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• Anomalie #3128 : Compression CSS et mauvaise interprétation de caractères

  29 décembre 2013, par kent1 -

  De la même manière je viens de me rendre compte que la mise en abolue des urls est également utilisées sur des références à des id

  Par exemple, j’ai besoin de faire en css :
  

      path.area.perspective1_haute,path.area.perspective2_haute
          fill : url( #gradient_perspective1 ) ;
      
  

  Cela permet d’appliquer dans un svg un dégradé défini et référencé par son id "gradient_perspective1".

  Or lors de la compression CSS, le code devient :

  path.area.perspective1_haute,path.area.perspective2_haute
          fill : url( //url_de_la_css/#gradient_perspective1 ) ;
      
  

  En gros comme si c’était une ancre dans la css.

• FFmpeg/libav : YUV420P to RGB conversion

  17 janvier 2014, par learner

  I am working with Video encoding-decoding based on online tutorials. In the encoding section, the dummy image created is in YUV420P format. I need it to be in RGB or BGR format. Any idea how to do this ??

   #include 
  
   #include 
  
   #include 
  
  
  
   #ifdef HAVE_AV_CONFIG_H
  
   #undef HAVE_AV_CONFIG_H
  
   #endif
  
  
  
   #include "libavcodec/avcodec.h"
  
   #include "libavutil/mathematics.h"
  
  
  
   #define INBUF_SIZE 4096
  
   #define AUDIO_INBUF_SIZE 20480
  
   #define AUDIO_REFILL_THRESH 4096
  
  
  
   /*
  
   * Video encoding example
  
   */
  
   static void video_encode_example(const char *filename)
  
   {
  
       AVCodec *codec;
  
       AVCodecContext *c = NULL;
  
       int i, out_size, size, x, y, outbuf_size;
  
       FILE *f;
  
       AVFrame *picture;
  
       uint8_t *outbuf, *picture_buf;
  
  
  
       printf("Video encoding\n");
  
  
  
       /* find the mpeg1 video encoder */
  
       codec = avcodec_find_encoder(CODEC_ID_MPEG1VIDEO);
  
       if (!codec)
  
       {
  
           fprintf(stderr, "codec not found\n");
  
           exit(1);
  
       }
  
  
  
       c = avcodec_alloc_context();
  
       picture = avcodec_alloc_frame();
  
  
  
       /* 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->gop_size = 10; /* emit one intra frame every ten frames */
  
       c->max_b_frames=1;
  
       c->pix_fmt = PIX_FMT_YUV420P;
  
  
  
       /* open it */
  
       if (avcodec_open(c, codec) < 0)
  
       {
  
           fprintf(stderr, "could not open codec\n");
  
           exit(1);
  
       }
  
  
  
       f = fopen(filename, "wb");
  
       if (!f)
  
       {
  
           fprintf(stderr, "could not open file! %s\n", filename);
  
           exit(1);
  
       }
  
  
  
       /* alloc image and output buffer */
  
       outbuf_size = 100000;
  
       outbuf = malloc(outbuf_size);
  
       size = c->width * c->height;
  
       picture_buf = malloc((size * 3) / 2); /* size for YUV 420 */
  
  
  
       picture->data[0] = picture_buf;
  
       picture->data[1] = picture->data[0] + size;
  
       picture->data[2] = picture->data[1] + size / 4;
  
       picture->linesize[0] = c->width;
  
       picture->linesize[1] = c->width / 2;
  
       picture->linesize[2] = c->width / 2;
  
  
  
       /* encode 1 second of video */
  
       for(i=0; i<25; i++)
  
       {
  
           fflush(stdout);
  
           /* prepare a dummy image */
  
           /* Y */
  
           for(y=0; y < c->height; y++)
  
           {
  
               for(x=0; x < c->width; x++)
  
               {
  
                   picture->data[0][y * picture->linesize[0] + x] = x + y + i * 3;
  
               }
  
           }
  
  
  
           /* Cb and Cr */
  
           for(y=0; y < c->height/2; y++)
  
           {
  
               for(x=0; x < c->width/2; x++)
  
               {
  
                   picture->data[1][y * picture->linesize[1] + x] = 128 + y + i * 2;
  
                   picture->data[2][y * picture->linesize[2] + x] = 64 + x + i * 5;
  
               }
  
           }
  
  
  
           /* encode the image */
  
           out_size = avcodec_encode_video(c, outbuf, outbuf_size, picture);
  
           printf("encoding frame %3d (size=%5d)\n", i, out_size);
  
           fwrite(outbuf, 1, out_size, f);
  
       }
  
  
  
       /* get the delayed frames */
  
       for(; out_size; i++)
  
       {
  
           fflush(stdout);
  
  
  
           out_size = avcodec_encode_video(c, outbuf, outbuf_size, NULL);
  
           printf("write frame %3d (size=%5d)\n", i, out_size);
  
           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);
  
       free(picture_buf);
  
       free(outbuf);
  
  
  
       avcodec_close(c);
  
       av_free(c);
  
       av_free(picture);
  
       printf("\n");
  
   }
  
  
  
   /*
  
    * Video decoding example
  
    */
  
  
  
   static void pgm_save(unsigned char *buf, int wrap, int xsize, int ysize,
  
                        char *filename)
  
   {
  
       FILE *f;
  
       int i;
  
  
  
       f=fopen(filename,"w");
  
       fprintf(f,"P5\n%d %d\n%d\n",xsize,ysize,255);
  
       for(i=0; i* set end of buffer to 0 (this ensures that no overreading happens for damaged mpeg streams) */
  
       memset(inbuf + INBUF_SIZE, 0, FF_INPUT_BUFFER_PADDING_SIZE);
  
