C++ BS_Begin函数代码示例

//---------------------------------------------------------------------------
// Packet "B0"
void File_AvsV::video_sequence_start()
{
    Element_Name("video_sequence_start");

    //Parsing
    int32u bit_rate_upper, bit_rate_lower;
    Get_B1 (    profile_id,                                     "profile_id");
    Get_B1 (    level_id,                                       "level_id");
    BS_Begin();
    Get_SB (    progressive_sequence,                           "progressive_sequence");
    Get_S2 (14, horizontal_size,                                "horizontal_size");
    Get_S2 (14, vertical_size,                                  "vertical_size");
    Get_S1 ( 2, chroma_format,                                  "chroma_format");
    Skip_S1( 3,                                                 "sample_precision");
    Get_S1 ( 4, aspect_ratio,                                   "aspect_ratio"); Param_Info(AvsV_aspect_ratio[aspect_ratio]);
    Get_S1 ( 4, frame_rate_code,                                "frame_rate_code"); Param_Info(AvsV_frame_rate[frame_rate_code]);
    Get_S3 (18, bit_rate_lower,                                 "bit_rate_lower");
    Mark_1 ();
    Get_S3 (12, bit_rate_upper,                                 "bit_rate_upper");
    bit_rate=(bit_rate_upper<<18)+bit_rate_lower; Param_Info(bit_rate*8, " bps");
    Get_SB (    low_delay,                                      "low_delay");
    Mark_1 ();
    Skip_S3(18,                                                 "bbv_buffer_size");
    Skip_SB(                                                    "reserved");
    Skip_SB(                                                    "reserved");
    Skip_SB(                                                    "reserved");
    BS_End();

    //Not sure, but the 3 first official files have this
    if (Element_Size-Element_Offset)
    {
        BS_Begin();
        Mark_1();
        BS_End();
    }

    FILLING_BEGIN();
        //NextCode
        NextCode_Clear();
        NextCode_Add(0xB2); //user_data_start
        NextCode_Add(0xB3); //picture_start (I)
        NextCode_Add(0xB5); //extension_start

        //Autorisation of other streams
        Streams[0xB1].Searching_Payload=true, //video_sequence_end
        Streams[0xB2].Searching_Payload=true; //user_data_start
        Streams[0xB3].Searching_Payload=true, //picture_start (I)
        Streams[0xB4].Searching_Payload=true, //reserved
        Streams[0xB5].Searching_Payload=true; //extension_start
        Streams[0xB6].Searching_Payload=true, //picture_start (P or B)
        Streams[0xB7].Searching_Payload=true; //video_edit
        Streams[0xB8].Searching_Payload=true, //reserved

        video_sequence_start_IsParsed=true;
    FILLING_END();
}

//---------------------------------------------------------------------------
void File_Cdp::ccsvcinfo_section()
{
    //Parsing
    int8u svc_count;
    Element_Begin1("ccsvcinfo_section");
    Skip_B1(                                                    "ccsvcinfo_id");
    BS_Begin();
    Skip_SB(                                                    "reserved");
    Skip_SB(                                                    "svc_info_start");
    Skip_SB(                                                    "svc_info_change");
    Skip_SB(                                                    "svc_info_complete");
    Get_S1 (4, svc_count,                                       "svc_count");
    BS_End();
    for (int8u Pos=0; Pos<svc_count; Pos++)
    {
        Element_Begin1("svc");
        bool  csn_size;
        BS_Begin();
        Skip_SB(                                                "reserved");
        Get_SB (   csn_size,                                    "csn_size");
        if (csn_size)
        {
            Skip_SB(                                            "reserved");
            Skip_S1(5,                                          "caption_service_number");
        }
        else
            Skip_S1(6,                                          "caption_service_number");
        BS_End();

