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• Django api returns Gif as JPG despite a function to add it as video

  7 septembre 2023, par Earthling

  I'm trying to upload a .gif to my django 3.2 api. I have already ran troubleshoots through Postman and came to the conclusion that my flutter app sends it as a .gif and it gets returned as a .jpg. The problem is on the backend. Here is my relevant code which checks for file_meme subtype and then the function should convert the incoming .gif to a video :

  


  


  


  def add_media(self, file, order=None):
    check_can_add_media(post=self)

    is_in_memory_file = isinstance(file, InMemoryUploadedFile) or isinstance(file, SimpleUploadedFile)

    if is_in_memory_file:
        file_mime = magic.from_buffer(file.read())
    elif isinstance(file, TemporaryUploadedFile):
        file_mime = magic.from_file(file.temporary_file_path())
    else:
        file_mime = magic.from_file(file.name)

    check_mimetype_is_supported_media_mimetypes(file_mime)
    # Mime check moved pointer
    file.seek(0)

    file_mime_types = file_mime.split('/')

    file_mime_type = file_mime_types[0]
    file_mime_subtype = file_mime_types[1]

    temp_files_to_close = []

    if file_mime_subtype == 'gif':
                if is_in_memory_file:
                    file = write_in_memory_file_to_disk(file)

                temp_dir = tempfile.gettempdir()
                converted_gif_file_name = os.path.join(temp_dir, str(uuid.uuid4()) + '.mp4')

                ff = ffmpy.FFmpeg(
                    inputs={file.temporary_file_path() if hasattr(file, 'temporary_file_path') else file.name: None},
                    outputs={converted_gif_file_name: None})
                ff.run()
                converted_gif_file = open(converted_gif_file_name, 'rb')
                temp_files_to_close.append(converted_gif_file)
                file = File(file=converted_gif_file)
                file_mime_type = 'video'

            has_other_media = self.media.exists()
    
    if file_mime_type == 'image':
        post_image = self._add_media_image(image=file, order=order)
        if not has_other_media:
            self.media_width = post_image.width
            self.media_height = post_image.height
            self.media_thumbnail = file

    elif file_mime_type == 'video':
        post_video = self._add_media_video(video=file, order=order)
        if not has_other_media:
            self.media_width = post_video.width
            self.media_height = post_video.height
            self.media_thumbnail = post_video.thumbnail.file
    else:
        raise ValidationError(
            _('Unsupported media file type')
        )

    for file_to_close in temp_files_to_close:
        file_to_close.close()
            
            
    self.save()        

  


  


  



  def _add_media_image(self, image, order):
    return PostImage.create_post_media_image(image=image, post_id=self.pk, order=order)

def _add_media_video(self, video, order):
    return PostVideo.create_post_media_video(file=video, post_id=self.pk, order=order)


@classmethod
    def create_post_media_image(cls, image, post_id, order):
        hash = sha256sum(file=image.file)
        post_image = cls.objects.create(image=image, post_id=post_id, hash=hash, thumbnail=image)
        PostMedia.create_post_media(type=PostMedia.MEDIA_TYPE_IMAGE,
                                    content_object=post_image,
                                    post_id=post_id, order=order)
        return post_image


@classmethod
    def create_post_media_video(cls, file, post_id, order):
        hash = sha256sum(file=file.file)
        video_backend = get_backend()

        if isinstance(file, InMemoryUploadedFile):
            # If its in memory, doing read shouldn't be an issue as the file should be small.
            in_disk_file = write_in_memory_file_to_disk(file)
            thumbnail_path = video_backend.get_thumbnail(video_path=in_disk_file.name, at_time=0.0)
        else:
            thumbnail_path = video_backend.get_thumbnail(video_path=file.file.name, at_time=0.0)

        with open(thumbnail_path, 'rb+') as thumbnail_file:
            post_video = cls.objects.create(file=file, post_id=post_id, hash=hash, thumbnail=File(thumbnail_file), )
        PostMedia.create_post_media(type=PostMedia.MEDIA_TYPE_VIDEO,
                                    content_object=post_video,
                                    post_id=post_id, order=order)
        return post_video
        
    


  


  I'm not sure where the problem is. From my limited understanding, it is taking only the first frame of the .gif and uploading it as an image.

  


• Python & OpenCV - VideoCapture.read() always returns false

  21 août 2017, par Julen

  I need to extract frames from a video at a given time, and I’m using OpenCV for it. I’m using Linux Mint 18.1, but it must also run on Ubuntu.

