/*
The MIT License (MIT)

Copyright (c) 2013-2017 SRS(ossrs)

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_KERNEL_CODEC_HPP
#define SRS_KERNEL_CODEC_HPP

/*
#include <srs_kernel_codec.hpp>
*/

#include <srs_core.hpp>

#include <string>

class SrsBuffer;

/**
 * The video codec id.
 * @doc video_file_format_spec_v10_1.pdf, page78, E.4.3.1 VIDEODATA
 * CodecID UB [4]
 * Codec Identifier. The following values are defined for FLV:
 *      2 = Sorenson H.263
 *      3 = Screen video
 *      4 = On2 VP6
 *      5 = On2 VP6 with alpha channel
 *      6 = Screen video version 2
 *      7 = AVC
 */
enum SrsVideoCodecId
{
    // set to the zero to reserved, for array map.
    SrsVideoCodecIdReserved = 0,
    SrsVideoCodecIdForbidden = 0,
    SrsVideoCodecIdReserved1 = 1,
    SrsVideoCodecIdReserved2 = 9,
    
    // for user to disable video, for example, use pure audio hls.
    SrsVideoCodecIdDisabled = 8,
    
    SrsVideoCodecIdSorensonH263 = 2,
    SrsVideoCodecIdScreenVideo = 3,
    SrsVideoCodecIdOn2VP6 = 4,
    SrsVideoCodecIdOn2VP6WithAlphaChannel = 5,
    SrsVideoCodecIdScreenVideoVersion2 = 6,
    SrsVideoCodecIdAVC = 7,
};
std::string srs_video_codec_id2str(SrsVideoCodecId codec);

/**
 * The video AVC frame trait(characteristic).
 * @doc video_file_format_spec_v10_1.pdf, page79, E.4.3.2 AVCVIDEOPACKET
 * AVCPacketType IF CodecID == 7 UI8
 * The following values are defined:
 *      0 = AVC sequence header
 *      1 = AVC NALU
 *      2 = AVC end of sequence (lower level NALU sequence ender is not required or supported)
 */
enum SrsVideoAvcFrameTrait
{
    // set to the max value to reserved, for array map.
    SrsVideoAvcFrameTraitReserved = 3,
    SrsVideoAvcFrameTraitForbidden = 3,
    
    SrsVideoAvcFrameTraitSequenceHeader = 0,
    SrsVideoAvcFrameTraitNALU = 1,
    SrsVideoAvcFrameTraitSequenceHeaderEOF = 2,
};

/**
 * The video AVC frame type, such as I/P/B.
 * @doc video_file_format_spec_v10_1.pdf, page78, E.4.3.1 VIDEODATA
 * Frame Type UB [4]
 * Type of video frame. The following values are defined:
 *      1 = key frame (for AVC, a seekable frame)
 *      2 = inter frame (for AVC, a non-seekable frame)
 *      3 = disposable inter frame (H.263 only)
 *      4 = generated key frame (reserved for server use only)
 *      5 = video info/command frame
 */
enum SrsVideoAvcFrameType
{
    // set to the zero to reserved, for array map.
    SrsVideoAvcFrameTypeReserved = 0,
    SrsVideoAvcFrameTypeForbidden = 0,
    SrsVideoAvcFrameTypeReserved1 = 6,
    
    SrsVideoAvcFrameTypeKeyFrame = 1,
    SrsVideoAvcFrameTypeInterFrame = 2,
    SrsVideoAvcFrameTypeDisposableInterFrame = 3,
    SrsVideoAvcFrameTypeGeneratedKeyFrame = 4,
    SrsVideoAvcFrameTypeVideoInfoFrame = 5,
};

/**
 * The audio codec id.
 * @doc video_file_format_spec_v10_1.pdf, page 76, E.4.2 Audio Tags
 * SoundFormat UB [4]
 * Format of SoundData. The following values are defined:
 *     0 = Linear PCM, platform endian
 *     1 = ADPCM
 *     2 = MP3
 *     3 = Linear PCM, little endian
 *     4 = Nellymoser 16 kHz mono
 *     5 = Nellymoser 8 kHz mono
 *     6 = Nellymoser
 *     7 = G.711 A-law logarithmic PCM
 *     8 = G.711 mu-law logarithmic PCM
 *     9 = reserved
 *     10 = AAC
 *     11 = Speex
 *     14 = MP3 8 kHz
 *     15 = Device-specific sound
 * Formats 7, 8, 14, and 15 are reserved.
 * AAC is supported in Flash Player 9,0,115,0 and higher.
 * Speex is supported in Flash Player 10 and higher.
 */
enum SrsAudioCodecId
{
    // set to the max value to reserved, for array map.
    SrsAudioCodecIdReserved1 = 16,
    SrsAudioCodecIdForbidden = 16,
    
