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  • ffmpeg Bmp to yuv : Crash at sws_scale

    28 décembre 2015, par the-owner

    The context :
    I have a succession of continuous bitmap and I want to encode them into a light video format.
    I use ffmpeg version 2.8.3 (the build here), under qt5, qt IDE, and msvc2013 for win32.

    The problem :
    My code crash at sws_scale () (and sometimes at avcodec_encode_video2()). When I explore the stack, the crash event occurs at sws_getCachedContext (). (I can only see the stack with these ffmpeg builds).
    I only use these ffmpeg libraries (from the Qt .pro file) :

    LIBS += -lavcodec -lavformat -lswscale -lavutil

    It’s swscale which bug. And this is the code :

    void newVideo ()
    
{
    
    ULONG_PTR gdiplusToken;
    
    GdiplusStartupInput gdiplusStartupInput;
    
    GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);
    

    
    initBitmap (); //init bmp
    
    int screenWidth =  bmp.bmiHeader.biWidth;
    
    int screenHeight = bmp.bmiHeader.biHeight;
    

    
    AVCodec * codec;
    
    AVCodecContext * c = NULL;
    
    uint8_t * outbuf;
    
    int i, out_size, outbuf_size;
    

    

    
    avcodec_register_all();
    

    
    qDebug () << "Video encoding\n";
    

    
    // Find the mpeg1 video encoder
    
    codec = avcodec_find_encoder(AV_CODEC_ID_H264);
    
    if (!codec)
    
    {
    
        qDebug () << "Codec not found\n";
    
        avcodec_close(c);
    
        av_free(c);
    
        return;
    
    }
    
    else
    
        qDebug () << "H264 codec found\n";
    

    
    c = avcodec_alloc_context3(codec);
    

    
    c->bit_rate = 1000000;
    
    c->width = 800; // resolution must be a multiple of two (1280x720),(1900x1080),(720x480)
    
    c->height = 600;
    
    c->time_base.num = 1; // framerate numerator
    
    c->time_base.den = 25; // framerate denominator
    
    c->gop_size = 30; // emit one intra frame every ten frames
    
    c->max_b_frames = 1; // maximum number of b-frames between non b-frames
    
    c->pix_fmt = AV_PIX_FMT_YUV420P; //Converstion RGB to YUV ?
    
    c->codec_id = AV_CODEC_ID_H264;
    

    
    struct SwsContext* fooContext = sws_getContext(screenWidth, screenHeight,
    
                                                   AV_PIX_FMT_RGB32,
    
                                                   c->width, c->height,
    
                                                   AV_PIX_FMT_YUV420P,
    
                                                   SWS_FAST_BILINEAR,
    
                                                   NULL, NULL, NULL);
    

    
    // Open the encoder
    
    if (avcodec_open2(c, codec, NULL) < 0)
    
    {
    
        qDebug () << "Could not open codec\n";
    
        avcodec_close(c);
    
        av_free(c);
    
        return;
    
    }
    
    else qDebug () << "H264 codec opened\n";
    

    
    outbuf_size = 100000 + c->width*c->height*(32>>3);//*(32>>3); // alloc image and output buffer
    
    outbuf = static_cast(malloc(outbuf_size));
    
    qDebug() << "Setting buffer size to: " << outbuf_size << "\n";
    

    
    FILE* f = fopen("TEST.mpg","wb");
    
    if(!f) qDebug() << "x - Cannot open video file for writing\n";
    
    else qDebug() << "Opened video file for writing\n";
    

    
    // encode 5 seconds of video
    
    for (i = 0; i < STREAM_FRAME_RATE*STREAM_DURATION; i++) //the stop condition i < 5.0*5
    
    {
    
        qDebug () << "i = " << i;
    
        fflush(stdout);
    

    
        HBITMAP hBmp;
    
        if (GetScreen(hBmp) == -1) return;
    
        BYTE * pPixels;// = new BYTE [bmp.bmiHeader.biSizeImage];
    
        pPixels = getPixels (hBmp);
    
        DeleteObject (hBmp);
    

    
        int nbytes = avpicture_get_size(AV_PIX_FMT_YUV420P, c->width, c->height);
    
        uint8_t* outbuffer = (uint8_t*)av_malloc(nbytes*sizeof(uint8_t));
    
        if(!outbuffer) // check if(outbuf) instead
    
        {
    
            qDebug () << "Bytes cannot be allocated";
    
            return;
    
        }
    

    
        AVFrame* inpic = avcodec_alloc_frame(); //av_frame_alloc () ?
    