  This code example is not working for me :

  import cv2
  
  
  
  print('making screenshot from {0}'.format('/tmp/big_buck_bunny_720p_5mb.mp4'))
  
  
  
  cap = cv2.VideoCapture(video_path)
  
  cap.set(cv2.CAP_PROP_POS_MSEC,1000)
  
  ret,frame = cap.read()
  
  print(ret)                      # This is false
  
  cv2.imwrite("image.jpg", frame) # Creates an empty file

  (I’ve checked that the path of the video is correct and that the file is not corrupted).

  I have installed the Python OpenCV 3.3.0 version :

  >>> import cv2
  
  >>> cv2.__version__
  
  '3.3.0'

  I’ve compiled and installed the source for OpenCV (with the WITH_FFMPEG=ON option) :

  git clone https://github.com/Itseez/opencv.git /tmp/opencv-3                                                                                                                                                                                
  
  /tmp/opencv-3                                                                                                                                                                                                                            
  
  mkdir -p release                                                                                                                                                                                                                            
  
  cd release                                                                                                                                                                                                                                  
  
  cmake -D WITH_FFMPEG=ON -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/usr/local ..                                                                                                                                                   
  
  make                                                                                                                                                                                                                                        
  
  sudo make install     

  The output of ffmpeg -version is the following :

  ffmpeg version 2.8.11-0ubuntu0.16.04.1 Copyright (c) 2000-2017 the FFmpeg developers
  
  built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.4) 20160609
  
  configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
  
  libavutil      54. 31.100 / 54. 31.100
  
  libavcodec     56. 60.100 / 56. 60.100
  
  libavformat    56. 40.101 / 56. 40.101
  
  libavdevice    56.  4.100 / 56.  4.100
  
  libavfilter     5. 40.101 /  5. 40.101
  
  libavresample   2.  1.  0 /  2.  1.  0
  
  libswscale      3.  1.101 /  3.  1.101
  
  libswresample   1.  2.101 /  1.  2.101
  
  libpostproc    53.  3.100 / 53.  3.100

  What am I missing ?

• avcodec_find_encoder_by_name() returns NULL

  27 décembre 2019, par GiuTor

  I’m trying to compile the following example I found on ffmpeg documentation :

   /*
  
   * Copyright (c) 2001 Fabrice Bellard
  
   *
  
   * 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.
  
   */
  
  
  
   // compile with gcc -o encode_video encode_video.c -lavutil -lavcodec -lz -lm
  
  
  
  /**
  
   * @file
  
   * video encoding with libavcodec API example
  
   *
  
   * @example encode_video.c
  
   */
  
  
  
  #include 
  
  #include 
  
  #include 
  
  
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  
  
  #include <libavutil></libavutil>opt.h>
  
  #include <libavutil></libavutil>imgutils.h>
  
  
  
  static void encode(AVCodecContext *enc_ctx, AVFrame *frame, AVPacket *pkt,
  
                     FILE *outfile)
  
  {
  
      int ret;
  
  
  
      /* send the frame to the encoder */
  
      if (frame)
  
          printf("Send frame %3"PRId64"\n", frame->pts);
  
  
  
      ret = avcodec_send_frame(enc_ctx, frame);
  
      if (ret &lt; 0) {
  
          fprintf(stderr, "Error sending a frame for encoding\n");
  
          exit(1);
  
      }
  
  
  
      while (ret >= 0) {
  
          ret = avcodec_receive_packet(enc_ctx, pkt);
  
          if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
  
              return;
  
          else if (ret &lt; 0) {
  
              fprintf(stderr, "Error during encoding\n");
  
              exit(1);
  
          }
  
  
  
          printf("Write packet %3"PRId64" (size=%5d)\n", pkt->pts, pkt->size);
  
          fwrite(pkt->data, 1, pkt->size, outfile);
  
          av_packet_unref(pkt);
  
      }
  
  }
  
  
  
  int main(int argc, char **argv)
  
  {
  
      const char *filename, *codec_name;
  
      const AVCodec *codec;
  
      AVCodecContext *c= NULL;
  
      int i, ret, x, y;
  
      FILE *f;
  
      AVFrame *frame;
  
      AVPacket *pkt;
  
      uint8_t endcode[] = { 0, 0, 1, 0xb7 };
  
  
  
      if (argc &lt;= 2) {
  
          fprintf(stderr, "Usage: %s <output file="file"> <codec>\n", argv[0]);
  
          exit(0);
  
      }
  
      filename = argv[1];
  
      codec_name = argv[2];
  
  
  
      /* find the mpeg1video encoder */
  
      codec = avcodec_find_encoder_by_name(codec_name);
  
      if (!codec) {
  
          fprintf(stderr, "Codec '%s' not found\n", codec_name);
  
          exit(1);
  
