srs/trunk/src/kernel/srs_kernel_codec.cpp

/*
The MIT License (MIT)

Copyright (c) 2013-2015 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_codec.hpp>

#include <string.h>
#include <stdlib.h>
using namespace std;

#include <srs_kernel_error.hpp>
#include <srs_kernel_log.hpp>
#include <srs_kernel_stream.hpp>
#include <srs_kernel_utility.hpp>

SrsFlvCodec::SrsFlvCodec()
{
}

SrsFlvCodec::~SrsFlvCodec()
{
}

bool SrsFlvCodec::video_is_keyframe(char* data, int size)
{
    // 2bytes required.
    if (size < 1) {
        return false;
    }

    char frame_type = data[0];
    frame_type = (frame_type >> 4) & 0x0F;
    
    return frame_type == SrsCodecVideoAVCFrameKeyFrame;
}

bool SrsFlvCodec::video_is_sequence_header(char* data, int size)
{
    // sequence header only for h264
    if (!video_is_h264(data, size)) {
        return false;
    }
    
    // 2bytes required.
    if (size < 2) {
        return false;
    }

    char frame_type = data[0];
    frame_type = (frame_type >> 4) & 0x0F;

    char avc_packet_type = data[1];
    
    return frame_type == SrsCodecVideoAVCFrameKeyFrame 
        && avc_packet_type == SrsCodecVideoAVCTypeSequenceHeader;
}

bool SrsFlvCodec::audio_is_sequence_header(char* data, int size)
{
    // sequence header only for aac
    if (!audio_is_aac(data, size)) {
        return false;
    }
    
    // 2bytes required.
    if (size < 2) {
        return false;
    }
    
    char aac_packet_type = data[1];
    
    return aac_packet_type == SrsCodecAudioTypeSequenceHeader;
}

bool SrsFlvCodec::video_is_h264(char* data, int size)
{
    // 1bytes required.
    if (size < 1) {
        return false;
    }

    char codec_id = data[0];
    codec_id = codec_id & 0x0F;
    
    return codec_id == SrsCodecVideoAVC;
}

bool SrsFlvCodec::audio_is_aac(char* data, int size)
{
    // 1bytes required.
    if (size < 1) {
        return false;
    }
    
    char sound_format = data[0];
    sound_format = (sound_format >> 4) & 0x0F;
    
    return sound_format == SrsCodecAudioAAC;
}

SrsCodecSampleUnit::SrsCodecSampleUnit()
{
    size = 0;
    bytes = NULL;
}

SrsCodecSampleUnit::~SrsCodecSampleUnit()
{
}

SrsCodecSample::SrsCodecSample()
{
    clear();
}

SrsCodecSample::~SrsCodecSample()
{
}

void SrsCodecSample::clear()
{
    is_video = false;
    nb_sample_units = 0;

    cts = 0;
    frame_type = SrsCodecVideoAVCFrameReserved;
    avc_packet_type = SrsCodecVideoAVCTypeReserved;
    
    acodec = SrsCodecAudioReserved1;
    sound_rate = SrsCodecAudioSampleRateReserved;
    sound_size = SrsCodecAudioSampleSizeReserved;
    sound_type = SrsCodecAudioSoundTypeReserved;
    aac_packet_type = SrsCodecAudioTypeReserved;
}

int SrsCodecSample::add_sample_unit(char* bytes, int size)
{
    int ret = ERROR_SUCCESS;
    
    if (nb_sample_units >= __SRS_SRS_MAX_CODEC_SAMPLE) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("hls decode samples error, "
            "exceed the max count: %d, ret=%d", __SRS_SRS_MAX_CODEC_SAMPLE, ret);
        return ret;
    }
    