    // for user to disable audio, for example, use pure video hls.
    SrsAudioCodecIdDisabled = 17,
    
    SrsAudioCodecIdLinearPCMPlatformEndian = 0,
    SrsAudioCodecIdADPCM = 1,
    SrsAudioCodecIdMP3 = 2,
    SrsAudioCodecIdLinearPCMLittleEndian = 3,
    SrsAudioCodecIdNellymoser16kHzMono = 4,
    SrsAudioCodecIdNellymoser8kHzMono = 5,
    SrsAudioCodecIdNellymoser = 6,
    SrsAudioCodecIdReservedG711AlawLogarithmicPCM = 7,
    SrsAudioCodecIdReservedG711MuLawLogarithmicPCM = 8,
    SrsAudioCodecIdReserved = 9,
    SrsAudioCodecIdAAC = 10,
    SrsAudioCodecIdSpeex = 11,
    SrsAudioCodecIdReservedMP3_8kHz = 14,
    SrsAudioCodecIdReservedDeviceSpecificSound = 15,
};
std::string srs_audio_codec_id2str(SrsAudioCodecId codec);

/**
 * The audio AAC frame trait(characteristic).
 * @doc video_file_format_spec_v10_1.pdf, page 77, E.4.2 Audio Tags
 * AACPacketType IF SoundFormat == 10 UI8
 * The following values are defined:
 *      0 = AAC sequence header
 *      1 = AAC raw
 */
enum SrsAudioAacFrameTrait
{
    // set to the max value to reserved, for array map.
    SrsAudioAacFrameTraitReserved = 2,
    SrsAudioAacFrameTraitForbidden = 2,
    
    SrsAudioAacFrameTraitSequenceHeader = 0,
    SrsAudioAacFrameTraitRawData = 1,
};

/**
 * The audio sample rate.
 * @see srs_flv_srates and srs_aac_srates.
 * @doc video_file_format_spec_v10_1.pdf, page 76, E.4.2 Audio Tags
 *      0 = 5.5 kHz = 5512 Hz
 *      1 = 11 kHz = 11025 Hz
 *      2 = 22 kHz = 22050 Hz
 *      3 = 44 kHz = 44100 Hz
 * However, we can extends this table.
 */
enum SrsAudioSampleRate
{
    // set to the max value to reserved, for array map.
    SrsAudioSampleRateReserved = 4,
    SrsAudioSampleRateForbidden = 4,
    
    SrsAudioSampleRate5512 = 0,
    SrsAudioSampleRate11025 = 1,
    SrsAudioSampleRate22050 = 2,
    SrsAudioSampleRate44100 = 3,
};
std::string srs_audio_sample_rate2str(SrsAudioSampleRate v);

/**
 * The frame type, for example, audio, video or data.
 * @doc video_file_format_spec_v10_1.pdf, page 75, E.4.1 FLV Tag
 */
enum SrsFrameType
{
    // set to the zero to reserved, for array map.
    SrsFrameTypeReserved = 0,
    SrsFrameTypeForbidden = 0,

    // 8 = audio
    SrsFrameTypeAudio = 8,
    // 9 = video
    SrsFrameTypeVideo = 9,
    // 18 = script data
    SrsFrameTypeScript = 18,
};

/**
 * Fast tough the codec of FLV video.
 * @doc video_file_format_spec_v10_1.pdf, page 78, E.4.3 Video Tags
 */
class SrsFlvVideo
{
public:
    SrsFlvVideo();
    virtual ~SrsFlvVideo();
// the following function used to finger out the flv/rtmp packet detail.
public:
    /**
    * only check the frame_type, not check the codec type.
    */
    static bool keyframe(char* data, int size);
    /**
    * check codec h264, keyframe, sequence header
    */
    static bool sh(char* data, int size);
    /**
    * check codec h264.
    */
    static bool h264(char* data, int size);
    /**
     * check the video RTMP/flv header info,
     * @return true if video RTMP/flv header is ok.
     * @remark all type of audio is possible, no need to check audio.
     */
    static bool acceptable(char* data, int size);
};

