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• FFMpeg kmsgrab record pixels wrong

  21 avril 2020, par Alex Joel

  ffmpeg -f kmsgrab -i - -framerate 60 -vf 'hwdownload,format=bgr0' -preset ultrafast out.mkv

  



  This is how a video frame should look like

This is how it is recorded by ffmpeg
https://drive.google.com/file/d/11jOUTk3ZxOfwnfd7zS4d4qBLApTS3Vmx/view?usp=sharing

  


• The GStreamer custom plugin's _transform_frame_ip function is not working [closed]

  28 octobre 2024, par Amiya

  I have created a custom GStreamer plugin named brightness I checked it with the gst-inspect-1.0 and gst-launch-1.0 commands and am able to get video output. I used the following command :

  


  gst-launch-1.0 filesrc location=sample-15s.mp4 ! decodebin ! videoconvert ! video/x-raw,format=RGB ! brightness brightness=1.0 ! videoconvert ! vp8enc ! webmmux ! filesink location=capture1.webm


  


  Codebaselink : link

  


  In the codebase, I am setting all data to 0, so I expect a black video in the output file, capture1.webm. However, I'm getting the same video as the input. I also added a print statement after setting the data to 0, and it printed 0 as expected. I'm not sure why the output is not as expected.

  


  _transform_frame_ip function details :

  


  static GstFlowReturn gst_brightness_transform_frame_ip(GstVideoFilter *filter, GstVideoFrame *frame) {
    GstBrightness *brightness = GST_BRIGHTNESS(filter);
    guint8 *data = GST_VIDEO_FRAME_PLANE_DATA(frame, 0);
    gsize size = GST_VIDEO_FRAME_COMP_PSTRIDE(frame, 0) * GST_VIDEO_FRAME_HEIGHT(frame);

    printf("frame received:%f\n", brightness->brightness);
    for (gsize i = 0; i < size; i++) {
        gint pixel = data[i] + (gint)(brightness->brightness * 255.0);
        data[i] = 0; //CLAMP(pixel, 0, 255);
    }

    return GST_FLOW_OK;
}


  


  I am expecting black video in the output file.

  


• Add support for playing Audible AAXC (.aaxc) files [PATCH v4]

  1er janvier 2000, par Vesselin Bontchev

  Add support for playing Audible AAXC (.aaxc) files [PATCH v4]
  The AAXC container format is the same as the (already supported) Audible
  
  AAX format but it uses a different encryption scheme.
  Note : audible_key and audible_iv values are variable (per file) and are
  
  externally fed.
  It is possible to extend https://github.com/mkb79/Audible to derive the
  
  audible_key and audible_key values.
  Relevant code :
  def decrypt_voucher(deviceSerialNumber, customerId, deviceType, asin, voucher) :
  
      buf = (deviceType + deviceSerialNumber + customerId + asin).encode("ascii")
  
      digest = hashlib.sha256(buf).digest()
  
      key = digest[0:16]
  
      iv = digest[16 :]
      # decrypt "voucher" using AES in CBC mode with no padding
  
      cipher = AES.new(key, AES.MODE_CBC, iv)
  
      plaintext = cipher.decrypt(voucher).rstrip(b"\x00")  # improve this !
  
      return json.loads(plaintext)
  The decrypted "voucher" has the required audible_key and audible_iv
  
  values.
  Update (Nov-2020) : This patch has now been tested by multiple folks -
  
  details at the following URL :
  https://github.com/mkb79/Audible/issues/3
  Signed-off-by : Vesselin Bontchev <vesselin.bontchev@yandex.com>
  

  • [DH] libavformat/isom.h
  • [DH] libavformat/mov.c