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• Undefined reference, using FFMpeg-library (AvCodec) on Ubuntu, 64-bits system

  5 mai 2012, par Anders Branderud

  I am running the example code of the latest FFMpeg-library.
  I have inserted the example code into the file videofecencoder.c :

  /*
  
  * copyright (c) 2001 Fabrice Bellard
  
  *
  
  * This file is part of Libav.
  
  *
  
  * Libav is free software; you can redistribute it and/or
  
  * modify it under the terms of the GNU Lesser General Public
  
  * License as published by the Free Software Foundation; either
  
  * version 2.1 of the License, or (at your option) any later version.
  
  *
  
  * Libav is distributed in the hope that it will be useful,
  
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  
  * Lesser General Public License for more details.
  
  *
  
  * You should have received a copy of the GNU Lesser General Public
  
  * License along with Libav; if not, write to the Free Software
  
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  
  */
  
  #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
  
  
  
  
  
  #include 
  
  #include 
  
  #include 
  
  
  
  #ifdef HAVE_AV_CONFIG_H
  
  #undef HAVE_AV_CONFIG_H
  
  #endif
  
  
  
  #include "libavutil/imgutils.h"
  
  #include "libavutil/opt.h"
  
  #include "libavcodec/avcodec.h"
  
  #include "libavutil/mathematics.h"
  
  #include "libavutil/samplefmt.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, int codec_id)
  
  {
  
     AVCodec *codec;
  
     AVCodecContext *c= NULL;
  
     int i, out_size, size, x, y, outbuf_size;
  
     FILE *f;
  
     AVFrame *picture;
  
     uint8_t *outbuf;
  
     int nrOfFramesPerSecond  =25;
  
     int nrOfSeconds =1;
  
  
  
  
  
     printf("Video encoding\n");
  
  
  
     /* find the mpeg1 video encoder */
  
     codec = avcodec_find_encoder((CodecID) codec_id);
  
     if (!codec) {
  
         fprintf(stderr, "codec not found\n");
  
         exit(1);
  
     }
  
  
  
     c = avcodec_alloc_context3(codec);
  
     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;
  
  
  
     if(codec_id == 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);
  
     }
  
  
  
     f = fopen(filename, "wb");
  
     if (!f) {
  
         fprintf(stderr, "could not open %s\n", filename);
  
         exit(1);
  
     }
  
  
  
     /* alloc image and output buffer */
  
     outbuf_size = 100000;
  
     outbuf = (uint8_t*) malloc(outbuf_size);
  
  
  
     /* 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 */
  
     av_image_alloc(picture->data, picture->linesize,
  
                    c->width, c->height, c->pix_fmt, 1);
  
  
  
     /* encode 1 second of video */
  
     int nrOfFramesTotal = nrOfFramesPerSecond * nrOfSeconds;
  
  
  
     /* encode 1 second of video */
  
     for(i=0;i < nrOfFramesTotal; i++) {
  
         fflush(stdout);
  
         /* prepare a dummy image */
  
         /* Y */
  
         for(y=0;yheight;y++) {
  
             for(x=0;xwidth;x++) {
  
                 picture->data[0][y * picture->linesize[0] + x] = x + y + i * 3;
  
             }
  
         }
  
  
  
         /* Cb and Cr */
  
         for(y=0;yheight/2;y++) {
  
             for(x=0;xwidth/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(outbuf);
  
  
  
     avcodec_close(c);
  
     av_free(c);
  
     av_free(picture->data[0]);
  
     av_free(picture);
  
     printf("\n");
  
  }
  
  
  
  int main(int argc, char **argv)
  
  {
  
     const char *filename;
  
  
  
     /* register all the codecs */
  
     avcodec_register_all();
  
  
  
     if (argc <= 1) {
  
  
  
         video_encode_example("/grb_1.mpg", CODEC_ID_MPEG1VIDEO);
  
     } else {
  
         filename = argv[1];
  
     }
  
  
  
  
  
     return 0;
  
  }

  When I run gcc videofecencoder.cc -lavcodec I get the following error messages :

  /tmp/ccJg8IDy.o: In function `video_encode_example(char const*, int)':
  
  videofecencoder.cc:(.text+0x35): undefined reference to `avcodec_find_encoder(CodecID)'
  
  videofecencoder.cc:(.text+0x74): undefined reference to `avcodec_alloc_context3(AVCodec*)'
  
  videofecencoder.cc:(.text+0x7d): undefined reference to `avcodec_alloc_frame()'
  
  videofecencoder.cc:(.text+0x113): undefined reference to `av_opt_set(void*, char const*, char const*, int)'
  
  videofecencoder.cc:(.text+0x12b): undefined reference to `avcodec_open2(AVCodecContext*, AVCodec*, AVDictionary**)'
  
  videofecencoder.cc:(.text+0x1f0): undefined reference to `av_image_alloc(unsigned char**, int*, int, int, PixelFormat, int)'
  
  videofecencoder.cc:(.text+0x35c): undefined reference to `avcodec_encode_video(AVCodecContext*, unsigned char*, int, AVFrame const*)'
  
  videofecencoder.cc:(.text+0x3cf): undefined reference to `avcodec_encode_video(AVCodecContext*, unsigned char*, int, AVFrame const*)'
  
  videofecencoder.cc:(.text+0x47c): undefined reference to `avcodec_close(AVCodecContext*)'
  
  videofecencoder.cc:(.text+0x488): undefined reference to `av_free(void*)'
  
  videofecencoder.cc:(.text+0x497): undefined reference to `av_free(void*)'
  
  videofecencoder.cc:(.text+0x4a3): undefined reference to `av_free(void*)'
  
  /tmp/ccJg8IDy.o: In function `main':
  
  videofecencoder.cc:(.text+0x4c3): undefined reference to `avcodec_register_all()'
  
  collect2: ld returnerade avslutningsstatus 1

  The command nm libavcodec.a | grep avcodec_find results in :

  00000000000008e0 T avcodec_find_best_pix_fmt
  
  0000000000000740 T avcodec_find_best_pix_fmt2
  
                   U avcodec_find_encoder
  
  0000000000002ca0 T avcodec_find_decoder
  
  0000000000002cf0 T avcodec_find_decoder_by_name
  
  0000000000002bd0 T avcodec_find_encoder
  
  0000000000002c30 T avcodec_find_encoder_by_name

  I also have another similar error with another library :
  Undefined reference despite linking in OpenFEC-library

  My system : Ubuntu 11, 64-bits machine

  My next step is to try to compile it on VirtualBox with Ubuntu 32 bits (running on a Windows-OS).

• Anomalie #3212 : Problème function gzopen dans librairie PclZip

  16 octobre 2014, par lrt rln

  Oui merci j’avais déjà fait la manip sur mon fichier local .. je remontais le problème pour que la correction soit faite sur http://www.spip.net/spip-dev/INSTALL/spip_loader.php.
  tl ;dr
  Etrange que personne n’ai remonté le pb avant
  ce qui prouve peut-être que :

  •  0% des utilisateurs de spip_loarder utlisaent une Ubuntu64bits
  • il n’y a aucun utilisateur de spip_loader
  • les utilisateurs de spip_loarder font de beaux patchs dans leur garage
  • il n’y a pas d’utilisateur de spip (point troll)

• Podcast : Transform images and audio in a Podcast [on hold]

  27 juin 2013, par Henry Mazza

  Garage Band and others can make podcasts with embedded images to make a slideshow. Is there a way to do this in the command line with tools like ffmpeg ?