        //svc_data_byte - caption_service_descriptor
        Element_Begin1("service");
        Ztring language;
        bool digital_cc;
        Get_Local(3, language,                                  "language");
        BS_Begin();
        Get_SB (digital_cc,                                     "digital_cc");
        Skip_SB(                                                "reserved");
        if (digital_cc) //line21
        {
            Skip_S1(5,                                          "reserved");
            Skip_SB(                                            "line21_field");
        }
        else
            Skip_S1(6,                                          "caption_service_number");
        Skip_SB(                                                "easy_reader");
        Skip_SB(                                                "wide_aspect_ratio");
        Skip_S2(14,                                             "reserved");
        BS_End();
        Element_End0();
        Element_End0();
    }
    Element_End0();
}

//---------------------------------------------------------------------------
void File_Jpeg::COD()
{
    //Parsing
    int16u Levels;
    int8u Style, Style2, MultipleComponentTransform;
    bool PrecinctUsed;
    Get_B1 (Style,                                              "Scod - Style");
        Get_Flags (Style, 0, PrecinctUsed,                      "Precinct used");
        Skip_Flags(Style, 1,                                    "Use SOP (start of packet)");
        Skip_Flags(Style, 2,                                    "Use EPH (end of packet header)");
    Skip_B1(                                                    "Number of decomposition levels");
    Skip_B1(                                                    "Progression order");
    Get_B2 (Levels,                                             "Number of layers");
    Info_B1(DimX,                                               "Code-blocks dimensions X (2^(n+2))"); Param_Info2(1<<(DimX+2), " pixels");
    Info_B1(DimY,                                               "Code-blocks dimensions Y (2^(n+2))"); Param_Info2(1<<(DimY+2), " pixels");
    Get_B1 (Style2,                                             "Style of the code-block coding passes");
        Skip_Flags(Style, 0,                                    "Selective arithmetic coding bypass");
        Skip_Flags(Style, 1,                                    "MQ states for all contexts");
        Skip_Flags(Style, 2,                                    "Regular termination");
        Skip_Flags(Style, 3,                                    "Vertically stripe-causal context formation");
        Skip_Flags(Style, 4,                                    "Error resilience info is embedded on MQ termination");
        Skip_Flags(Style, 5,                                    "Segmentation marker is to be inserted at the end of each normalization coding pass");
    Skip_B1(                                                    "Transform");
    Get_B1(MultipleComponentTransform,                          "Multiple component transform");
    if (PrecinctUsed)
    {
        BS_Begin();
        Skip_S1(4,                                              "LL sub-band width");
        Skip_S1(4,                                              "LL sub-band height");
        BS_End();
        for (int16u Pos=0; Pos<Levels; Pos++)
        {
            Element_Begin1("Decomposition level");
            BS_Begin();
            Skip_S1(4,                                          "decomposition level width");
            Skip_S1(4,                                          "decomposition level height");
            BS_End();
            Element_End0();
        }
    }

    FILLING_BEGIN();
        if (Frame_Count==0 && Field_Count==0)
        {
            switch (MultipleComponentTransform)
            {
                case 0x01 : Fill(StreamKind_Last, 0, "Compression_Mode", "Lossless"); break;
                case 0x02 : Fill(StreamKind_Last, 0, "Compression_Mode", "Lossy"); break;
                default   : ;
            }
        }
    FILLING_END();
}

//---------------------------------------------------------------------------
void File_Sdp::Header_Parse()
{
    //Parsing
    int8u Length, FormatCode;
    Skip_B2(                                                    "Identifier");
    Get_B1 (Length,                                             "Length");
    Get_B1 (FormatCode,                                         "Format Code");
    for (int8u Pos=0; Pos<5; Pos++)
    {
        FieldLines[Pos]=0;
        #if MEDIAINFO_TRACE
            Element_Begin1("Field/Line");
            BS_Begin();
            Info_SB(   Field,                                   "Field Number");
            Info_S1(2, Reserved,                                "Reserved");
            Info_S1(5, Line,                                    "Line Number");
            BS_End();
            FieldLines[Pos]=((Field?1:0)<<7) |(Reserved<<5) | Line; //Removing field information ((Field?1:0)<<7) |
            if (FieldLines[Pos])
            {
                Element_Info1(Field?2:1);
                Element_Info1(Line);
            }
            else
                Element_Info1("None");
            Element_End0();
        #else //MEDIAINFO_TRACE
            Get_B1(FieldLines[Pos],                             "Field/Line");
            FieldLines[Pos]&=0x7F; //Removing field information
        #endif //MEDIAINFO_TRACE
    }