/**
 * Fast tough the codec of FLV video.
 * @doc video_file_format_spec_v10_1.pdf, page 76, E.4.2 Audio Tags
 */
class SrsFlvAudio
{
public:
    SrsFlvAudio();
    virtual ~SrsFlvAudio();
// the following function used to finger out the flv/rtmp packet detail.
public:
    /**
     * check codec aac, sequence header
     */
    static bool sh(char* data, int size);
    /**
     * check codec aac.
     */
    static bool aac(char* data, int size);
};

/**
* the public data, event HLS disable, others can use it.
*/
/**
* the flv sample rate map
*/
extern int srs_flv_srates[];

/**
* the aac sample rate map
*/
extern int srs_aac_srates[];

// The impossible aac sample rate index.
#define SrsAacSampleRateUnset 15

// The max number of NALUs in a video, or aac frame in audio packet.
#define SrsMaxNbSamples 256

/**
 * The audio sample size in bits.
 * @doc video_file_format_spec_v10_1.pdf, page 76, E.4.2 Audio Tags
 * Size of each audio sample. This parameter only pertains to
 * uncompressed formats. Compressed formats always decode
 * to 16 bits internally.
 *      0 = 8-bit samples
 *      1 = 16-bit samples
 */
enum SrsAudioSampleBits
{
    // set to the max value to reserved, for array map.
    SrsAudioSampleBitsReserved = 2,
    SrsAudioSampleBitsForbidden = 2,
    
    SrsAudioSampleBits8bit = 0,
    SrsAudioSampleBits16bit = 1,
};
std::string srs_audio_sample_bits2str(SrsAudioSampleBits v);

/**
 * The audio channels.
 * @doc video_file_format_spec_v10_1.pdf, page 77, E.4.2 Audio Tags
 * Mono or stereo sound
 *      0 = Mono sound
 *      1 = Stereo sound
 */
enum SrsAudioChannels
{
    // set to the max value to reserved, for array map.
    SrsAudioChannelsReserved = 2,
    SrsAudioChannelsForbidden = 2,
    
    SrsAudioChannelsMono = 0,
    SrsAudioChannelsStereo = 1,
};
std::string srs_audio_channels2str(SrsAudioChannels v);

/**
 * Table 7-1 - NAL unit type codes, syntax element categories, and NAL unit type classes
 * ISO_IEC_14496-10-AVC-2012.pdf, page 83.
 */
enum SrsAvcNaluType
{
    // Unspecified
    SrsAvcNaluTypeReserved = 0,
    SrsAvcNaluTypeForbidden = 0,
    
    // Coded slice of a non-IDR picture slice_layer_without_partitioning_rbsp( )
    SrsAvcNaluTypeNonIDR = 1,
    // Coded slice data partition A slice_data_partition_a_layer_rbsp( )
    SrsAvcNaluTypeDataPartitionA = 2,
    // Coded slice data partition B slice_data_partition_b_layer_rbsp( )
    SrsAvcNaluTypeDataPartitionB = 3,
    // Coded slice data partition C slice_data_partition_c_layer_rbsp( )
    SrsAvcNaluTypeDataPartitionC = 4,
    // Coded slice of an IDR picture slice_layer_without_partitioning_rbsp( )
    SrsAvcNaluTypeIDR = 5,
    // Supplemental enhancement information (SEI) sei_rbsp( )
    SrsAvcNaluTypeSEI = 6,
    // Sequence parameter set seq_parameter_set_rbsp( )
    SrsAvcNaluTypeSPS = 7,
    // Picture parameter set pic_parameter_set_rbsp( )
    SrsAvcNaluTypePPS = 8,
    // Access unit delimiter access_unit_delimiter_rbsp( )
    SrsAvcNaluTypeAccessUnitDelimiter = 9,
    // End of sequence end_of_seq_rbsp( )
    SrsAvcNaluTypeEOSequence = 10,
    // End of stream end_of_stream_rbsp( )
    SrsAvcNaluTypeEOStream = 11,
    // Filler data filler_data_rbsp( )
    SrsAvcNaluTypeFilterData = 12,
    // Sequence parameter set extension seq_parameter_set_extension_rbsp( )
    SrsAvcNaluTypeSPSExt = 13,
    // Prefix NAL unit prefix_nal_unit_rbsp( )
    SrsAvcNaluTypePrefixNALU = 14,
    // Subset sequence parameter set subset_seq_parameter_set_rbsp( )
    SrsAvcNaluTypeSubsetSPS = 15,
    // Coded slice of an auxiliary coded picture without partitioning slice_layer_without_partitioning_rbsp( )
    SrsAvcNaluTypeLayerWithoutPartition = 19,
    // Coded slice extension slice_layer_extension_rbsp( )
    SrsAvcNaluTypeCodedSliceExt = 20,
};
std::string srs_avc_nalu2str(SrsAvcNaluType nalu_type);