  
  
       printf("Video decoding\n");
  
  
  
       /* find the mpeg1 video decoder */
  
       codec = avcodec_find_decoder(CODEC_ID_MPEG1VIDEO);
  
       if (!codec) {
  
           fprintf(stderr, "codec not found\n");
  
           exit(1);
  
       }
  
  
  
       c = avcodec_alloc_context();
  
       picture = avcodec_alloc_frame();
  
  
  
       if(codec->capabilities&CODEC_CAP_TRUNCATED)
  
           c->flags|= 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_open(c, codec) < 0) {
  
           fprintf(stderr, "could not open codec\n");
  
           exit(1);
  
       }
  
  
  
       /* the codec gives us the frame size, in samples */
  
  
  
       f = fopen(filename, "rb");
  
       if (!f) {
  
           fprintf(stderr, "could not open file! %s\n", filename);
  
           exit(1);
  
       }
  
  
  
       frame = 0;
  
       for(;;) {
  
           avpkt.size = fread(inbuf, 1, INBUF_SIZE, f);
  
           if (avpkt.size == 0)
  
               break;
  
  
  
           /* NOTE1: some codecs are stream based (mpegvideo, mpegaudio)
  
              and this is the only method to use them because you cannot
  
              know the compressed data size before analysing it.
  
  
  
              BUT some other codecs (msmpeg4, mpeg4) are inherently frame
  
              based, so you must call them with all the data for one
  
              frame exactly. You must also initialize 'width' and
  
              'height' before initializing them. */
  
  
  
           /* NOTE2: some codecs allow the raw parameters (frame size,
  
              sample rate) to be changed at any frame. We handle this, so
  
              you should also take care of it */
  
  
  
           /* here, we use a stream based decoder (mpeg1video), so we
  
              feed decoder and see if it could decode a frame */
  
  
  
           avpkt.data = inbuf;
  
           while (avpkt.size > 0)
  
           {
  
               len = avcodec_decode_video2(c, picture, &got_picture, &avpkt);
  
               if (len < 0)
  
               {
  
                   fprintf(stderr, "Error while decoding frame %d\n", frame);
  
                   exit(1);
  
               }
  
               if (got_picture)
  
               {
  
                   printf("saving frame %3d\n", frame);
  
                   fflush(stdout);
  
  
  
                   /* the picture is allocated by the decoder. no need to
  
                      free it */
  
                   snprintf(buf, sizeof(buf), outfilename, frame);
  
                   pgm_save(picture->data[0], picture->linesize[0],
  
                            c->width, c->height, buf);
  
                   frame++;
  
               }
  
               avpkt.size -= len;
  
               avpkt.data += len;
  
           }
  
       }
  
  
  
       /* 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 */
  
  
  
       avpkt.data = NULL;
  
       avpkt.size = 0;
  
       len = avcodec_decode_video2(c, picture, &got_picture, &avpkt);
  
       if (got_picture)
  
       {
  
           printf("saving last frame %3d\n", frame);
  
           fflush(stdout);
  
  
  
           /* the picture is allocated by the decoder. no need to
  
              free it */
  
           snprintf(buf, sizeof(buf), outfilename, frame);
  
           pgm_save(picture->data[0], picture->linesize[0],
  
                    c->width, c->height, buf);
  
           frame++;
  
       }
  
  
  
       fclose(f);
  
  
  
       avcodec_close(c);
  
       av_free(c);
  
       av_free(picture);
  
       printf("\n");
  
   }
  
  
  
   int main(int argc, char **argv)
  
   {
  
       const char *filename;
  
  
  
       /* must be called before using avcodec lib */
  
       avcodec_init();
  
  
  
       /* register all the codecs */
  
       avcodec_register_all();
  
  
  
       if (argc <= 1)
  
       { 
  
           video_encode_example("asdf.mpg");
  
           filename = "asdf.mpg";
  
       }
  
       else
  
       {
  
           filename = argv[1];
  
       }
  
  
  
       video_decode_example("%d.pgm", filename);
  
  
  
       return 0;
  
  }

  I tried with PIX_FMT_RGB24 and changing each channel accordingly. For this, I declared another :

  AVFrame *pictureRGB ; and then : pictureRGB = avcodec_alloc_frame() ;

  for(y=0; y < c->height; y++)
  
  {
  
       for(x=0; x < c->width; x++)
  
       {
  
            pictureRGB ->data[0][y * pictureRGB ->linesize[0] + x] = x + y + i * 3;
  
            pictureRGB ->data[1][y * pictureRGB ->linesize[1] + x] = x + y + i * 3;
  
            pictureRGB ->data[2][y * pictureRGB ->linesize[2] + x] = x + y + i * 3;
  
       }
  
  }

  But it gives errors ! I am totally new to this library. Is it possible to directly encode as a RGB dummy image rather than as YUV420P. Anybody out there with sound knowledge in this area ??? Thanks in advance !

• Revision 20cf22a128 : Enforce effective motion vector search range This commit explicitly enforces th

  21 janvier 2014, par Jingning Han

  Changed Paths :
   Modify /vp9/encoder/vp9_mcomp.c

  
  
  Enforce effective motion vector search range

  This commit explicitly enforces the effective motion vector range
  in the motion search stage. The range needs to be the intersection
  of UMV border, effective absolute motion vector value range, and
  the target search area.

  Change-Id : I1cf7c563e02b1086040dad6c1f4f6be1538635a6