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• Anomalie #4430 : image_reduire gère mal les arrondis

  4 février 2020, par jluc -

  J’ai ajouté des logs et vu que le pb est créé par image_ratio. La fonction n’est pas compliquée pourtant : https://code.spip.net/autodoc/tree/ecrire/inc/filtres_images_lib_mini.php.html#function_image_ratio

  J’ai testé sur l’image carrée en 427x427.
  À la fin j’ai ajouté un log à l’entrée qui témoigne que la fonction reçoit les arguments suivants : (427, 427, 200, 200) et un log à la fin qui montre ce qui va être renvoyé
  

  log("image_ratio renvoie ceil($destWidth)=".ceil($destWidth)
          .", ceil($destHeight)=".ceil($destHeight)
          .", max($ratioWidth, $ratioHeight)=".max($ratioWidth, $ratioHeight)) ;
  

  
  Et ça donne ça :
  

  image_ratio renvoie ceil(200)=200, ceil(200)=201, max(2.135, 2.135)=2.135
  

  Le 2eme "200" traîne un karma nano-décimal inconscient issu d’une mauvaise expérience d’arrondi à sa naissance ($destHeight = $srcHeight / $ratioWidth ; dans les lignes précédentes) et le ceil PHP en abuse violemment.

• FFmpeg api iOS "Resource temporarily unavailable"

  8 octobre 2017, par Julius Naeumann

  I’ve spent hours trying to fix this :

  I’m trying to use the ffmpeg api on iOS. My Xcode project is building and I can call ffmpeg api functions. I am trying to write code that decodes a video (Without outputting anything for now), and I keep getting error -35 : "Resource temporarily unavailable".

  The input file is from the camera roll (.mov) and I’m using Mpeg-4 for decoding. All I’m currently doing is getting data from the file, parsing it and sending the parsed packets to the decoder. When I try to get frames, all I get is an error. Does anyone know what I’m doing wrong ?

  +(void)test: (NSString*)filename outfile:(NSString*)outfilename {
  
  
  
  /* register all the codecs */
  
  avcodec_register_all();
  
  
  
  AVCodec *codec;
  
  AVCodecParserContext *parser;
  
  AVCodecContext *c= NULL;
  
  int frame_count;
  
  FILE* f;
  
  AVFrame* frame;
  
  AVPacket* avpkt;
  
  avpkt = av_packet_alloc();
  
  //av_init_packet(avpkt);
  
  char buf[1024];
  
  
  
  uint8_t inbuf[INBUF_SIZE + AV_INPUT_BUFFER_PADDING_SIZE];
  
  uint8_t *data;
  
  size_t   data_size;
  
  
  
  /* set end of buffer to 0 (this ensures that no overreading happens for damaged mpeg streams) */
  
  memset(inbuf + INBUF_SIZE, 0, AV_INPUT_BUFFER_PADDING_SIZE);
  
  
  
  printf("Decode video file %s to %s\n", [filename cStringUsingEncoding:NSUTF8StringEncoding], [outfilename cStringUsingEncoding:NSUTF8StringEncoding]);
  
  /* find the h264 video decoder */
  
  codec = avcodec_find_decoder(AV_CODEC_ID_MPEG4);
  
  if (!codec) {
  
      fprintf(stderr, "Codec not found\n");
  
      exit(1);
  
  }
  
  c = avcodec_alloc_context3(codec);
  
  if (!c) {
  
      fprintf(stderr, "Could not allocate video codec context\n");
  
      exit(1);
  
  }
  
  if (codec->capabilities & AV_CODEC_CAP_TRUNCATED)
  
      c->flags |= AV_CODEC_FLAG_TRUNCATED; // we do not send complete frames
  
  /* For some codecs, such as msmpeg4 and mpeg4, width and height
  
   MUST be initialized there because this information is not
  
   available in the bitstream. */
  
  /* open it */
  
  if (avcodec_open2(c, codec, NULL) < 0) {
  
      fprintf(stderr, "Could not open codec\n");
  
      exit(1);
  
  }
  
  f = fopen([filename cStringUsingEncoding:NSUTF8StringEncoding], "rb");
  
  if (!f) {
  
      fprintf(stderr, "Could not open %s\n", [filename cStringUsingEncoding:NSUTF8StringEncoding]);
  
      exit(1);
  
  }
  
  frame = av_frame_alloc();
  
  if (!frame) {
  
      fprintf(stderr, "Could not allocate video frame\n");
  
      exit(1);
  
  }
  
  frame_count = 0;
  
  
  
  parser = av_parser_init(codec->id);
  
  if (!parser) {
  
      fprintf(stderr, "parser not found\n");
  
      exit(1);
  
  }
  
  
  
  while (!feof(f)) {
  
      /* read raw data from the input file */
  
      data_size = fread(inbuf, 1, INBUF_SIZE, f);
  
      if (!data_size)
  
          break;
  
      /* use the parser to split the data into frames */
  
      data = inbuf;
  
      while (data_size > 0) {
  
          int ret = av_parser_parse2(parser, c, &avpkt->data, &avpkt->size, data, data_size, AV_NOPTS_VALUE, AV_NOPTS_VALUE, 0);
  
          if (ret < 0) {
  
              fprintf(stderr, "Error while parsing\n");
  
              exit(1);
  