        AVFrame* outpic = avcodec_alloc_frame();
    

    
        outpic->pts = (int64_t)((float)i * (1000.0/((float)(c->time_base.den))) * 90);
    
        if (avpicture_fill((AVPicture*) inpic, (uint8_t*) pPixels, AV_PIX_FMT_RGB32,
    
                       screenWidth, screenHeight) < 0)
    
            qDebug () <<  "avpicture_fill Fill picture with image failed"; //Fill picture with image
    

    
        if(avpicture_fill((AVPicture*) outpic, outbuffer, AV_PIX_FMT_YUV420P,
    
                       c->width, c->height) < 0)
    
            qDebug () <<  "avpicture_fill failed";
    

    
        if (av_image_alloc(outpic->data, outpic->linesize, c->width, c->height,
    
                       c->pix_fmt, 1) < 0)
    
            qDebug () <<  "av_image_alloc failed";
    

    
        inpic->data[0] += inpic->linesize[0]*(screenHeight - 1); // Flipping frame
    
        inpic->linesize[0] = -inpic->linesize[0]; // Flipping frame
    

    
////////////////////////////HERE THE BUG////////////////////////////////
    
        sws_scale(fooContext,
    
                  inpic->data, inpic->linesize,
    
                  0, c->height,
    
                  outpic->data, outpic->linesize); //HERE THE BUG
    

    
        av_free_packet((AVPacket *)outbuf);
    
        // encode the image
    
        out_size = avcodec_encode_video2 (c, (AVPacket *) outbuf,
    
                                          (AVFrame *) outbuf_size, (int *) outpic);
    
///////////////////////THE CODE DONT GO BEYOND/////////////////////////////////
    

    
        qDebug () << "Encoding frame" << i <<" (size=" << out_size <<"\n";
    
        fwrite(outbuf, 1, out_size, f);
    
        delete [] pPixels;
    
        av_free(outbuffer);
    
        av_free(inpic);
    
        av_freep(outpic);
    
    }
    

    
    // get the delayed frames
    
    for(; out_size; i++)
    
    {
    
        fflush(stdout);
    
        out_size = avcodec_encode_video2 (c, (AVPacket *) outbuf,
    
                                          (AVFrame *) outbuf_size, NULL);
    
        qDebug () << "Writing frame" << i <<" (size=" << out_size <<"\n";
    
        fwrite(outbuf, 1, out_size, f);
    
    }
    

    
    // add sequence end code to have a real mpeg file
    
    outbuf[0] = 0x00;
    
    outbuf[1] = 0x00;
    
    outbuf[2] = 0x01;
    
    outbuf[3] = 0xb7;
    
    fwrite(outbuf, 1, 4, f);
    
    fclose(f);
    

    
    avcodec_close(c);
    
    free(outbuf);
    
    av_free(c);
    
    qDebug () << "Closed codec and Freed\n";
    
}

    And the output :

    Video encoding
    

    
H264 codec found
    

    
H264 codec opened
    

    
Setting buffer size to:  2020000 
    

    
Opened video file for writing
    

    
i =  0
    
**CRASH**

    I have thougth that my bitmap wasn’t good so I have crafted a bitmap just for testing, the code was :

        uint8_t* pPixels = new uint8_t[Width * 3 * Height];
    
    int x = 50;
    
    for(unsigned int i = 0; i < Width * 3 * Height; i = i + 3) // loop for generating color changing images
    
    {
    
        pPixels [i] = x % 255; //R
    
        pPixels [i + 1] = (x) % 255; //G
    
        pPixels [i + 2] = (255 - x) % 255; //B
    
    }

    However the crash continue. Perhaps, it might prove that it’s not the bitmap (pPixels) which has a problem.

    If anyone know, why I get this bug : Maybe don’t I set one parameter well ? Or one ffmpeg deprecated function ? etc.