      }
  
  
  
      c = avcodec_alloc_context3(codec);
  
      if (!c) {
  
          fprintf(stderr, "Could not allocate video codec context\n");
  
          exit(1);
  
      }
  
  
  
      pkt = av_packet_alloc();
  
      if (!pkt)
  
          exit(1);
  
  
  
      /* put sample parameters */
  
      c->bit_rate = 400000;
  
      /* resolution must be a multiple of two */
  
      c->width = 352;
  
      c->height = 288;
  
      /* frames per second */
  
      c->time_base = (AVRational){1, 25};
  
      c->framerate = (AVRational){25, 1};
  
  
  
      /* emit one intra frame every ten frames
  
       * check frame pict_type before passing frame
  
       * to encoder, if frame->pict_type is AV_PICTURE_TYPE_I
  
       * then gop_size is ignored and the output of encoder
  
       * will always be I frame irrespective to gop_size
  
       */
  
      c->gop_size = 10;
  
      c->max_b_frames = 1;
  
      c->pix_fmt = AV_PIX_FMT_YUV420P;
  
  
  
      if (codec->id == AV_CODEC_ID_H264)
  
          av_opt_set(c->priv_data, "preset", "slow", 0);
  
  
  
      /* open it */
  
      ret = avcodec_open2(c, codec, NULL);
  
      if (ret &lt; 0) {
  
          fprintf(stderr, "Could not open codec: %s\n", av_err2str(ret));
  
          exit(1);
  
      }
  
  
  
      f = fopen(filename, "wb");
  
      if (!f) {
  
          fprintf(stderr, "Could not open %s\n", filename);
  
          exit(1);
  
      }
  
  
  
      frame = av_frame_alloc();
  
      if (!frame) {
  
          fprintf(stderr, "Could not allocate video frame\n");
  
          exit(1);
  
      }
  
      frame->format = c->pix_fmt;
  
      frame->width  = c->width;
  
      frame->height = c->height;
  
  
  
      ret = av_frame_get_buffer(frame, 32);
  
      if (ret &lt; 0) {
  
          fprintf(stderr, "Could not allocate the video frame data\n");
  
          exit(1);
  
      }
  
  
  
      /* encode 1 second of video */
  
      for (i = 0; i &lt; 25; i++) {
  
          fflush(stdout);
  
  
  
          /* make sure the frame data is writable */
  
          ret = av_frame_make_writable(frame);
  
          if (ret &lt; 0)
  
              exit(1);
  
  
  
          /* prepare a dummy image */
  
          /* Y */
  
          for (y = 0; y &lt; c->height; y++) {
  
              for (x = 0; x &lt; c->width; x++) {
  
                  frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3;
  
              }
  
          }
  
  
  
          /* Cb and Cr */
  
          for (y = 0; y &lt; c->height/2; y++) {
  
              for (x = 0; x &lt; c->width/2; x++) {
  
                  frame->data[1][y * frame->linesize[1] + x] = 128 + y + i * 2;
  
                  frame->data[2][y * frame->linesize[2] + x] = 64 + x + i * 5;
  
              }
  
          }
  
  
  
          frame->pts = i;
  
  
  
          /* encode the image */
  
          encode(c, frame, pkt, f);
  
      }
  
  
  
      /* flush the encoder */
  
      encode(c, NULL, pkt, f);
  
  
  
      /* add sequence end code to have a real MPEG file */
  
      if (codec->id == AV_CODEC_ID_MPEG1VIDEO || codec->id == AV_CODEC_ID_MPEG2VIDEO)
  
          fwrite(endcode, 1, sizeof(endcode), f);
  
      fclose(f);
  
  
  
      avcodec_free_context(&amp;c);
  
      av_frame_free(&amp;frame);
  
      av_packet_free(&amp;pkt);
  
  
  
      return 0;
  
  }
  
  </codec></output>

  ffmpeg -codecs return a bunch of codecs among which libx264 and libx265. When I run the above code I get NULL from avcodec_find_encoder_by_name() :

  gt@gt-Aspire-E1-570 : /libav$ ./encode_video pippo libx264
  Codec ’libx264’ not found
  gt@gt-Aspire-E1-570 : /libav$ ./encode_video pippo x264
  Codec ’x264’ not found
  gt@gt-Aspire-E1-570 : /libav$ ./encode_video pippo H264
  Codec ’H264’ not found
  gt@gt-Aspire-E1-570 : /libav$

  Can someone help please ?

  Thanks