    SrsCodecSampleUnit* sample_unit = &sample_units[nb_sample_units++];
    sample_unit->bytes = bytes;
    sample_unit->size = size;
    
    return ret;
}

SrsAvcAacCodec::SrsAvcAacCodec()
{
    width                       = 0;
    height                      = 0;
    duration                    = 0;
    NAL_unit_length             = 0;
    frame_rate                  = 0;

    video_data_rate             = 0;
    video_codec_id              = 0;

    audio_data_rate             = 0;
    audio_codec_id              = 0;

    avc_profile                 = 0;
    avc_level                   = 0;
    aac_profile                 = 0;
    aac_sample_rate             = __SRS_AAC_SAMPLE_RATE_UNSET; // sample rate ignored
    aac_channels                = 0;
    avc_extra_size              = 0;
    avc_extra_data              = NULL;
    aac_extra_size              = 0;
    aac_extra_data              = NULL;

    sequenceParameterSetLength  = 0;
    sequenceParameterSetNALUnit = NULL;
    pictureParameterSetLength   = 0;
    pictureParameterSetNALUnit  = NULL;

    payload_format = SrsAvcPayloadFormatGuess;
    stream = new SrsStream();
}

SrsAvcAacCodec::~SrsAvcAacCodec()
{
    srs_freep(avc_extra_data);
    srs_freep(aac_extra_data);

    srs_freep(stream);
    srs_freep(sequenceParameterSetNALUnit);
    srs_freep(pictureParameterSetNALUnit);
}

int SrsAvcAacCodec::audio_aac_demux(char* data, int size, SrsCodecSample* sample)
{
    int ret = ERROR_SUCCESS;
    
    sample->is_video = false;
    
    if (!data || size <= 0) {
        srs_trace("no audio present, ignore it.");
        return ret;
    }
    
    if ((ret = stream->initialize(data, size)) != ERROR_SUCCESS) {
        return ret;
    }

    // audio decode
    if (!stream->require(1)) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("audio codec decode sound_format failed. ret=%d", ret);
        return ret;
    }
    
    // @see: E.4.2 Audio Tags, video_file_format_spec_v10_1.pdf, page 76
    int8_t sound_format = stream->read_1bytes();
    
    int8_t sound_type = sound_format & 0x01;
    int8_t sound_size = (sound_format >> 1) & 0x01;
    int8_t sound_rate = (sound_format >> 2) & 0x03;
    sound_format = (sound_format >> 4) & 0x0f;
    
    audio_codec_id = sound_format;
    sample->acodec = (SrsCodecAudio)audio_codec_id;

    sample->sound_type = (SrsCodecAudioSoundType)sound_type;
    sample->sound_rate = (SrsCodecAudioSampleRate)sound_rate;
    sample->sound_size = (SrsCodecAudioSampleSize)sound_size;

    // we support h.264+mp3 for hls.
    if (audio_codec_id == SrsCodecAudioMP3) {
        return ERROR_HLS_TRY_MP3;
    }
    
    // only support aac
    if (audio_codec_id != SrsCodecAudioAAC) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("audio codec only support mp3/aac codec. actual=%d, ret=%d", audio_codec_id, ret);
        return ret;
    }

    if (!stream->require(1)) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("audio codec decode aac_packet_type failed. ret=%d", ret);
        return ret;
    }
    
    int8_t aac_packet_type = stream->read_1bytes();
    sample->aac_packet_type = (SrsCodecAudioType)aac_packet_type;
    
    if (aac_packet_type == SrsCodecAudioTypeSequenceHeader) {
        // AudioSpecificConfig
        // 1.6.2.1 AudioSpecificConfig, in aac-mp4a-format-ISO_IEC_14496-3+2001.pdf, page 33.
        aac_extra_size = stream->size() - stream->pos();
        if (aac_extra_size > 0) {
            srs_freep(aac_extra_data);
            aac_extra_data = new char[aac_extra_size];
            memcpy(aac_extra_data, stream->data() + stream->pos(), aac_extra_size);

            // demux the sequence header.
            if ((ret = audio_aac_sequence_header_demux(aac_extra_data, aac_extra_size)) != ERROR_SUCCESS) {
                return ret;
            }
        }
    } else if (aac_packet_type == SrsCodecAudioTypeRawData) {
        // ensure the sequence header demuxed
        if (aac_extra_size <= 0 || !aac_extra_data) {
            ret = ERROR_HLS_DECODE_ERROR;
            srs_error("audio codec decode aac failed, sequence header not found. ret=%d", ret);
            return ret;
        }
        
        // Raw AAC frame data in UI8 []
        // 6.3 Raw Data, aac-iso-13818-7.pdf, page 28
        if ((ret = sample->add_sample_unit(stream->data() + stream->pos(), stream->size() - stream->pos())) != ERROR_SUCCESS) {
            srs_error("audio codec add sample failed. ret=%d", ret);
            return ret;
        }
    } else {
        // ignored.
    }
    
