Newest 'libx264' Questions - Stack Overflow

http://stackoverflow.com/questions/tagged/libx264

Les articles publiés sur le site

  • Confused about x264 and encoding video frames

    26 février 2015, par spartygw

    I built a test driver for encoding a series of images I have captured. I am using libx264 and based my driver off of this guy's answer:

    StackOverflow link

    In my case I am starting out by reading in a JPG image and converting to YUV and passing that same frame over and over in a loop to the x264 encoder.

    My expectation was that since the frame is the same that the output from the encoder would be very small and constant.

    Instead I find that the NAL payload is varied from a few bytes to a few KB and also varies highly depending on the frame rate I specify in the encoder parameters.

    Obviously I don't understand video encoding. Why does the output size vary so much?

    int main() 
{
  Image image(WIDTH, HEIGHT);
  image.FromJpeg("frame-1.jpg");

  unsigned char *data = image.GetRGB();

  x264_param_t param;

  x264_param_default_preset(&param, "fast", "zerolatency");
  param.i_threads = 1;
  param.i_width = WIDTH;
  param.i_height = HEIGHT;
  param.i_fps_num = FPS;
  param.i_fps_den = 1;

  // Intra refres:
  param.i_keyint_max = FPS;
  param.b_intra_refresh = 1;

  //Rate control:
  param.rc.i_rc_method = X264_RC_CRF;
  param.rc.f_rf_constant = FPS-5;
  param.rc.f_rf_constant_max = FPS+5;

  //For streaming:
  param.b_repeat_headers = 1;
  param.b_annexb = 1;

  x264_param_apply_profile(&param, "baseline");

  // initialize the encoder
  x264_t* encoder = x264_encoder_open(&param);
  x264_picture_t pic_in, pic_out;
  x264_picture_alloc(&pic_in, X264_CSP_I420, WIDTH, HEIGHT);
  // X264 expects YUV420P data use libswscale 
  // (from ffmpeg) to convert images to the right format
  struct SwsContext* convertCtx =
        sws_getContext(WIDTH, HEIGHT, PIX_FMT_RGB24, WIDTH, HEIGHT,
                       PIX_FMT_YUV420P, SWS_FAST_BILINEAR,
                       NULL, NULL, NULL);

  // encoding is as simple as this then, for each frame do:
  // data is a pointer to your RGB structure
  int srcstride = WIDTH*3; //RGB stride is just 3*width
  sws_scale(convertCtx, &data, &srcstride, 0, HEIGHT,
            pic_in.img.plane, pic_in.img.i_stride);
  x264_nal_t* nals;
  int i_nals;
  int frame_size =
        x264_encoder_encode(encoder, &nals, &i_nals, &pic_in, &pic_out);

  int max_loop=15;
  int this_loop=1;

  while (frame_size >= 0 && --max_loop)
  {
      cout << "------------" << this_loop++ << "-----------------\n";
      cout << "Frame size = " << frame_size << endl;
      cout << "output has " << pic_out.img.i_csp << " colorspace\n";
      cout << "output has " << pic_out.img.i_plane << " # img planes\n";

      cout << "i_nals = " << i_nals << endl;
      for (int n=0; n

  • Can't write .mp4 files - Could not open codec 'libx264' : Unspecified error

    17 février 2015, par margaridagomes

    Days ago I installed the latest 2.4 branch withou ffmpeg. I'm using Ubuntu 14.04 and I don't have at all ffmpeg in my Virtual Machine.

    I want to write .mp4 video files and the input files are also .mp4. The input codec is avc1.

    I can't obtain any results, the errors can be seen below.

