注:写了一系列的有关ffdshow对解码器的封装的代码,列表如下:
ffdshow 源代码分析 6: 对解码器的dll的封装(libavcodec)
ffdshow 源代码分析 7: libavcodec视频解码器类(TvideoCodecLibavcodec)
ffdshow 源代码分析 8: 视频解码器类(TvideoCodecDec)
ffdshow 源代码分析 9: 编解码器有关类的总结
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前面两篇文章介绍了ffdshow中libavcodec的封装类Tlibavcodec,以及libavcodec的解码器类TvideoCodecLibavcodec:
ffdshow 源代码分析 6: 对解码器的dll的封装(libavcodec)
ffdshow 源代码分析 7: 解码器类(TvideoCodecLibavcodec)
其中libavcodec的解码器类TvideoCodecLibavcodec通过调用Tlibavcodec中的方法实现了libavcodec的dll中方法的调用;而它继承了TvideoCodecDec,本文正是要分析它继承的这个类。
TvideoCodecDec是所有视频解码器共有的父类。可以看一下它的继承关系:
可见,除了TvideoCodecLibavcodec继承了TvideoCodecDec之外,还有好几个类继承了TvideoCodecDec,比如说:TvideoCodecLibmpeg2,TvideoCodecXviD4等等…。突然来了兴趣,我们可以看一下其他的解码器类的定义是什么样的。
TvideoCodecLibmpeg2定义如下:
/* *雷霄骅 *[email protected] *中国传媒大学/数字电视技术 */ #ifndef _TVIDEOCODECLIBMPEG2_H_ #define _TVIDEOCODECLIBMPEG2_H_ #include "TvideoCodec.h" #include "libmpeg2/include/mpeg2.h" class Tdll; struct Textradata; class TccDecoder; //libmpeg2解码器 class TvideoCodecLibmpeg2 : public TvideoCodecDec { private: Tdll *dll; uint32_t (*mpeg2_set_accel)(uint32_t accel); mpeg2dec_t* (*mpeg2_init)(void); const mpeg2_info_t* (*mpeg2_info)(mpeg2dec_t *mpeg2dec); mpeg2_state_t (*mpeg2_parse)(mpeg2dec_t *mpeg2dec); void (*mpeg2_buffer)(mpeg2dec_t *mpeg2dec, const uint8_t *start, const uint8_t *end); void (*mpeg2_close)(mpeg2dec_t *mpeg2dec); void (*mpeg2_reset)(mpeg2dec_t *mpeg2dec, int full_reset); void (*mpeg2_set_rtStart)(mpeg2dec_t *mpeg2dec, int64_t rtStart); int (*mpeg2_guess_aspect)(const mpeg2_sequence_t * sequence, unsigned int * pixel_width, unsigned int * pixel_height); mpeg2dec_t *mpeg2dec; const mpeg2_info_t *info; bool wait4Iframe; int sequenceFlag; REFERENCE_TIME avgTimePerFrame; TffPict oldpict; Textradata *extradata; TccDecoder *ccDecoder; Tbuffer *buffer; uint32_t oldflags; bool m_fFilm; int SetDeinterlaceMethod(void); void init(void); HRESULT decompressI(const unsigned char *src, size_t srcLen, IMediaSample *pIn); protected: virtual bool beginDecompress(TffPictBase &pict, FOURCC infcc, const CMediaType &mt, int sourceFlags); public: TvideoCodecLibmpeg2(IffdshowBase *Ideci, IdecVideoSink *Isink); virtual ~TvideoCodecLibmpeg2(); static const char_t *dllname; virtual int getType(void) const { return IDFF_MOVIE_LIBMPEG2; } virtual int caps(void) const { return CAPS::VIS_QUANTS; } virtual void end(void); virtual HRESULT decompress(const unsigned char *src, size_t srcLen, IMediaSample *pIn); virtual bool onSeek(REFERENCE_TIME segmentStart); virtual HRESULT BeginFlush(); }; #endif
TvideoCodecXviD4定义如下:
/* *雷霄骅 *[email protected] *中国传媒大学/数字电视技术 */ #ifndef _TVIDEOCODECXVID4_H_ #define _TVIDEOCODECXVID4_H_ #include "TvideoCodec.h" class Tdll; struct Textradata; //xvid解码器 class TvideoCodecXviD4 : public TvideoCodecDec { private: void create(void); Tdll *dll; public: TvideoCodecXviD4(IffdshowBase *Ideci, IdecVideoSink *IsinkD); virtual ~TvideoCodecXviD4(); int (*xvid_global)(void *handle, int opt, void *param1, void *param2); int (*xvid_decore)(void *handle, int opt, void *param1, void *param2); int (*xvid_plugin_single)(void *handle, int opt, void *param1, void *param2); int (*xvid_plugin_lumimasking)(void *handle, int opt, void *param1, void *param2); static const char_t *dllname; private: void *enchandle, *dechandle; int psnr; TffPict pict; Tbuffer pictbuf; static int me_hq(int rd3), me_(int me3); Textradata *extradata; REFERENCE_TIME rtStart, rtStop; protected: virtual bool beginDecompress(TffPictBase &pict, FOURCC infcc, const CMediaType &mt, int sourceFlags); virtual HRESULT flushDec(void); public: virtual int getType(void) const { return IDFF_MOVIE_XVID4; } virtual int caps(void) const { return CAPS::VIS_QUANTS; } virtual HRESULT decompress(const unsigned char *src, size_t srcLen, IMediaSample *pIn); }; #endif
从以上这2种解码器类的定义,我们可以看出一些规律,比如说:
1. 都有Tdll *dll这个变量,用于加载视频解码器的dll
好了,闲话不说,回归正题,来看一下这些解码器共有的父类:TvideoCodecDec
//具体 视频 解码器的父类,存一些公共信息 class TvideoCodecDec : virtual public TvideoCodec, virtual public TcodecDec { protected: bool isdvdproc; comptrQ<IffdshowDecVideo> deciV; IdecVideoSink *sinkD; TvideoCodecDec(IffdshowBase *Ideci, IdecVideoSink *Isink); Rational guessMPEG2sar(const Trect &r, const Rational &sar2, const Rational &containerSar); class TtelecineManager { private: TvideoCodecDec* parent; int segment_count; int pos_in_group; struct { int fieldtype; int repeat_pict; REFERENCE_TIME rtStart; } group[2]; // store information about 2 recent frames. REFERENCE_TIME group_rtStart; bool film; int cfg_softTelecine; public: TtelecineManager(TvideoCodecDec* Iparent); void get_timestamps(TffPict &pict); void get_fieldtype(TffPict &pict); void new_frame(int top_field_first, int repeat_pict, const REFERENCE_TIME &rtStart, const REFERENCE_TIME &rtStop); void onSeek(void); } telecineManager; public: static TvideoCodecDec* initDec(IffdshowBase *deci, IdecVideoSink *Isink, AVCodecID codecId, FOURCC fcc, const CMediaType &mt); virtual ~TvideoCodecDec(); virtual int caps(void) const { return CAPS::NONE; } virtual bool testMediaType(FOURCC fcc, const CMediaType &mt) { return true; } virtual void forceOutputColorspace(const BITMAPINFOHEADER *hdr, int *ilace, TcspInfos &forcedCsps) { *ilace = 0; //cspInfos of forced output colorspace, empty when entering function } enum {SOURCE_REORDER = 1}; virtual bool beginDecompress(TffPictBase &pict, FOURCC infcc, const CMediaType &mt, int sourceFlags) = 0; virtual HRESULT decompress(const unsigned char *src, size_t srcLen, IMediaSample *pIn) = 0; virtual bool onDiscontinuity(void) { return false; } virtual HRESULT onEndOfStream(void) { return S_OK; } unsigned int quantsDx, quantsStride, quantsDy, quantBytes, quantType; //QP表 void *quants; uint16_t *intra_matrix, *inter_matrix; //计算平均QP float calcMeanQuant(void); //画运动矢量 virtual bool drawMV(unsigned char *dst, unsigned int dx, stride_t stride, unsigned int dy) const { return false; } virtual const char* get_current_idct(void) { return NULL; } virtual int useDXVA(void) { return 0; }; virtual void setOutputPin(IPin * /*pPin*/) {} };
