, int32_t* pdata_size, u_int32_t* ptime)
+{
+    int ret = ERROR_SUCCESS;
+
+    char th[11]; // tag header
+    
+    // read tag header
+    if ((ret = _fs->read(th, 11, NULL)) != ERROR_SUCCESS) {
+        if (ret != ERROR_SYSTEM_FILE_EOF) {
+            srs_error("read flv tag header failed. ret=%d", ret);
+        }
+        return ret;
+    }
+    
+    // Reserved UB [2]
+    // Filter UB [1]
+    // TagType UB [5]
+    *ptype = (int)(th[0] & 0x1F);
+    
+    // DataSize UI24
+    char* pp = (char*)pdata_size;
+    pp[2] = th[1];
+    pp[1] = th[2];
+    pp[0] = th[3];
+    
+    // Timestamp UI24
+    pp = (char*)ptime;
+    pp[2] = th[4];
+    pp[1] = th[5];
+    pp[0] = th[6];
+    
+    // TimestampExtended UI8
+    pp[3] = th[7];
+
+    return ret;
+}
+
+int SrsFlvDecoder::read_tag_data(char* data, int32_t size)
+{
+    int ret = ERROR_SUCCESS;
+    
+    if ((ret = _fs->read(data, size, NULL)) != ERROR_SUCCESS) {
+        if (ret != ERROR_SYSTEM_FILE_EOF) {
+            srs_error("read flv tag header failed. ret=%d", ret);
+        }
+        return ret;
+    }
+    
+    return ret;
+
+}
+
+int SrsFlvDecoder::read_previous_tag_size(char ts[4])
+{
+    int ret = ERROR_SUCCESS;
+    
+    // ignore 4bytes tag size.
+    if ((ret = _fs->read(ts, 4, NULL)) != ERROR_SUCCESS) {
+        if (ret != ERROR_SYSTEM_FILE_EOF) {
+            srs_error("read flv previous tag size failed. ret=%d", ret);
+        }
+        return ret;
+    }
+    
+    return ret;
+}
+

trunk/src/kernel/srs_kernel_flv.hpp

@@ -0,0 +1,170 @@
+/*
+The MIT License (MIT)
+
+Copyright (c) 2013-2014 winlin
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+#ifndef SRS_APP_FLV_HPP
+#define SRS_APP_FLV_HPP
+
+/*
+#include <srs_kernel_flv.hpp>
+*/
+#include <srs_core.hpp>
+
+class SrsStream;
+
+/**
+* file stream to read/write file.
+*/
+class SrsFileStream
+{
+private:
+    std::string _file;
+    int fd;
+public:
+    SrsFileStream();
+    virtual ~SrsFileStream();
+public:
+    virtual int open_write(std::string file);
+    virtual int open_read(std::string file);
+    virtual void close();
+    virtual bool is_open();
+public:
+    /**
+    * @param pnread, return the read size. NULL to ignore.
+    */
+    virtual int read(void* buf, size_t count, ssize_t* pnread);
+    /**
+    * @param pnwrite, return the write size. NULL to ignore.
+    */
+    virtual int write(void* buf, size_t count, ssize_t* pnwrite);
+    /**
+    * tell current offset of stream.
+    */
+    virtual int64_t tellg();
+    virtual int64_t lseek(int64_t offset);
+    virtual int64_t filesize();
+    virtual void skip(int64_t size);
+};
+
+/**
+* encode data to flv file.
+*/
+class SrsFlvEncoder
+{
+private:
+    SrsFileStream* _fs;
+private:
+    SrsStream* tag_stream;
+public:
+    SrsFlvEncoder();
+    virtual ~SrsFlvEncoder();
+public:
+    /**
+    * initialize the underlayer file stream,
+    * user can initialize multiple times to encode multiple flv files.
+    */
+    virtual int initialize(SrsFileStream* fs);
+public:
+    /**
+    * write flv header.
+    * write following:
+    *   1. E.2 The FLV header
+    *   2. PreviousTagSize0 UI32 Always 0
+    * that is, 9+4=13bytes.
+    */
+    virtual int write_header();
+    /**
+    * write flv metadata. 
+    * serialize from:
+    *   AMF0 string: onMetaData,
+    *   AMF0 object: the metadata object.
+    */
+    virtual int write_metadata(char* data, int size);
+    /**
+    * write audio/video packet.
+    */
+    virtual int write_audio(int64_t timestamp, char* data, int size);
+    virtual int write_video(int64_t timestamp, char* data, int size);
+private:
+    virtual int write_tag(char* header, int header_size, char* tag, int tag_size);
+};
+
+/**
+* decode flv fast by only decoding the header and tag.
+*/
+class SrsFlvFastDecoder
+{
+private:
+    SrsFileStream* _fs;
+private:
+    SrsStream* tag_stream;
+public:
+    SrsFlvFastDecoder();
+    virtual ~SrsFlvFastDecoder();
+public:
+    /**
+    * initialize the underlayer file stream,
+    * user can initialize multiple times to encode multiple flv files.
+    */
+    virtual int initialize(SrsFileStream* fs);
+public:
+    /**
+    * read the flv header and size.
+    */
+    virtual int read_header(char** pdata, int* psize);
+    /**
+    * read the sequence header and size.
+    */
+    virtual int read_sequence_header(int64_t* pstart, int* psize);
+public:
+    /**
+    * for start offset, seed to this position and response flv stream.
+    */
+    virtual int lseek(int64_t offset);
+};
+
+/**
+* decode flv file.
+*/
+class SrsFlvDecoder
+{
+private:
+    SrsFileStream* _fs;
+private:
+    SrsStream* tag_stream;
+public:
+    SrsFlvDecoder();
+    virtual ~SrsFlvDecoder();
+public:
+    /**
+    * initialize the underlayer file stream,
+    * user can initialize multiple times to decode multiple flv files.
+    */
+    virtual int initialize(SrsFileStream* fs);
+public:
+    virtual int read_header(char header[9]);
+    virtual int read_tag_header(char* ptype, int32_t* pdata_size, u_int32_t* ptime);
+    virtual int read_tag_data(char* data, int32_t size);
+    virtual int read_previous_tag_size(char ts[4]);
+};
+
+#endif