/**
 * the avc payload format, must be ibmf or annexb format.
 * we guess by annexb first, then ibmf for the first time,
 * and we always use the guessed format for the next time.
 */
enum SrsAvcPayloadFormat
{
    SrsAvcPayloadFormatGuess = 0,
    SrsAvcPayloadFormatAnnexb,
    SrsAvcPayloadFormatIbmf,
};

/**
 * the aac profile, for ADTS(HLS/TS)
 * @see https://github.com/ossrs/srs/issues/310
 */
enum SrsAacProfile
{
    SrsAacProfileReserved = 3,
    
    // @see 7.1 Profiles, aac-iso-13818-7.pdf, page 40
    SrsAacProfileMain = 0,
    SrsAacProfileLC = 1,
    SrsAacProfileSSR = 2,
};
std::string srs_aac_profile2str(SrsAacProfile aac_profile);

/**
 * the aac object type, for RTMP sequence header
 * for AudioSpecificConfig, @see ISO_IEC_14496-3-AAC-2001.pdf, page 33
 * for audioObjectType, @see ISO_IEC_14496-3-AAC-2001.pdf, page 23
 */
enum SrsAacObjectType
{
    SrsAacObjectTypeReserved = 0,
    SrsAacObjectTypeForbidden = 0,
    
    // Table 1.1 - Audio Object Type definition
    // @see @see ISO_IEC_14496-3-AAC-2001.pdf, page 23
    SrsAacObjectTypeAacMain = 1,
    SrsAacObjectTypeAacLC = 2,
    SrsAacObjectTypeAacSSR = 3,
    
    // AAC HE = LC+SBR
    SrsAacObjectTypeAacHE = 5,
    // AAC HEv2 = LC+SBR+PS
    SrsAacObjectTypeAacHEV2 = 29,
};
std::string srs_aac_object2str(SrsAacObjectType aac_object);
// ts/hls/adts audio header profile to RTMP sequence header object type.
SrsAacObjectType srs_aac_ts2rtmp(SrsAacProfile profile);
// RTMP sequence header object type to ts/hls/adts audio header profile.
SrsAacProfile srs_aac_rtmp2ts(SrsAacObjectType object_type);

/**
 * the profile for avc/h.264.
 * @see Annex A Profiles and levels, ISO_IEC_14496-10-AVC-2003.pdf, page 205.
 */
enum SrsAvcProfile
{
    SrsAvcProfileReserved = 0,
    
    // @see ffmpeg, libavcodec/avcodec.h:2713
    SrsAvcProfileBaseline = 66,
    // FF_PROFILE_H264_CONSTRAINED  (1<<9)  // 8+1; constraint_set1_flag
    // FF_PROFILE_H264_CONSTRAINED_BASELINE (66|FF_PROFILE_H264_CONSTRAINED)
    SrsAvcProfileConstrainedBaseline = 578,
    SrsAvcProfileMain = 77,
    SrsAvcProfileExtended = 88,
    SrsAvcProfileHigh = 100,
    SrsAvcProfileHigh10 = 110,
    SrsAvcProfileHigh10Intra = 2158,
    SrsAvcProfileHigh422 = 122,
    SrsAvcProfileHigh422Intra = 2170,
    SrsAvcProfileHigh444 = 144,
    SrsAvcProfileHigh444Predictive = 244,
    SrsAvcProfileHigh444Intra = 2192,
};
std::string srs_avc_profile2str(SrsAvcProfile profile);

/**
 * the level for avc/h.264.
 * @see Annex A Profiles and levels, ISO_IEC_14496-10-AVC-2003.pdf, page 207.
 */
enum SrsAvcLevel
{
    SrsAvcLevelReserved = 0,
    