    EDIT 1 27/12/15

    Thanks to Ronald S. Bultje The function sws_scale () does not crash with this code, however I get an error from it bad dst image pointers. My code :

    //DESTINATION FRAME            
    
if (avpicture_alloc ((AVPicture*) dst_frame, AV_PIX_FMT_YUV420P, c->width, c->height) < 0)
    
            {
    
                qDebug () <<  "# avpicture_alloc failed";
    
                return;
    
            }
    
            if(avpicture_fill((AVPicture*) dst_frame, NULL, AV_PIX_FMT_YUV420P,
    
                           c->width, c->height) < 0)
    
                qDebug () <<  "avpicture_fill failed";
    
            avcodec_align_dimensions2 (c, &c->width, &c->height, dst_frame->linesize);
    

    
//SOURCE FRAME
    
            if (avpicture_fill((AVPicture*) src_frame, (uint8_t *) pPixels, AV_PIX_FMT_RGB32,
    
                               tmp_screenWidth, tmp_screenHeight) < 0)
    
                qDebug () <<  "# avpicture_fill Fill picture with image failed"; //Fill picture with image
    
            avcodec_align_dimensions2 (c, &tmp_screenWidth, &tmp_screenHeight, src_frame->linesize);
    

    
            struct SwsContext* conversionContext = sws_getContext(tmp_screenWidth,tmp_screenHeight,AV_PIX_FMT_RGB32,c->width, c->height, AV_PIX_FMT_YUV420P,SWS_FAST_BILINEAR, NULL, NULL, NULL);
    

    
            int output_Height = sws_scale(conversionContext,
    
                                          src_frame->data, src_frame->linesize,
    
                                          0, tmp_screenHeight,
    
                                          dst_frame->data, dst_frame->linesize); //return 0 -> bad dst image pointers error

    EDIT 2 28/12/15

    I have tried to follow the Ronald S. Bultje’s suggestion and now I get a bad src image pointers error, I have investigated and worked many hours but I do not find a solution. Here, there is the new snippet :

    AVFrame* src_frame = av_frame_alloc ();
    
AVFrame* dst_frame = av_frame_alloc ();
    
AVFrame* tmp_src_frame = av_frame_alloc ();
    

    
/*........I do not use them until this snippet..........*/
    
//DESTINATION
    
//avpicture_free ((AVPicture*)dst_frame);
    
avcodec_align_dimensions2 (c, &c->width, &c->height, dst_frame->linesize);
    
if (avpicture_alloc ((AVPicture*) dst_frame, AV_PIX_FMT_YUV420P, c->width, c->height) < 0)
    
{
    
    qDebug () <<  "# avpicture_alloc failed";
    
    return;
    
}
    

    
//SOURCE
    
//stride = src_frame->linesize [0] = ((((screenWidth * bitPerPixel) + 31) & ~31) >> 3); do I need to do that ?
    
//== stride - I have gotten this formula from : https://msdn.microsoft.com/en-us/library/windows/desktop/dd318229(v=vs.85).aspx
    
if (avpicture_fill((AVPicture*) src_frame, (uint8_t *) pPixels, AV_PIX_FMT_RGB32,
    
                   screenWidth, screenHeight) < 0)
    
    qDebug () <<  "# avpicture_fill Fill picture with image failed"; //Fill picture with image
    
//linesize [0] == 21760 like commented stride
    

    
//Source TO TMP Source
    
avcodec_align_dimensions2 (c, &tmp_screenWidth, &tmp_screenHeight, tmp_src_frame->linesize);
    
if (avpicture_fill((AVPicture*) tmp_src_frame, NULL, AV_PIX_FMT_RGB32,
    
                   tmp_screenWidth, tmp_screenHeight) < 0)
    
    qDebug () <<  "# avpicture_fill Fill picture with image failed"; //Fill picture with image
    

    
av_picture_copy ((AVPicture*) tmp_src_frame, (const AVPicture*) src_frame, AV_PIX_FMT_RGB32,
    
                 screenWidth, screenHeight);
    

    
struct SwsContext* conversionContext = sws_getContext(tmp_screenWidth, tmp_screenHeight,
    
                                                      AV_PIX_FMT_RGB32,
    
                                                      c->width, c->height,
    
                                                      AV_PIX_FMT_YUV420P,
    
                                                      SWS_FAST_BILINEAR,
    
                                                      NULL, NULL, NULL);
    

    
int output_Height = sws_scale(conversionContext,
    
                              tmp_src_frame->data, tmp_src_frame->linesize,
    
                              0, tmp_screenHeight,
    
                              dst_frame->data, dst_frame->linesize);
    
//ffmpeg error = bad src image pointers
    
// output_Height == 0

    EDIT 3

    For temp Picture I have done an avcode_align_dimension2() then a avpicture_alloc() for allocating memory and avpicture_fill() in order to fill the picture pointer. Below the updated code :

    //DESTINATION
    
//avpicture_free ((AVPicture*)dst_frame);
    
avcodec_align_dimensions2 (c, &c->width, &c->height, dst_frame->linesize);
    
if (avpicture_alloc ((AVPicture*) dst_frame, AV_PIX_FMT_YUV420P, c->width, c->height) < 0)
    