    Error

    [libx264 @ 0x9357bc0] broken ffmpeg default settings detected
[libx264 @ 0x9357bc0] use an encoding preset (e.g. -vpre medium)
[libx264 @ 0x9357bc0] preset usage: -vpre  -vpre 
[libx264 @ 0x9357bc0] speed presets are listed in x264 --help
[libx264 @ 0x9357bc0] profile is optional; x264 defaults to high
Could not open codec 'libx264': Unspecified error
Could not open the output video for write: /home/margarida/exams_2014/Output.mp4

    Simplified Code

    int main(int argc, char *argv[]) {
            VideoWriter outputVideo;

            // Get Codec Type
            int ex = static_cast(cap.get(CV_CAP_PROP_FOURCC));

            // Transform from int to char via Bitwise operators
            char EXT[] = { (char) (ex & 0XFF), (char) ((ex & 0XFF00) >> 8),
                            (char) ((ex & 0XFF0000) >> 16), (char) ((ex & 0XFF000000)
                                    >> 24), 0 };

            // Acquire input size
            Size S = Size((int) cap.get(CV_CAP_PROP_FRAME_WIDTH),
                            (int) cap.get(CV_CAP_PROP_FRAME_HEIGHT));

            cout << "Input codec type: " << EXT << endl;

            // Open the output
            outputVideo.open(newname, ex, cap.get(CV_CAP_PROP_FPS), S, true);

            if (!outputVideo.isOpened()) {
                cout << "Could not open the output video for write " << endl;
                        return -1;
                    }

                    while (true) {
                        cap >> frame;
                        if (frame.empty()) {
                            cerr << "nao apanhou frame" << endl;
                            break;
                        }

                        cinzento = acinzentar(frame);
                        imshow("Cinzento", cinzento);

                        outputVideo.write(cinzento);

                        switch(waitKey(10)){

                        case 27:
                            //'esc' has been pressed (ASCII value for 'esc' is 27)
                            //exit program.
                            return 0;

                        }
                    }
                   return 0;
                }

    My cmake was this:

    cmake -D WITH_TBB=ON -D CMAKE_INSTALL_PREFIX=/usr/local -D BUILD_NEW_PYTHON_SUPPORT=ON -D WITH_V4L=ON -D INSTALL_C_EXAMPLES=ON -D INSTALL_PYTHON_EXAMPLES=ON -D BUILD_EXAMPLES=ON -D WITH_QT=ON -D WITH_OPENGL=ON -D WITH_VTK=ON -D WITH_FFMPEG=OFF -D WITH_IPP=OFF ..

    Can anyone help solving my problem?

    Thanks in advance.

  • Using WebHDFS to play video over HTTP

    3 février 2015, par Qin.Yang

    I used ffmpeg + libx264 to convert file format as H264, then uploaded the file to Hadoop. I used WebHDFS to access the file by HTTP, but can not online play. If I download this file over HTTP, it can play by HTML5 video. My English is poor, hope you know what I mean.

  • how to output a H264 encoded video with ffmpeg in php exec() command

    28 janvier 2015, par Harish Kumar

    I have the following php command to generate a water marked video with a input video, which is working fine. but its not playing in the browser anymore. To do so i research a lot over web and i found that i need to upgrade the libx264 library on my ffmpeg extension on the server which i already did. now what modification do i do to make my command work to generate H264 encode video.

    here is the command i am using

    /usr/local/bin/ffmpeg -i baby.mp4 -i sos.png -filter_complex \"overlay=(main_w-overlay_w)/2:(main_h-overlay_h)/2\" -codec:a copy watermarked-video.mp4

  • x264 : Using NAL size limitation ruins the stream

    21 janvier 2015, par Dan Tumaykin

    I'm using x264 to compress a video stream from a webcam with this settings:

    x264_param_default_preset(&param, "veryfast", "zerolatency");

param.i_threads = 1;
param.i_fps_den = 1;
param.b_annexb = 1;

param.i_keyint_max = 30;
param.rc.i_rc_method = X264_RC_CRF;
param.rc.f_rf_constant = 25;
param.rc.f_rf_constant_max = 35;

param.b_repeat_headers = 1;
x264_param_apply_profile(&param, "baseline");

param.i_slice_max_size = X264_NAL_MAX_SIZE;

    I would like to fit NAL into MTU size, but if I set a small max size, the stream is ruined - it blinks randomly between black and white, with some clues of original image in background. The bigger is the max_size, less probable is for the stream to be ruined. So my question is - can we have small NALUs and a correct video stream?

    UPD: I use FFmpeg as a decoder.

Navigation

Sites Web