    Header_Fill_Size(3+Length);
}

//---------------------------------------------------------------------------
void File_Flac::STREAMINFO()
{
    Element_Info("STREAMINFO");

    //Parsing
    int64u Samples;
    int32u FrameSize_Min, FrameSize_Max, SampleRate;
    int8u  Channels, BitPerSample;
    Skip_B2(                                                    "BlockSize_Min"); //The minimum block size (in samples) used in the stream.
    Skip_B2(                                                    "BlockSize_Max"); //The maximum block size (in samples) used in the stream. (Minimum blocksize == maximum blocksize) implies a fixed-blocksize stream.
    Get_B3 (    FrameSize_Min,                                  "FrameSize_Min"); //The minimum frame size (in bytes) used in the stream. May be 0 to imply the value is not known.
    Get_B3 (    FrameSize_Max,                                  "FrameSize_Max"); //The maximum frame size (in bytes) used in the stream. May be 0 to imply the value is not known.
    BS_Begin();
    Get_S3 (20, SampleRate,                                     "SampleRate"); //Sample rate in Hz. Though 20 bits are available, the maximum sample rate is limited by the structure of frame headers to 1048570Hz. Also, a value of 0 is invalid.
    Get_S1 ( 3, Channels,                                       "Channels"); Param_Info(Channels+1, " channels"); //(number of channels)-1. FLAC supports from 1 to 8 channels
    Get_S1 ( 5, BitPerSample,                                   "BitPerSample"); Param_Info(BitPerSample+1, " bits"); //(bits per sample)-1. FLAC supports from 4 to 32 bits per sample. Currently the reference encoder and decoders only support up to 24 bits per sample.
    Get_S5 (36, Samples,                                        "Samples");
    BS_End();
    Skip_B16(                                                   "MD5 signature of the unencoded audio data");

    //Filling
    if (SampleRate==0)
        return;
    Stream_Prepare(Stream_Audio);
    Fill(Stream_Audio, 0, Audio_Format, "FLAC");
    Fill(Stream_Audio, 0, Audio_Codec, "FLAC");
    if (FrameSize_Min==FrameSize_Max && FrameSize_Min!=0 ) // 0 means it is unknown
        Fill(Stream_Audio, 0, Audio_BitRate_Mode, "CBR");
     else
        Fill(Stream_Audio, 0, Audio_BitRate_Mode, "VBR");
    Fill(Stream_Audio, 0, Audio_SamplingRate, SampleRate);
    Fill(Stream_Audio, 0, Audio_Channel_s_, Channels+1);
    Fill(Stream_Audio, 0, Audio_Resolution, BitPerSample+1);
    Fill(Stream_Audio, 0, Audio_Duration, Samples*1000/SampleRate);
}

//---------------------------------------------------------------------------
void File_Mpeg4_Descriptors::Descriptor_03()
{
    //Parsing
    bool streamDependenceFlag, URL_Flag, OCRstreamFlag;
    Get_B2 (ES_ID,                                              "ES_ID");
    BS_Begin();
    Get_SB (   streamDependenceFlag,                            "streamDependenceFlag");
    Get_SB (   URL_Flag,                                        "URL_Flag");
    Get_SB (   OCRstreamFlag,                                   "OCRstreamFlag");
    Skip_S1(5,                                                  "streamPriority");
    BS_End();
    if (streamDependenceFlag)
        Skip_B2(                                                "dependsOn_ES_ID");
    if (URL_Flag)
    {
        int8u URLlength;
        Get_B1 (URLlength,                                      "URLlength");
        Skip_UTF8(URLlength,                                    "URLstring");
    }
    if (OCRstreamFlag)
        Skip_B2(                                                "OCR_ES_Id");