    SrsAvcLevel_1 = 10,
    SrsAvcLevel_11 = 11,
    SrsAvcLevel_12 = 12,
    SrsAvcLevel_13 = 13,
    SrsAvcLevel_2 = 20,
    SrsAvcLevel_21 = 21,
    SrsAvcLevel_22 = 22,
    SrsAvcLevel_3 = 30,
    SrsAvcLevel_31 = 31,
    SrsAvcLevel_32 = 32,
    SrsAvcLevel_4 = 40,
    SrsAvcLevel_41 = 41,
    SrsAvcLevel_5 = 50,
    SrsAvcLevel_51 = 51,
};
std::string srs_avc_level2str(SrsAvcLevel level);

/**
 * A sample is the unit of frame.
 * It's a NALU for H.264.
 * It's the whole AAC raw data for AAC.
 * @remark Neither SPS/PPS or ASC is sample unit, it's codec sequence header.
 */
class SrsSample
{
public:
    // The size of unit.
    int size;
    // The ptr of unit, user must manage it.
    char* bytes;
public:
    SrsSample();
    virtual ~SrsSample();
};

/**
 * The codec is the information of encoder,
 * corresponding to the sequence header of FLV,
 * parsed to detail info.
 */
class SrsCodecConfig
{
public:
    SrsCodecConfig();
    virtual ~SrsCodecConfig();
};

/**
 * The audio codec info.
 */
class SrsAudioCodecConfig : public SrsCodecConfig
{
// In FLV specification.
public:
    // audio specified
    SrsAudioCodecId id;
    // audio aac specified.
    SrsAudioSampleRate sound_rate;
    SrsAudioSampleBits sound_size;
    // TODO: FIXME: Rename to sound_channels.
    SrsAudioChannels sound_type;
    int audio_data_rate; // in bps
// In AAC specification.
public:
    /**
     * audio specified
     * audioObjectType, in 1.6.2.1 AudioSpecificConfig, page 33,
     * 1.5.1.1 Audio object type definition, page 23,
     *           in ISO_IEC_14496-3-AAC-2001.pdf.
     */
    SrsAacObjectType aac_object;
    /**
     * samplingFrequencyIndex
     */
    uint8_t aac_sample_rate;
    /**
     * channelConfiguration
     */
    uint8_t aac_channels;
// Sequence header payload.
public:
    /**
     * the aac extra data, the AAC sequence header,
     * without the flv codec header,
     * @see: ffmpeg, AVCodecContext::extradata
     */
    int aac_extra_size;
    char* aac_extra_data;
public:
    SrsAudioCodecConfig();
    virtual ~SrsAudioCodecConfig();
public:
    virtual bool is_aac_codec_ok();
};

/**
 * The video codec info.
 */
class SrsVideoCodecConfig : public SrsCodecConfig
{
public:
    SrsVideoCodecId id;
    int video_data_rate; // in bps
    double frame_rate;
    double duration;
    int width;
    int height;
public:
    /**
     * the avc extra data, the AVC sequence header,
     * without the flv codec header,
     * @see: ffmpeg, AVCodecContext::extradata
     */
    int avc_extra_size;
    char* avc_extra_data;
public:
    /**
     * video specified
     */
    // profile_idc, ISO_IEC_14496-10-AVC-2003.pdf, page 45.
    SrsAvcProfile avc_profile;
    // level_idc, ISO_IEC_14496-10-AVC-2003.pdf, page 45.
    SrsAvcLevel avc_level;
    // lengthSizeMinusOne, ISO_IEC_14496-15-AVC-format-2012.pdf, page 16
    int8_t NAL_unit_length;
    uint16_t sequenceParameterSetLength;
    char* sequenceParameterSetNALUnit;
    uint16_t pictureParameterSetLength;
    char* pictureParameterSetNALUnit;
public:
    // the avc payload format.
    SrsAvcPayloadFormat payload_format;
public:
    SrsVideoCodecConfig();
    virtual ~SrsVideoCodecConfig();
public:
    virtual bool is_avc_codec_ok();
};