          }
  
          data      += ret;
  
          data_size -= ret;
  
          if (avpkt->size){
  
              char buf[1024];
  
  
  
              ret = avcodec_send_packet(c, avpkt);
  
              if (ret < 0) {
  
  
  
                  fprintf(stderr, "Error sending a packet for decoding\n");
  
                  continue;
  
                  exit(1);
  
              }
  
  
  
              while (ret >= 0) {
  
                  ret = avcodec_receive_frame(c, frame);
  
                  if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF){
  
                      char e [1024];
  
                      av_strerror(ret, e, 1024);
  
                      fprintf(stderr, "Fail: %s !\n", e);
  
  // ~~~~~~~~ This is where my program exits ~~~~~~~~~~~~~~~~~~~~~~~~~~~
  
                      return;
  
                  }
  
                  else if (ret < 0) {
  
                      fprintf(stderr, "Error during decoding\n");
  
                      exit(1);
  
                  }
  
              }
  
  
  
  
  
          }
  
      }
  
  }
  
  /* some codecs, such as MPEG, transmit the I and P frame with a
  
   latency of one frame. You must do the following to have a
  
   chance to get the last frame of the video */
  
  
  
  fclose(f);
  
  avcodec_close(c);
  
  av_free(c);
  
  av_frame_free(&frame);
  
  printf("\n");

  }

• Increase Duration of a video FFMPEG C++

  9 avril 2015, par Shahroz Tariq

  I am using the code from the samples of FFmpeg which encodes a picture into a video. All I want to do is to give it a series of pictures and it gives me a video with each picture is taking one second`Code below is just taking one picture from my file system & creating video from it

  AVCodec *codec;
  
  AVCodecContext *c = NULL;
  
  int i, ret, x, y, got_output;
  
  FILE *f;
  
  
  
  AVPacket pkt;
  
  uint8_t endcode[] = { 0, 0, 1, 0xb7 };
  
  
  
  printf("Encode video file %s\n", filename);
  
  
  
  /* find the mpeg1 video encoder */
  
  codec = avcodec_find_encoder((AVCodecID)codec_id);
  
  if (!codec)
  
  {
  
      fprintf(stderr, "Codec not found\n");
  
      exit(1);
  
  }
  
  
  
  c = avcodec_alloc_context3(codec);
  
  if (!c)
  
  {
  
      fprintf(stderr, "Could not allocate video codec context\n");
  
      exit(1);
  
  }
  
  
  
  /* put sample parameters */
  
  c->bit_rate = 400000;
  
  /* resolution must be a multiple of two */
  
  c->width = 200;
  
  c->height = 200;
  
  /* frames per second */
  
  AVRational rational;
  
  rational.num = 1;
  
  rational.den = 25;
  
  c->time_base = rational;
  
  /* 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 */
  
  if (avcodec_open2(c, codec, NULL) < 0)
  
  {
  
      fprintf(stderr, "Could not open codec\n");
  
      exit(1);
  
  }
  
  
  
  fopen_s(&f, filename, "wb");
  
  if (!f)
  
  {
  
      fprintf(stderr, "Could not open %s\n", filename);
  
      exit(1);
  
  }
  
  AVFrame *frame = OpenImage("..\\..\\..\\..\\..\\..\\1.jpg");
  
  //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;
  
  /* the image can be allocated by any means and av_image_alloc() is
  
  * just the most convenient way if av_malloc() is to be used */
  
  
  
  int screenHeight = 200;
  
  int screenWidth = 200;
  
  for (i = 0; i < 25; i++)
  
  {
  
      av_init_packet(&pkt);
  
      pkt.data = NULL;    // packet data will be allocated by the encoder
  
      pkt.size = 0;
  
  
  
      fflush(stdout);
  
  
  
  
  
  
  
      frame->pts = i;
  
  
  
      /* encode the image */
  
      ret = avcodec_encode_video2(c, &pkt, frame, &got_output);
  
      if (ret < 0)
  
      {
  
          fprintf(stderr, "Error encoding frame\n");
  
          exit(1);
  
      }
  
  
  
      if (got_output)
  
      {
  
          printf("Write frame %3d (size=%5d)\n", i, pkt.size);
  
          fwrite(pkt.data, 1, pkt.size, f);
  
          av_free_packet(&pkt);
  
      }
  
  }
  
  
  
  /* get the delayed frames */
  
  for (got_output = 1; got_output; i++)
  
  {
  
      fflush(stdout);
  
  
  
      ret = avcodec_encode_video2(c, &pkt, NULL, &got_output);
  
      if (ret < 0)
  
      {
  
          fprintf(stderr, "Error encoding frame\n");
  
          exit(1);
  
      }
  
  
  
      if (got_output)
  
      {
  
          printf("Write frame %3d (size=%5d)\n", i, pkt.size);
  
          fwrite(pkt.data, 1, pkt.size, f);
  
          av_free_packet(&pkt);
  
      }
  
  }
  
  
  
  /* add sequence end code to have a real mpeg file */
  
  fwrite(endcode, 1, sizeof(endcode), f);
  
  fclose(f);
  
  
  
  avcodec_close(c);
  
  av_free(c);
  
  av_freep(&frame->data[0]);
  
  av_frame_free(&frame);
  
  printf("\n");`