The VideoLAN Forums

Posted: **08 Sep 2020 16:11**

Hi all,

With the following code, I get the same data over UDP however DecodeFrameNoDelay returns an error about "Sequence Parameter Sets"

I'm new to codecs and video streaming so maybe there is something I'm missing in libvlc config or openh264 usage ?

Broadcasting part :

Code: Select all

// broadcaster.h
class Broadcaster
{
    ...

    std::vector<uint8_t> audioBuffer_;
    std::vector<uint8_t> videoBuffer_;
};

// broadcaster.cpp
void cbVideoPrerender(void* p_video_data, uint8_t** pp_pixel_buffer, int size)
{
    Broadcaster::instance()->videoPrerender(p_video_data, pp_pixel_buffer, size);
}

void cbVideoPostrender(
    void* p_video_data, uint8_t* p_pixel_buffer, int width, int height, int pixel_pitch, int size, int64_t pts)
{
    Broadcaster::instance()->videoPostrender(p_video_data, p_pixel_buffer, width, height, pixel_pitch, size, pts);
}

void Broadcaster::videoPrerender(void* p_video_data, uint8_t** pp_pixel_buffer, int size)
{
    spdlog::debug("videoPrerender");
    videoBuffer_.resize(size);
    *pp_pixel_buffer = videoBuffer_.data();
}

void Broadcaster::videoPostrender(
    void* p_video_data, uint8_t* p_pixel_buffer, int width, int height, int pixel_pitch, int size, int64_t pts)
{
    spdlog::debug("videoPostrender");

    std::vector<unsigned char> frame;
    frame.resize(size);
    memcpy(frame.data(), p_pixel_buffer, size);
    spdlog::debug("size: {}", size);
    // sending data over UDP
}

Broadcaster::Broadcaster()
{
    std::ostringstream stream;
    stream << "#transcode{vcodec=h264,venc=x264{profile=baseline,level=3.0},vb=800,scale=1,acodec=mp3,ab=128,channels=2,samplerate=44100}:smem{";
    stream << "video-prerender-callback=" << (long long int)(intptr_t)(void*)&cbVideoPrerender << ",";
    stream << "video-postrender-callback=" << (long long int)(intptr_t)(void*)&cbVideoPostrender << ",";
    stream << "audio-prerender-callback=" << (long long int)(intptr_t)(void*)&cbAudioPrerender << ",";
    stream << "audio-postrender-callback=" << (long long int)(intptr_t)(void*)&cbAudioPostrender << ",";
    stream << "audio-data=" << (long long int)0 << ",";
    stream << "video-data=" << (long long int)0 << "";
    stream << "},";

    inst_ = libvlc_new(0, NULL);

    std::vector<const char*> params = {
        "sout", "sout-all", "screen-top=0", "screen-left=0", "screen-width=1920", "screen-height=1080", "screen-fps=10"};

    libvlc_vlm_add_broadcast(inst_, "stream", "screen://", stream.str().c_str(), params.size(), params.data(), 1, 0);
}

Decoding part (based on https://github.com/cisco/openh264/wiki/ ... ForDecoder):

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// streamwindow.h
class StreamWindow
{
    ...

    ISVCDecoder*   pSvcDecoder_;
    unsigned char* pData_[3];
    SDecodingParam sDecParam_ = {0};
};

// streamwindow.cpp
static spdlog::level::level_enum openh264_to_spdlog(int level)
{
    switch (level)
    {
    case WELS_LOG_QUIET:
        return spdlog::level::level_enum::trace;
    case WELS_LOG_ERROR:
        return spdlog::level::level_enum::err;
    case WELS_LOG_WARNING:
        return spdlog::level::level_enum::warn;
    case WELS_LOG_INFO:
        return spdlog::level::level_enum::info;
    case WELS_LOG_DEBUG:
        return spdlog::level::level_enum::debug;
    case WELS_LOG_DETAIL:
        return spdlog::level::level_enum::info;
    default:
        return spdlog::level::level_enum::debug;
    }
}

static void openh264_spdlog(void* context, int level, const char* message)
{
    spdlog::log(openh264_to_spdlog(level), message);
}

StreamWindow::StreamWindow()
{
    WelsCreateDecoder(&pSvcDecoder_);
    sDecParam_.sVideoProperty.eVideoBsType = VIDEO_BITSTREAM_SVC;
    pSvcDecoder_->Initialize(&sDecParam_);

    int               log_level = WELS_LOG_DETAIL;
    WelsTraceCallback callback_function;
    callback_function = openh264_spdlog;
    pSvcDecoder_->SetOption(DECODER_OPTION_TRACE_LEVEL, &log_level);
    pSvcDecoder_->SetOption(DECODER_OPTION_TRACE_CALLBACK, (void*)&callback_function);

    ...
}

// called on received udp data
void StreamWindow::decodeStreamData(unsigned char* data, int size)
{
    SBufferInfo sDstBufInfo;
    memset(&sDstBufInfo, 0, sizeof(SBufferInfo));
    DECODING_STATE iRet = pSvcDecoder_->DecodeFrameNoDelay(data, size, pData_, &sDstBufInfo);
    if (iRet != 0)
    {
        spdlog::warn("DecodeFrameNoDelay failed: 0x{0:x}", iRet);
    }

    ...
}

libVLC logs

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[00007f2f440011f0] x264 encoder: using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
[00007f2f440011f0] x264 encoder: profile Constrained Baseline, level 3.0, 4:2:0, 8-bit
[00007f2f440011f0] x264 encoder: final ratefactor: 38.99
[00007f2f440011f0] x264 encoder: using SAR=1/1
[00007f2f440011f0] x264 encoder: using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
[00007f2f440011f0] x264 encoder: profile Constrained Baseline, level 3.0, 4:2:0, 8-bit

decodeStreamData logs

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[2020-09-07 21:52:38.463] [debug] decodeStreamData, size: 47022
[2020-09-07 21:52:38.464] [warning] [OpenH264] this = 0x0x5630b8e202b0, Warning:parse_nal(), no exist Sequence Parameter Sets ahead of sequence when try to decode NAL(type:5).
[2020-09-07 21:52:38.464] [info] [OpenH264] this = 0x0x5630b8e202b0, Info:decode failed, failure type:16 
[2020-09-07 21:52:38.464] [warning] DecodeFrameNoDelay failed: 0x10

Full project: https://github.com/xavi-b/stream

The VideoLAN Forums

Issue decoding with openh264 a libvlc broadcast sent over UDP

Issue decoding with openh264 a libvlc broadcast sent over UDP