XBMC源代码分析 7：视频播放器（dvdplayer）-输入流（以libRTMP为例）
前文分析了XBMC的基本结构：
XBMC源代码分析 1：整体结构以及编译方法
XBMC源代码分析 2：Addons（皮肤Skin）
XBMC源代码分析 3：核心部分（core）-综述
XBMC源代码分析 4：视频播放器（dvdplayer）-解码器（以ffmpeg为例）
XBMC源代码简析 5：视频播放器（dvdplayer）-解复用器（以ffmpeg为例）
XBMC源代码分析 6：视频播放器（dvdplayer）-文件头（以ffmpeg为例）
本文我们分析XBMC中视频播放器（dvdplayer）中的输入流部分。由于输入流种类很多，因此以RTMP输入流为例进行分析。
XBMC中输入流部分文件目录结构如下图所示。
从目录中文件的名称我们可以看出，XBMC支持多种输入方式：File，HTSP，HTTP，RTMP等等。在这里我们看看RTMP部分的源代码。对应DVDInputStreamRTMP.h和DVDInputStreamRTMP.cpp
先来看看DVDInputStreamRTMP.h
/* * 雷霄骅 * [email protected] * 中国传媒大学/数字电视技术 * */ //如果有libRTMP #ifdef HAS_LIBRTMP #include "DVDInputStream.h" #include "DllLibRTMP.h" //支持RTMP输入流的类，继承CDVDInputStream class CDVDInputStreamRTMP : public CDVDInputStream , public CDVDInputStream::ISeekTime { public: CDVDInputStreamRTMP(); virtual ~CDVDInputStreamRTMP(); virtual bool Open(const char* strFile, const std::string &content);//打开 virtual void Close();//关闭 virtual int Read(uint8_t* buf, int buf_size);//读取 virtual int64_t Seek(int64_t offset, int whence);//跳转到 bool SeekTime(int iTimeInMsec); virtual bool Pause(double dTime);//暂停 virtual bool IsEOF(); virtual int64_t GetLength(); CCriticalSection m_RTMPSection; protected: bool m_eof; bool m_bPaused; char* m_sStreamPlaying; std::vector<CStdString> m_optionvalues; RTMP *m_rtmp; DllLibRTMP m_libRTMP; }; #endif
该类中包含了Open()，Close()，Read()，Seek()，Pause() 这类的方法。实现了对RTMP协议的各种操作。这些方法都是CDVDInputStreamRTMP父类CDVDInputStream中的方法。可以看一下CDVDInputStream的定义，就知道了。
//输入流类
class CDVDInputStream
{
public:
class IChannel
{
public:
virtual ~IChannel() {};
virtual bool NextChannel(bool preview = false) = 0;
virtual bool PrevChannel(bool preview = false) = 0;
virtual bool SelectChannelByNumber(unsigned int channel) = 0;
virtual bool SelectChannel(const PVR::CPVRChannel &channel) { return false; };
virtual bool GetSelectedChannel(PVR::CPVRChannelPtr&) { return false; };
virtual bool UpdateItem(CFileItem& item) = 0;
virtual bool CanRecord() = 0;
virtual bool IsRecording() = 0;
virtual bool Record(bool bOnOff) = 0;
virtual bool CanPause() = 0;
virtual bool CanSeek() = 0;
};
class IDisplayTime
{
public:
virtual ~IDisplayTime() {};
virtual int GetTotalTime() = 0;
virtual int GetTime() = 0;
};
class ISeekTime
{
public:
virtual ~ISeekTime() {};
virtual bool SeekTime(int ms) = 0;
};
class IChapter
{
public:
virtual ~IChapter() {};
virtual int GetChapter() = 0;
virtual int GetChapterCount() = 0;
virtual void GetChapterName(std::string& name) = 0;
virtual bool SeekChapter(int ch) = 0;
};
class IMenus
{
public:
virtual ~IMenus() {};
virtual void ActivateButton() = 0;
virtual void SelectButton(int iButton) = 0;
virtual int GetCurrentButton() = 0;
virtual int GetTotalButtons() = 0;
virtual void OnUp() = 0;
virtual void OnDown() = 0;
virtual void OnLeft() = 0;
virtual void OnRight() = 0;
virtual void OnMenu() = 0;
virtual void OnBack() = 0;
virtual void OnNext() = 0;
virtual void OnPrevious() = 0;
virtual bool OnMouseMove(const CPoint &point) = 0;
virtual bool OnMouseClick(const CPoint &point) = 0;
virtual bool IsInMenu() = 0;
virtual void SkipStill() = 0;
virtual double GetTimeStampCorrection() = 0;
virtual bool GetState(std::string &xmlstate) = 0;
virtual bool SetState(const std::string &xmlstate) = 0;
};
class ISeekable
{
public:
virtual ~ISeekable() {};
virtual bool CanSeek() = 0;
virtual bool CanPause() = 0;
};
enum ENextStream
{
NEXTSTREAM_NONE,
NEXTSTREAM_OPEN,
NEXTSTREAM_RETRY,
};
CDVDInputStream(DVDStreamType m_streamType);
virtual ~CDVDInputStream();
virtual bool Open(const char* strFileName, const std::string& content);//打开
virtual void Close() = 0;//关闭
virtual int Read(uint8_t* buf, int buf_size) = 0;//读取
virtual int64_t Seek(int64_t offset, int whence) = 0;//跳转
virtual bool Pause(double dTime) = 0;//暂停
virtual int64_t GetLength() = 0;
virtual std::string& GetContent() { return m_content; };
virtual std::string& GetFileName() { return m_strFileName; }
virtual CURL &GetURL() { return m_url; }
virtual ENextStream NextStream() { return NEXTSTREAM_NONE; }
virtual void Abort() {}
virtual int GetBlockSize() { return 0; }
virtual void ResetScanTimeout(unsigned int iTimeoutMs) { }
/*! \brief Indicate expected read rate in bytes per second.