    FILLING_BEGIN();
        Element_ThisIsAList();
    FILLING_END();
}

//---------------------------------------------------------------------------
void File_Vc3::CodingControlA()
{
    //Parsing
    Element_Begin("Coding Control A", 3);
    BS_Begin();

    Mark_0();
    Mark_0();
    Mark_0();
    Mark_0();
    Mark_0();
    Mark_0();
    Info_S1(2, FFC,                                             "Field/Frame Count"); Param_Info(Vc3_FFC[FFC]);

    Mark_1();
    Mark_0();
    Mark_0();
    Get_SB (   CRCF,                                             "CRC flag");
    Mark_0();
    Mark_0();
    Mark_0();
    Mark_0();

    Mark_1();
    Mark_0();
    Mark_1();
    Mark_0();
    Mark_0();
    Mark_0();
    Mark_0();
    Mark_0();

    BS_End();
    Element_End();
}

//---------------------------------------------------------------------------
void File_MpcSv8::SH()
{
    //Parsing
    int64u SampleCount;
    int8u  Version, SampleFrequency, ChannelCount;
    bool   MidSideStereo;
    Skip_B4(                                                    "CRC32");
    Get_B1 (Version,                                            "Version");
    Get_VS (SampleCount,                                        "Sample count");
    Skip_VS(                                                    "Beginning silence");
    BS_Begin();
    Get_S1 (3, SampleFrequency,                                 "Sample frequency"); Param_Info(Mpc_SampleFreq[SampleFrequency]);
    Skip_S1(5,                                                  "Max used bands");
    Get_S1 (4, ChannelCount,                                    "Channel count");
    Get_SB (   MidSideStereo,                                   "Mid side stereo used");
    Skip_S1(3,                                                  "Audio block frames");
    BS_End();

    //Filling
    FILLING_BEGIN();
        Fill(Stream_Audio, 0, Audio_SamplingRate, Mpc_SampleFreq[SampleFrequency]);
        if (SampleCount)
        {
            Fill(Stream_Audio, 0, Audio_SamplingCount, SampleCount);
            Fill(Stream_Audio, 0, Audio_Duration, SampleCount*1000/Mpc_SampleFreq[SampleFrequency]);
            Fill(Stream_Audio, 0, Audio_BitRate, File_Size*8*Mpc_SampleFreq[SampleFrequency]/SampleCount); //Should be more precise...
        }
        Fill(Stream_Audio, 0, Audio_Resolution, 16); //MPC support only 16 bits
    FILLING_END();
}

//---------------------------------------------------------------------------
void File_Pcm_M2ts::Read_Buffer_Continue()
{
    if (Buffer_Size==0)
        return;

    //Parsing
    int16u  audio_data_payload_size;
    Get_B2 (   audio_data_payload_size,                         "audio_data_payload_size");
    BS_Begin();
    Get_S1 (4, channel_assignment,                              "channel_assignment"); Param_Info2(Pcm_M2TS_channel_assignment[channel_assignment], " channel(s)");
    Get_S1 (4, sampling_frequency,                              "sampling_frequency"); Param_Info2(Pcm_M2TS_sampling_frequency[sampling_frequency], " Hz");
    Get_S1 (2, bits_per_sample,                                 "bits_per_sample"); Param_Info2(Pcm_M2TS_bits_per_sample[bits_per_sample], " bits");
    Skip_SB(                                                    "start_flag");
    Skip_S1(5,                                                  "reserved");
    BS_End();
    Skip_XX(audio_data_payload_size,                            "audio_data_payload");

    FILLING_BEGIN_PRECISE();
        if (!Status[IsAccepted])
        {
            Accept();
            Finish();
        }
    FILLING_END();
}

