[Libav-user] avcodec_open seg fault?

Jeremy Graham jgraham at cs.unc.edu
Mon Apr 9 23:11:02 CEST 2012

Thank you for responding, Michael.  I did try using avcodec_open2 as 
well but I still got a seg fault out of it. I set the third parameter to 
NULL, however.  Is that what I am doing wrong?  Should I also be making 
a call to avcodec_init?  I am not doing that currently.

Actually, I will go ahead and try to post what I think is the relevant 
code.  This comes almost directly from the api_example found at this 

//These were declared globally
static uint8_t*  pixbuf_data       = NULL;
static vp_os_mutex_t  video_update_lock = PTHREAD_MUTEX_INITIALIZER;
static AVCodec *codec;
static AVCodecContext *c= NULL;
int out_size, size, outbuf_size;
static FILE *f;
static AVFrame *picture;
static uint8_t *outbuf;
   /* find the mpeg1 video encoder */
      codec = avcodec_find_encoder(CODEC_ID_MPEG1VIDEO);
      if (!codec) {
          fprintf(stderr, "codec not found\n");

      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->pix_fmt = PIX_FMT_YUV420P;

      /* open it */
      if (avcodec_open(c, codec) < 0) {
          fprintf(stderr, "could not open codec\n");


On 04/09/2012 05:01 PM, Michael Bradshaw wrote:
> On Mon, Apr 9, 2012 at 2:56 PM, Jeremy Graham <jgraham at cs.unc.edu 
> <mailto:jgraham at cs.unc.edu>> wrote:
>     Hello, everyone:
>     I just thought that I'd start out by asking a general question.
>      Can anyone tell me the possible reasons why avcodec_open might
>     generate a segementation fault?
> Just out of curiosity, are you using avcodec_open or avcodec_open2? 
> avcodec_open is deprecated and should be avoided if possible.
> --Michael
> _______________________________________________
> Libav-user mailing list
> Libav-user at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/libav-user

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