    // reset the sample rate by sequence header
    if (aac_sample_rate != __SRS_AAC_SAMPLE_RATE_UNSET) {
        static int aac_sample_rates[] = {
            96000, 88200, 64000, 48000,
            44100, 32000, 24000, 22050,
            16000, 12000, 11025,  8000,
            7350,     0,     0,    0
        };
        switch (aac_sample_rates[aac_sample_rate]) {
            case 11025:
                sample->sound_rate = SrsCodecAudioSampleRate11025;
                break;
            case 22050:
                sample->sound_rate = SrsCodecAudioSampleRate22050;
                break;
            case 44100:
                sample->sound_rate = SrsCodecAudioSampleRate44100;
                break;
            default:
                break;
        };
    }
    
    srs_info("audio decoded, type=%d, codec=%d, asize=%d, rate=%d, format=%d, size=%d", 
        sound_type, audio_codec_id, sound_size, sound_rate, sound_format, size);
    
    return ret;
}

int SrsAvcAacCodec::audio_mp3_demux(char* data, int size, SrsCodecSample* sample)
{
    int ret = ERROR_SUCCESS;

    // we always decode aac then mp3.
    srs_assert(sample->acodec == SrsCodecAudioMP3);
    
    // @see: E.4.2 Audio Tags, video_file_format_spec_v10_1.pdf, page 76
    if (!data || size <= 1) {
        srs_trace("no mp3 audio present, ignore it.");
        return ret;
    }

    // mp3 payload.
    if ((ret = sample->add_sample_unit(data + 1, size - 1)) != ERROR_SUCCESS) {
        srs_error("audio codec add mp3 sample failed. ret=%d", ret);
        return ret;
    }
    
    srs_info("audio decoded, type=%d, codec=%d, asize=%d, rate=%d, format=%d, size=%d", 
        sample->sound_type, audio_codec_id, sample->sound_size, sample->sound_rate, sample->acodec, size);
    
    return ret;
}

int SrsAvcAacCodec::audio_aac_sequence_header_demux(char* data, int size)
{
    int ret = ERROR_SUCCESS;
    
    if ((ret = stream->initialize(data, size)) != ERROR_SUCCESS) {
        return ret;
    }
        
    // only need to decode the first 2bytes:
    //      audioObjectType, aac_profile, 5bits.
    //      samplingFrequencyIndex, aac_sample_rate, 4bits.
    //      channelConfiguration, aac_channels, 4bits
    if (!stream->require(2)) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("audio codec decode aac sequence header failed. ret=%d", ret);
        return ret;
    }
    u_int8_t profile_ObjectType = stream->read_1bytes();
    u_int8_t samplingFrequencyIndex = stream->read_1bytes();
        
    aac_channels = (samplingFrequencyIndex >> 3) & 0x0f;
    samplingFrequencyIndex = ((profile_ObjectType << 1) & 0x0e) | ((samplingFrequencyIndex >> 7) & 0x01);
    profile_ObjectType = (profile_ObjectType >> 3) & 0x1f;

    // set the aac sample rate.
    aac_sample_rate = samplingFrequencyIndex;

    // the profile = object_id + 1
    // @see aac-mp4a-format-ISO_IEC_14496-3+2001.pdf, page 78,
    //      Table 1. A.9 <20>C MPEG-2 Audio profiles and MPEG-4 Audio object types
    aac_profile = profile_ObjectType + 1;
        
    // the valid aac profile:
    //      MPEG-2 profile
    //      Main profile (ID == 1)
    //      Low Complexity profile (LC) (ID == 2)
    //      Scalable Sampling Rate profile (SSR) (ID == 3)
    //      (reserved) (ID == 4)
    // @see aac-mp4a-format-ISO_IEC_14496-3+2001.pdf, page 78,
    //      Table 1. A.9 <20>C MPEG-2 Audio profiles and MPEG-4 Audio object types
    if (aac_profile > 4) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("audio codec decode aac sequence header failed, "
            "adts object=%d invalid. ret=%d", profile_ObjectType, ret);
        return ret;
    }
        