//---------------------------------------------------------------------------
void File_Mpeg4_Descriptors::Descriptor_02()
{
    //Parsing
    bool URL_Flag;
    BS_Begin();
    Skip_S2(10,                                                 "ObjectDescriptorID");
    Get_SB (    URL_Flag,                                       "URL_Flag");
    Skip_SB(                                                    "includeInlineProfileLevelFlag");
    Skip_S1( 4,                                                 "reserved");
    BS_End();
    if (URL_Flag)
    {
        int8u URLlength;
        Get_B1 (URLlength,                                      "URLlength");
        Skip_UTF8(URLlength,                                    "URLstring");
    }
    Info_B1(ODProfileLevel,                                     "ODProfileLevelIndication"); Param_Info(Mpeg4_Descriptors_ODProfileLevelIndication(ODProfileLevel));
    Info_B1(SceneProfileLevel,                                  "sceneProfileLevelIndication"); Param_Info(Mpeg4_Descriptors_SceneProfileLevelIndication(SceneProfileLevel));
    Info_B1(AudioProfileLevel,                                  "audioProfileLevelIndication"); Param_Info(Mpeg4_Descriptors_AudioProfileLevelIndication(AudioProfileLevel));
    Info_B1(VisualProfileLevel,                                 "visualProfileLevelIndication"); Param_Info(Mpeg4_Descriptors_VisualProfileLevelIndication(VisualProfileLevel));
    Info_B1(GraphicsProfileLevel,                               "graphicsProfileLevelIndication"); Param_Info(Mpeg4_Descriptors_GraphicsProfileLevelIndication(GraphicsProfileLevel));

    FILLING_BEGIN();
        Element_ThisIsAList();
    FILLING_END();
}

//---------------------------------------------------------------------------
void File_Vc3::TimeCode()
{
    //Parsing
    Element_Begin1("Time Code");
    bool TCP;

    BS_Begin();
    Get_SB (   TCP,                                             "TCP: Time Code Present");
    Mark_0();
    Mark_0();
    Mark_0();
    Mark_0();
    Mark_0();
    Mark_0();
    Mark_0();
    BS_End();

    if (TCP)
    {
        Skip_B8(                                                "Time Code");
    }
    else
        Skip_B8(                                                "Junk");

    Element_End0();
}

//---------------------------------------------------------------------------
void File_Aac::Read_Buffer_Continue_raw_data_block()
{
    if (Frame_Count>Frame_Count_Valid)
    {
        Skip_XX(Element_Size,                                   "Data");
        return; //Parsing completely only the 1st frame
    }

    BS_Begin();
    raw_data_block();
    BS_End();
    if (FrameIsAlwaysComplete && Element_Offset<Element_Size)
        Skip_XX(Element_Size-Element_Offset,                    "Unknown");

    FILLING_BEGIN();
        //Counting
        Frame_Count++;
        if (Frame_Count_NotParsedIncluded!=(int64u)-1)
            Frame_Count_NotParsedIncluded++;
        Element_Info1(Ztring::ToZtring(Frame_Count));

        //Filling
        if (!Status[IsAccepted])
            File__Analyze::Accept();
        if (Frame_Count>=Frame_Count_Valid)
        {
            //No more need data
            if (Mode==Mode_LATM)
                File__Analyze::Accept();
            File__Analyze::Finish();
        }
    FILLING_END();
}

//---------------------------------------------------------------------------
void File_DvbSubtitle::page_composition_segment()
{
    Element_Name("page composition segment");

    //Parsing
    Skip_B1(                                                    "page_time_out");
    BS_Begin();
    Skip_S1(4,                                                  "page_version_number");
    Skip_S1(2,                                                  "page_state");
    Skip_S1(2,                                                  "reserved");
    BS_End();
    while(Element_Offset<Element_Size)
    {
        Element_Begin1("Region");
        int16u region_horizontal_address, region_vertical_address;
        int8u region_id;
        Get_B1 (region_id,                                      "region_id");
        Skip_B1(                                                "reserved");
        Get_B2 (region_horizontal_address,                      "region_horizontal_address");
        Get_B2 (region_vertical_address,                        "region_vertical_address");
        Element_End0();