* This could be used to throttle caching rate. Should
* be seen as only a hint
*/
virtual void SetReadRate(unsigned rate) {}
/*! \brief Get the cache status
\return true when cache status was succesfully obtained
*/
virtual bool GetCacheStatus(XFILE::SCacheStatus *status) { return false; }
bool IsStreamType(DVDStreamType type) const { return m_streamType == type; }
virtual bool IsEOF() = 0;
virtual BitstreamStats GetBitstreamStats() const { return m_stats; }
void SetFileItem(const CFileItem& item);
protected:
DVDStreamType m_streamType;
std::string m_strFileName;
CURL m_url;
BitstreamStats m_stats;
std::string m_content;
CFileItem m_item;
};
回到CDVDInputStreamRTMP类本身。可以看一下Open()，Close()，Read()，Seek()，Pause()这些方法的函数体。这些方方通过调用libRTMP中相应的方法，完成了对RTMP流媒体的各种操作。
/* * 雷霄骅 * [email protected] * 中国传媒大学/数字电视技术 * */ //打开 bool CDVDInputStreamRTMP::Open(const char* strFile, const std::string& content) { if (m_sStreamPlaying) { free(m_sStreamPlaying); m_sStreamPlaying = NULL; } if (!CDVDInputStream::Open(strFile, "video/x-flv")) return false; CSingleLock lock(m_RTMPSection); // libRTMP can and will alter strFile, so take a copy of it m_sStreamPlaying = (char*)calloc(strlen(strFile)+1,sizeof(char)); strcpy(m_sStreamPlaying,strFile); //libRTMP中的设置URL if (!m_libRTMP.SetupURL(m_rtmp, m_sStreamPlaying)) return false; // SetOpt and SetAVal copy pointers to the value. librtmp doesn't use the values until the Connect() call, // so value objects must stay allocated until then. To be extra safe, keep the values around until Close(), // in case librtmp needs them again. m_optionvalues.clear(); for (int i=0; options[i].name; i++) { CStdString tmp = m_item.GetProperty(options[i].name).asString(); if (!tmp.empty()) { m_optionvalues.push_back(tmp); AVal av_tmp; SetAVal(av_tmp, m_optionvalues.back()); m_libRTMP.SetOpt(m_rtmp, &options[i].key, &av_tmp); } } //建立RTMP链接中的NetConnection和NetStream if (!m_libRTMP.Connect(m_rtmp, NULL) || !m_libRTMP.ConnectStream(m_rtmp, 0)) return false; m_eof = false; return true; } //关闭 // close file and reset everything void CDVDInputStreamRTMP::Close() { CSingleLock lock(m_RTMPSection); CDVDInputStream::Close(); //关闭连接 m_libRTMP.Close(m_rtmp); m_optionvalues.clear(); m_eof = true; m_bPaused = false; } //读取 int CDVDInputStreamRTMP::Read(uint8_t* buf, int buf_size) {//读取 int i = m_libRTMP.Read(m_rtmp, (char *)buf, buf_size); if (i < 0) m_eof = true; return i; } //跳转到 int64_t CDVDInputStreamRTMP::Seek(int64_t offset, int whence) { if (whence == SEEK_POSSIBLE) return 0; else return -1; } //暂停 bool CDVDInputStreamRTMP::Pause(double dTime) { CSingleLock lock(m_RTMPSection); m_bPaused = !m_bPaused; CLog::Log(LOGNOTICE, "RTMP Pause %s requested", m_bPaused ? "TRUE" : "FALSE"); m_libRTMP.Pause(m_rtmp, m_bPaused); return true; }