    // TODO: FIXME: to support aac he/he-v2, see: ngx_rtmp_codec_parse_aac_header
    // @see: https://github.com/winlinvip/nginx-rtmp-module/commit/3a5f9eea78fc8d11e8be922aea9ac349b9dcbfc2
    // 
    // donot force to LC, @see: https://github.com/winlinvip/simple-rtmp-server/issues/81
    // the source will print the sequence header info.
    //if (aac_profile > 3) {
        // Mark all extended profiles as LC
        // to make Android as happy as possible.
        // @see: ngx_rtmp_hls_parse_aac_header
        //aac_profile = 1;
    //}

    return ret;
}

int SrsAvcAacCodec::video_avc_demux(char* data, int size, SrsCodecSample* sample)
{
    int ret = ERROR_SUCCESS;
    
    sample->is_video = true;
    
    if (!data || size <= 0) {
        srs_trace("no video present, ignore it.");
        return ret;
    }
    
    if ((ret = stream->initialize(data, size)) != ERROR_SUCCESS) {
        return ret;
    }

    // video decode
    if (!stream->require(1)) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("video codec decode frame_type failed. ret=%d", ret);
        return ret;
    }
    
    // @see: E.4.3 Video Tags, video_file_format_spec_v10_1.pdf, page 78
    int8_t frame_type = stream->read_1bytes();
    int8_t codec_id = frame_type & 0x0f;
    frame_type = (frame_type >> 4) & 0x0f;
    
    sample->frame_type = (SrsCodecVideoAVCFrame)frame_type;
    
    // ignore info frame without error,
    // @see https://github.com/winlinvip/simple-rtmp-server/issues/288#issuecomment-69863909
    if (sample->frame_type == SrsCodecVideoAVCFrameVideoInfoFrame) {
        srs_warn("video codec igone the info frame, ret=%d", ret);
        return ret;
    }
    
    // only support h.264/avc
    if (codec_id != SrsCodecVideoAVC) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("video codec only support video h.264/avc codec. actual=%d, ret=%d", codec_id, ret);
        return ret;
    }
    video_codec_id = codec_id;
    
    if (!stream->require(4)) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("video codec decode avc_packet_type failed. ret=%d", ret);
        return ret;
    }
    int8_t avc_packet_type = stream->read_1bytes();
    int32_t composition_time = stream->read_3bytes();
    
    // pts = dts + cts.
    sample->cts = composition_time;
    sample->avc_packet_type = (SrsCodecVideoAVCType)avc_packet_type;
    
    if (avc_packet_type == SrsCodecVideoAVCTypeSequenceHeader) {
        if ((ret = avc_demux_sps_pps(stream)) != ERROR_SUCCESS) {
            return ret;
        }
    } else if (avc_packet_type == SrsCodecVideoAVCTypeNALU){
        // ensure the sequence header demuxed
        if (avc_extra_size <= 0 || !avc_extra_data) {
            ret = ERROR_HLS_DECODE_ERROR;
            srs_error("avc decode failed, sequence header not found. ret=%d", ret);
            return ret;
        }

        // guess for the first time.
        if (payload_format == SrsAvcPayloadFormatGuess) {
            // One or more NALUs (Full frames are required)
            // try  "AnnexB" from H.264-AVC-ISO_IEC_14496-10.pdf, page 211.
            if ((ret = avc_demux_annexb_format(stream, sample)) != ERROR_SUCCESS) {
                // stop try when system error.
                if (ret != ERROR_HLS_AVC_TRY_OTHERS) {
                    srs_error("avc demux for annexb failed. ret=%d", ret);
                    return ret;
                }
                
                // try "ISO Base Media File Format" from H.264-AVC-ISO_IEC_14496-15.pdf, page 20
                if ((ret = avc_demux_ibmf_format(stream, sample)) != ERROR_SUCCESS) {
                    return ret;
                } else {
                    payload_format = SrsAvcPayloadFormatIbmf;
                    srs_info("hls guess avc payload is ibmf format.");
                }
            } else {
                payload_format = SrsAvcPayloadFormatAnnexb;
                srs_info("hls guess avc payload is annexb format.");
            }
        } else if (payload_format == SrsAvcPayloadFormatIbmf) {
            // try "ISO Base Media File Format" from H.264-AVC-ISO_IEC_14496-15.pdf, page 20
            if ((ret = avc_demux_ibmf_format(stream, sample)) != ERROR_SUCCESS) {
                return ret;
            }
            srs_info("hls decode avc payload in ibmf format.");
        } else {
            // One or more NALUs (Full frames are required)
            // try  "AnnexB" from H.264-AVC-ISO_IEC_14496-10.pdf, page 211.
            if ((ret = avc_demux_annexb_format(stream, sample)) != ERROR_SUCCESS) {
                return ret;
            }
            srs_info("hls decode avc payload in annexb format.");
        }
    } else {
        // ignored.
    }
    