TvideoCodecDec这个类中,还定义了一个类TtelecineManager。这种在类里面再定义一个类的方式还是不太多见的。TtelecineManager这个类的作用还没有研究,先不管它。
可以看出,TvideoCodecDec类的定义并不复杂,最主要的变量有如下几个,这几个变量都是子类中会用到的:
comptrQ<IffdshowDecVideo>deciV:重要性不言而喻,回头介绍
IdecVideoSink *sinkD:重要性不言而喻,回头介绍
void *quants:QP表(为什么要存在这里还没搞清)
TvideoCodecDec类定义了几个函数:
TvideoCodecDec类还定义了一些纯虚函数,作为接口,这些函数的实现都在TvideoCodecDec的子类中完成【这几个函数是最重要的】:
beginDecompress();TvideoCodecDec类中最重要的函数只有一个,就是initDec(),作用主要是初始化解码器。其他的很多函数大多只是定义了一个名称,并没有实现,因为都是打算在具体各种解码器类中再进行实现的。
看一下initDec()的代码:
TvideoCodecDec* TvideoCodecDec::initDec(IffdshowBase *deci, IdecVideoSink *sink, AVCodecID codecId, FOURCC fcc, const CMediaType &mt) { // DXVA mode is a preset setting switch (codecId) { case AV_CODEC_ID_H264: if (deci->getParam2(IDFF_filterMode) & IDFF_FILTERMODE_VIDEODXVA) { if (deci->getParam2(IDFF_dec_DXVA_H264)) { codecId = CODEC_ID_H264_DXVA; } else { return NULL; } } break; case AV_CODEC_ID_VC1: case CODEC_ID_WMV9_LIB: if (deci->getParam2(IDFF_filterMode) & IDFF_FILTERMODE_VIDEODXVA) { if (deci->getParam2(IDFF_dec_DXVA_VC1)) { codecId = CODEC_ID_VC1_DXVA; } else { return NULL; } } break; default: break; } TvideoCodecDec *movie = NULL; if (is_quicksync_codec(codecId)) { movie = new TvideoCodecQuickSync(deci, sink, codecId); } else if (lavc_codec(codecId)) { movie = new TvideoCodecLibavcodec(deci, sink); } else if (raw_codec(codecId)) { movie = new TvideoCodecUncompressed(deci, sink); } else if (wmv9_codec(codecId)) { movie = new TvideoCodecWmv9(deci, sink); } else if (codecId == CODEC_ID_XVID4) { movie = new TvideoCodecXviD4(deci, sink); } else if (codecId == CODEC_ID_LIBMPEG2) { movie = new TvideoCodecLibmpeg2(deci, sink); } else if (codecId == CODEC_ID_AVISYNTH) { movie = new TvideoCodecAvisynth(deci, sink); } else if (codecId == CODEC_ID_H264_DXVA || codecId == CODEC_ID_VC1_DXVA) { movie = new TvideoCodecLibavcodecDxva(deci, sink, codecId); } else { return NULL; } if (!movie) { return NULL; } if (movie->ok && movie->testMediaType(fcc, mt)) { movie->codecId = codecId; return movie; } else if (is_quicksync_codec(codecId)) { // QuickSync decoder init failed, revert to internal decoder. switch (codecId) { case CODEC_ID_H264_QUICK_SYNC: codecId = AV_CODEC_ID_H264; break; case CODEC_ID_MPEG2_QUICK_SYNC: codecId = CODEC_ID_LIBMPEG2; break; case CODEC_ID_VC1_QUICK_SYNC: codecId = CODEC_ID_WMV9_LIB; break; default: ASSERT(FALSE); // this shouldn't happen! } delete movie; // Call this function again with the new codecId. return initDec(deci, sink, codecId, fcc, mt); } else { delete movie; return NULL; } }
这个函数的功能还是比较好理解的,根据CodecID的不同,创建不同的解码器(从TvideoCodecLibavcodec,TvideoCodecXviD4,TvideoCodecLibmpeg2这些里面选择)。
虽然不知道用途是什么,但是我们可以顺便看一下计算平均QP的函数,就是把quants1指向的QP表里面的数据求了一个平均值:
//计算平均QP float TvideoCodecDec::calcMeanQuant(void) { if (!quants || !quantsDx || !quantsDy) { return 0; } unsigned int sum = 0, num = quantsDx * quantsDy; unsigned char *quants1 = (unsigned char*)quants; for (unsigned int y = 0; y < quantsDy; y++) for (unsigned int x = 0; x < quantsDx; x++) { sum += quants1[(y * quantsStride + x) * quantBytes]; } return float(sum) / num; }