/**
 * A frame, consists of a codec and a group of samples.
 */
class SrsFrame
{
public:
    // The DTS/PTS in milliseconds, which is TBN=1000.
    int64_t dts;
    // PTS = DTS + CTS.
    int32_t cts;
public:
    // The codec info of frame.
    SrsCodecConfig* codec;
    // The actual parsed number of samples.
    int nb_samples;
    // The sampels cache.
    SrsSample samples[SrsMaxNbSamples];
public:
    SrsFrame();
    virtual ~SrsFrame();
public:
    // Initialize the frame, to parse sampels.
    virtual int initialize(SrsCodecConfig* c);
    // Add a sample to frame.
    virtual int add_sample(char* bytes, int size);
};

/**
 * A audio frame, besides a frame, contains the audio frame info, such as frame type.
 */
class SrsAudioFrame : public SrsFrame
{
public:
    SrsAudioAacFrameTrait aac_packet_type;
public:
    SrsAudioFrame();
    virtual ~SrsAudioFrame();
public:
    virtual SrsAudioCodecConfig* acodec();
};

/**
 * A video frame, besides a frame, contains the video frame info, such as frame type.
 */
class SrsVideoFrame : public SrsFrame
{
public:
    // video specified
    SrsVideoAvcFrameType frame_type;
    SrsVideoAvcFrameTrait avc_packet_type;
    // whether sample_units contains IDR frame.
    bool has_idr;
    // Whether exists AUD NALU.
    bool has_aud;
    // Whether exists SPS/PPS NALU.
    bool has_sps_pps;
    // The first nalu type.
    SrsAvcNaluType first_nalu_type;
public:
    SrsVideoFrame();
    virtual ~SrsVideoFrame();
public:
    // Add the sample without ANNEXB or IBMF header, or RAW AAC or MP3 data.
    virtual int add_sample(char* bytes, int size);
public:
    virtual SrsVideoCodecConfig* vcodec();
};

/**
 * A codec format, including one or many stream, each stream identified by a frame.
 * For example, a typical RTMP stream format, consits of a video and audio frame.
 * Maybe some RTMP stream only has a audio stream, for instance, redio application.
 */
class SrsFormat
{
public:
    SrsAudioFrame* audio;
    SrsAudioCodecConfig* acodec;
    SrsVideoFrame* video;
    SrsVideoCodecConfig* vcodec;
    SrsBuffer* buffer;
public:
    // for sequence header, whether parse the h.264 sps.
    // TODO: FIXME: Refine it.
    bool            avc_parse_sps;
public:
    SrsFormat();
    virtual ~SrsFormat();
public:
    // Initialize the format.
    virtual int initialize();
    // When got a parsed audio packet.
    // @param data The data in FLV format.
    virtual int on_audio(int64_t timestamp, char* data, int size);
    // When got a parsed video packet.
    // @param data The data in FLV format.
    virtual int on_video(int64_t timestamp, char* data, int size);
    // When got a audio aac sequence header.
    virtual int on_aac_sequence_header(char* data, int size);
public:
    virtual bool is_aac_sequence_header();
    virtual bool is_avc_sequence_header();
private:
    // Demux the video packet in H.264 codec.
    // The packet is muxed in FLV format, defined in flv specification.
    //          Demux the sps/pps from sequence header.
    //          Demux the samples from NALUs.
    virtual int video_avc_demux(SrsBuffer* stream, int64_t timestamp);
private:
    // Parse the H.264 SPS/PPS.
    virtual int avc_demux_sps_pps(SrsBuffer* stream);
    virtual int avc_demux_sps();
    virtual int avc_demux_sps_rbsp(char* rbsp, int nb_rbsp);
private:
    // Parse the H.264 NALUs.
    virtual int video_nalu_demux(SrsBuffer* stream);
    // Demux the avc NALU in "AnnexB" from ISO_IEC_14496-10-AVC-2003.pdf, page 211.
    virtual int avc_demux_annexb_format(SrsBuffer* stream);
    // Demux the avc NALU in "ISO Base Media File Format" from ISO_IEC_14496-15-AVC-format-2012.pdf, page 20
    virtual int avc_demux_ibmf_format(SrsBuffer* stream);
private:
    // Demux the audio packet in AAC codec.
    //          Demux the asc from sequence header.
    //          Demux the sampels from RAW data.
    virtual int audio_aac_demux(SrsBuffer* stream, int64_t timestamp);
    virtual int audio_mp3_demux(SrsBuffer* stream, int64_t timestamp);
public:
    // Directly demux the sequence header, without RTMP packet header.
    virtual int audio_aac_sequence_header_demux(char* data, int size);
};

#endif