    srs_info("video decoded, type=%d, codec=%d, avc=%d, cts=%d, size=%d", 
        frame_type, video_codec_id, avc_packet_type, composition_time, size);
    
    return ret;
}

int SrsAvcAacCodec::avc_demux_sps_pps(SrsStream* stream)
{
    int ret = ERROR_SUCCESS;
    
    // AVCDecoderConfigurationRecord
    // 5.2.4.1.1 Syntax, H.264-AVC-ISO_IEC_14496-15.pdf, page 16
    avc_extra_size = stream->size() - stream->pos();
    if (avc_extra_size > 0) {
        srs_freep(avc_extra_data);
        avc_extra_data = new char[avc_extra_size];
        memcpy(avc_extra_data, stream->data() + stream->pos(), avc_extra_size);
    }
    
    if (!stream->require(6)) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("avc decode sequenc header failed. ret=%d", ret);
        return ret;
    }
    //int8_t configurationVersion = stream->read_1bytes();
    stream->read_1bytes();
    //int8_t AVCProfileIndication = stream->read_1bytes();
    avc_profile = stream->read_1bytes();
    //int8_t profile_compatibility = stream->read_1bytes();
    stream->read_1bytes();
    //int8_t AVCLevelIndication = stream->read_1bytes();
    avc_level = stream->read_1bytes();
    
    // parse the NALU size.
    int8_t lengthSizeMinusOne = stream->read_1bytes();
    lengthSizeMinusOne &= 0x03;
    NAL_unit_length = lengthSizeMinusOne;
    
    // 5.3.4.2.1 Syntax, H.264-AVC-ISO_IEC_14496-15.pdf, page 16
    // 5.2.4.1 AVC decoder configuration record
    // 5.2.4.1.2 Semantics
    // The value of this field shall be one of 0, 1, or 3 corresponding to a
    // length encoded with 1, 2, or 4 bytes, respectively.
    if (NAL_unit_length == 2) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("sps lengthSizeMinusOne should never be 2. ret=%d", ret);
        return ret;
    }
    
    // 1 sps
    if (!stream->require(1)) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("avc decode sequenc header sps failed. ret=%d", ret);
        return ret;
    }
    int8_t numOfSequenceParameterSets = stream->read_1bytes();
    numOfSequenceParameterSets &= 0x1f;
    if (numOfSequenceParameterSets != 1) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("avc decode sequenc header sps failed. ret=%d", ret);
        return ret;
    }
    if (!stream->require(2)) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("avc decode sequenc header sps size failed. ret=%d", ret);
        return ret;
    }
    sequenceParameterSetLength = stream->read_2bytes();
    if (!stream->require(sequenceParameterSetLength)) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("avc decode sequenc header sps data failed. ret=%d", ret);
        return ret;
    }
    if (sequenceParameterSetLength > 0) {
        srs_freep(sequenceParameterSetNALUnit);
        sequenceParameterSetNALUnit = new char[sequenceParameterSetLength];
        memcpy(sequenceParameterSetNALUnit, stream->data() + stream->pos(), sequenceParameterSetLength);
        stream->skip(sequenceParameterSetLength);
    }
    // 1 pps
    if (!stream->require(1)) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("avc decode sequenc header pps failed. ret=%d", ret);
        return ret;
    }
    int8_t numOfPictureParameterSets = stream->read_1bytes();
    numOfPictureParameterSets &= 0x1f;
    if (numOfPictureParameterSets != 1) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("avc decode sequenc header pps failed. ret=%d", ret);
        return ret;
    }
    if (!stream->require(2)) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("avc decode sequenc header pps size failed. ret=%d", ret);
        return ret;
    }
    pictureParameterSetLength = stream->read_2bytes();
    if (!stream->require(pictureParameterSetLength)) {
        ret = ERROR_HLS_DECODE_ERROR;
        srs_error("avc decode sequenc header pps data failed. ret=%d", ret);
        return ret;
    }
    if (pictureParameterSetLength > 0) {
        srs_freep(pictureParameterSetNALUnit);
        pictureParameterSetNALUnit = new char[pictureParameterSetLength];
        memcpy(pictureParameterSetNALUnit, stream->data() + stream->pos(), pictureParameterSetLength);
        stream->skip(pictureParameterSetLength);
    }
    
    return ret;
}

int SrsAvcAacCodec::avc_demux_annexb_format(SrsStream* stream, SrsCodecSample* sample)
{
    int ret = ERROR_SUCCESS;
    