        FILLING_BEGIN();
            subtitle_streams[subtitle_stream_id].pages[page_id].regions[region_id].page_composition_segment=true;
            subtitle_streams[subtitle_stream_id].pages[page_id].regions[region_id].region_horizontal_address=region_horizontal_address;
            subtitle_streams[subtitle_stream_id].pages[page_id].regions[region_id].region_vertical_address=region_vertical_address;
        FILLING_END();
    }
}

//---------------------------------------------------------------------------
void File_Tak::ENCODERINFO()
{
    //Parsing
    int8u Revision, Minor, Major, Preset_hi, Preset_lo;
    Get_L1 (Revision,                                           "Revision");
    Get_L1 (Minor,                                              "Minor");
    Get_L1 (Major,                                              "Major");
    BS_Begin();
    Get_S1 (4, Preset_hi,                                       "Preset (hi)");
    Get_S1 (4, Preset_lo,                                       "Preset (lo)");
    BS_End();

    FILLING_BEGIN();
        Ztring Version=Ztring::ToZtring(Major)+__T('.')+Ztring::ToZtring(Minor)+__T('.')+Ztring::ToZtring(Revision);
        Ztring Preset=__T("-p")+Ztring::ToZtring(Preset_lo);
        switch (Preset_hi)
        {
            case 0x00 :                 break;
            case 0x01 : Preset+=__T('e'); break;
            case 0x02 : Preset+=__T('m'); break;
            default   : Preset+=__T('-')+Ztring::ToZtring(Preset_hi, 16); //Unknown
        }

        Fill(Stream_Audio, 0, Audio_Encoded_Library, "TAK");
        Fill(Stream_Audio, 0, Audio_Encoded_Library_String, __T("TAK ")+Version);
        Fill(Stream_Audio, 0, Audio_Encoded_Library_Name, "TAK");
        Fill(Stream_Audio, 0, Audio_Encoded_Library_Version, Version);
        Fill(Stream_Audio, 0, Audio_Encoded_Library_Settings, Preset);
    FILLING_END();
}

//---------------------------------------------------------------------------
void File_Als::FileHeader_Parse()
{
    //Parsing
    int32u SampleRate, Samples;
    int16u Channels;
    int8u BitsPerSample, FileType;
    Skip_C4(                                                    "signature");
    Get_B4 (SampleRate,                                         "sample rate");
    Get_B4 (Samples,                                            "samples");
    Get_B2 (Channels,                                           "channels-1"); Param_Info2(Channels+1, " channel(s)");
    BS_Begin();
    Get_S1 (3, FileType,                                        "file type"); // WAV, RIFF, AIFF
    Get_S1 (3, BitsPerSample,                                   "bits per sample"); Param_Info2((BitsPerSample+1)*8, " bits");
    Skip_SB(                                                    "floating point");
    Skip_SB(                                                    "samples are big-endian");
    BS_End();

    FILLING_BEGIN();
        if (!CalcDurationUncompressedSize(Samples, SampleRate, (BitsPerSample+1)*8, Channels))
            return;

        File__Tags_Helper::Accept("ALS");

        File__Tags_Helper::Stream_Prepare(Stream_Audio);
        Fill(Stream_Audio, 0, Audio_Format, "ALS");
        Fill(Stream_Audio, 0, Audio_Codec, "ALS");
        Fill(Stream_Audio, 0, Audio_BitDepth, (BitsPerSample+1)*8);
        Fill(Stream_Audio, StreamPos_Last, Audio_Channel_s_, Channels+1);
        Fill(Stream_Audio, StreamPos_Last, Audio_SamplingRate, SampleRate);
        Fill(Stream_Audio, 0, Audio_Duration, Duration);

        //No more need data
        File__Tags_Helper::Finish("ALS");
    FILLING_END();
}