{
    
    qDebug () <<  "# avpicture_alloc failed";
    
    return;
    
}
    

    
//SOURCE
    
//src_frame->linesize [0] = ((((screenWidth * bpp) + 31) & ~31) >> 3);
    
//src_frame->linesize [0] = stride;
    
if (avpicture_fill((AVPicture*) src_frame, (uint8_t *) pPixels, AV_PIX_FMT_RGB32,
    
                   screenWidth, screenHeight) < 0)
    
    qDebug () <<  "# avpicture_fill Fill picture with image failed"; //Fill picture with image
    

    
//Source TO TMP Source
    
avcodec_align_dimensions2 (c, &tmp_screenWidth, &tmp_screenHeight, tmp_src_frame->linesize);
    
if (avpicture_alloc ((AVPicture*) tmp_src_frame, AV_PIX_FMT_RGB32, tmp_screenWidth, tmp_screenHeight) < 0)
    
{
    
    qDebug () <<  "# avpicture_alloc failed";
    
    return;
    
}
    
int outbuf_size = tmp_screenWidth*tmp_screenHeight*4;// alloc image and output buffer
    
outbuf = static_cast(malloc(outbuf_size));
    
if (avpicture_fill((AVPicture*) tmp_src_frame, outbuf, AV_PIX_FMT_RGB32,
    
                   tmp_screenWidth, tmp_screenHeight) < 0)
    
    qDebug () <<  "# avpicture_fill Fill picture with image failed"; //Fill picture with image
    
av_picture_copy ((AVPicture*) tmp_src_frame, (const AVPicture*) src_frame, AV_PIX_FMT_RGB32,
    
                 tmp_screenWidth, tmp_screenHeight);
    

    
struct SwsContext* conversionContext = sws_getContext(tmp_screenWidth, tmp_screenHeight,
    
                                                      AV_PIX_FMT_RGB32,
    
                                                      c->width, c->height,
    
                                                      AV_PIX_FMT_YUV420P,
    
                                                      SWS_FAST_BILINEAR,
    
                                                      NULL, NULL, NULL);
    

    
int output_Height = sws_scale(conversionContext,
    
                              tmp_src_frame->data, tmp_src_frame->linesize,
    
                              0, tmp_screenHeight,
    
                              dst_frame->data, dst_frame->linesize);

    The call stack is as follow : av_picture_copy() is called then av_image_copy() then _VEC_memcpy() then fastcopy_I() and crash ... The problem is not the dimensions (tmp_screenWidth/Height) ? (With av_picture_copy () could we copy a picture P1 with dim W1xH1 to a picture P2 with dimension W2xH2 ?)

    EDIT 4

    Crash at av_picture_copy() which call _aligned_malloc() then av_image_copy _VEC_memcpy() and fastcopy_I()

    //SOURCE
    
if (avpicture_fill((AVPicture*) src_frame, (uint8_t *) pPixels, AV_PIX_FMT_RGB32,
    
                   screenWidth, screenHeight) < 0)
    
    qDebug () <<  "# avpicture_fill Fill picture with image failed"; //Fill picture with image
    

    
//Source TO TMP Source
    
avcodec_align_dimensions2 (c, &tmp_screenWidth, &tmp_screenHeight, tmp_src_frame->linesize);
    
if (avpicture_alloc ((AVPicture*) tmp_src_frame, AV_PIX_FMT_RGB32, tmp_screenWidth, tmp_screenHeight) < 0)
    
{
    
    qDebug () <<  "# avpicture_alloc failed";
    
    return;
    
}
    
av_picture_copy ((AVPicture*) tmp_src_frame, (const AVPicture*) src_frame, AV_PIX_FMT_RGB32,
    
                 tmp_screenWidth, tmp_screenHeight);

  • Live Photos on android implementation ?

    18 novembre 2016, par mohit gupta

    I have come up with a project which implements LIVE Photos capturing on android and I will hopefully make it open sourced,Spoiler : it takes a 1.5 second shot before and after you click the pic and combines them and make the video , While i tried it I was unable to do it with MediaRecorder in android , I even experimented with FFMPEG it just does not works . Anyone has any idea or a little light so i can follow and implement this.My min Api support is 16

  • qsv : Fix loading multiple plugins

    15 mars 2016, par Luca Barbato
    qsv : Fix loading multiple plugins

    av_get_token does not strip the trailing separator.
    • [DBH] libavcodec/qsv.c

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