    // not annexb, try others
    if (!srs_avc_startswith_annexb(stream, NULL)) {
        return ERROR_HLS_AVC_TRY_OTHERS;
    }
    
    // AnnexB
    // B.1.1 Byte stream NAL unit syntax,
    // H.264-AVC-ISO_IEC_14496-10.pdf, page 211.
    while (!stream->empty()) {
        // find start code
        int nb_start_code = 0;
        if (!srs_avc_startswith_annexb(stream, &nb_start_code)) {
            return ret;
        }

        // skip the start code.
        if (nb_start_code > 0) {
            stream->skip(nb_start_code);
        }
        
        // the NALU start bytes.
        char* p = stream->data() + stream->pos();
        
        // get the last matched NALU
        while (!stream->empty()) {
            if (srs_avc_startswith_annexb(stream, NULL)) {
                break;
            }
            
            stream->skip(1);
        }
        
        char* pp = stream->data() + stream->pos();
        
        // skip the empty.
        if (pp - p <= 0) {
            continue;
        }
        
        // got the NALU.
        if ((ret = sample->add_sample_unit(p, pp - p)) != ERROR_SUCCESS) {
            srs_error("annexb add video sample failed. ret=%d", ret);
            return ret;
        }
    }
    
    return ret;
}

int SrsAvcAacCodec::avc_demux_ibmf_format(SrsStream* stream, SrsCodecSample* sample)
{
    int ret = ERROR_SUCCESS;
    
    int PictureLength = stream->size() - stream->pos();
    
    // 5.3.4.2.1 Syntax, H.264-AVC-ISO_IEC_14496-15.pdf, page 16
    // 5.2.4.1 AVC decoder configuration record
    // 5.2.4.1.2 Semantics
    // The value of this field shall be one of 0, 1, or 3 corresponding to a
    // length encoded with 1, 2, or 4 bytes, respectively.
    srs_assert(NAL_unit_length != 2);
    
    // 5.3.4.2.1 Syntax, H.264-AVC-ISO_IEC_14496-15.pdf, page 20
    for (int i = 0; i < PictureLength;) {
        // unsigned int((NAL_unit_length+1)*8) NALUnitLength;
        if (!stream->require(NAL_unit_length + 1)) {
            ret = ERROR_HLS_DECODE_ERROR;
            srs_error("avc decode NALU size failed. ret=%d", ret);
            return ret;
        }
        int32_t NALUnitLength = 0;
        if (NAL_unit_length == 3) {
            NALUnitLength = stream->read_4bytes();
        } else if (NAL_unit_length == 1) {
            NALUnitLength = stream->read_2bytes();
        } else {
            NALUnitLength = stream->read_1bytes();
        }
        
        // maybe stream is invalid format.
        // see: https://github.com/winlinvip/simple-rtmp-server/issues/183
        if (NALUnitLength < 0) {
            ret = ERROR_HLS_DECODE_ERROR;
            srs_error("maybe stream is AnnexB format. ret=%d", ret);
            return ret;
        }
        
        // NALUnit
        if (!stream->require(NALUnitLength)) {
            ret = ERROR_HLS_DECODE_ERROR;
            srs_error("avc decode NALU data failed. ret=%d", ret);
            return ret;
        }
        // 7.3.1 NAL unit syntax, H.264-AVC-ISO_IEC_14496-10.pdf, page 44.
        if ((ret = sample->add_sample_unit(stream->data() + stream->pos(), NALUnitLength)) != ERROR_SUCCESS) {
            srs_error("avc add video sample failed. ret=%d", ret);
            return ret;
        }
        stream->skip(NALUnitLength);
        
        i += NAL_unit_length + 1 + NALUnitLength;
    }
    
    return ret;
}