[vorbis-dev] getting playback length from ogg vorbis file

[Jack Angel]

On Fri, 11 Jul 2003 12:39:29 +0200
Lourens Veen <lourens at rainbowdesert.net> wrote:

> Hold on, that seems to give incorrect results. There is something 
> fishy there with the floor() construction. This seems to work 
> better:
> 
> --- ogginfo2.c.old      Fri Jul 11 12:16:04 2003
> +++ ogginfo2.c  Fri Jul 11 12:36:41 2003
> @@ -373,19 +373,20 @@
>  static void vorbis_end(stream_processor *stream)
>  {
>      misc_vorbis_info *inf = stream->data;
> -    long minutes, seconds;
> +    long minutes, seconds, seconds100;
>      double bitrate, time;
> 
>      time = (double)inf->lastgranulepos / inf->vi.rate;
>      minutes = (long)time / 60;
>      seconds = (long)time - minutes*60;
> +    seconds100 = (long)((time - minutes*60 - seconds)*100.0);
>      bitrate = inf->bytes*8 / time / 1000.0;
> 
>      info(_("Vorbis stream %d:\n"
>             "\tTotal data length: %ld bytes\n"
> -           "\tPlayback length: %ldm:%02lds\n"
> +           "\tPlayback length: %ldm:%02lds.%02ld\n"
>             "\tAverage bitrate: %f kbps\n"),
> -            stream->num,inf->bytes, minutes, seconds, bitrate);
> +            stream->num,inf->bytes, minutes, seconds, seconds100, 
> bitrate);
> 
>      vorbis_comment_clear(&inf->vc);
>      vorbis_info_clear(&inf->vi);
> 
> 
> Also, I understand why this works :-). But I still don't see why
> (long)((time - floor(time) * 100.0) doesn't work...

<p>This doesn't work because <math.h> isn't included, and floor definition is picked up from somewhere else. I don't know from where, but check this:

~# cat test.c
//#include <math.h>

int main()
{
  double time = 800.510;
  printf("%f %f\n", time, floor(time));
}
~# ./test
800.510000 80298907385280950682755444182387957006805762791233118433533549849731864380320828326878948200747786192971450917286372883160777116601003408797083834721392632613345848270168843448871733524979042229249230391219772018492598287395874874133804539689308263302039462290421043577395770761936896.000000

and now:
~# cat test.c 
#include <math.h>

int main()
{
  double time = 800.510;
  printf("%f %f\n", time, floor(time));
}
~# ./test
800.510000 800.000000

<p>It started working fine after including <math.h>
We may include <math.h> and your initial code would be ok, or we could end up with code you wrote now. Also, after thinking a little, i though 1/100 isn't the round number - better use milliseconds. So, i propose this patch to be integrated to vorbistools:

<p><p>diff -r -c vorbis-tools-1.0/ogginfo/ogginfo2.c vorbis-tools-1.0-new/ogginfo/ogginfo2.c
*** vorbis-tools-1.0/ogginfo/ogginfo2.c Fri Jul 19 10:26:54 2002
--- vorbis-tools-1.0-new/ogginfo/ogginfo2.c     Sat Jul 12 03:23:07 2003
***************
*** 373,391 ****
  static void vorbis_end(stream_processor *stream) 
  {
      misc_vorbis_info *inf = stream->data;
!     long minutes, seconds;
      double bitrate, time;
  
      time = (double)inf->lastgranulepos / inf->vi.rate;
      minutes = (long)time / 60;
      seconds = (long)time - minutes*60;
      bitrate = inf->bytes*8 / time / 1000.0;
  
      info(_("Vorbis stream %d:\n"
             "\tTotal data length: %ld bytes\n"
!            "\tPlayback length: %ldm:%02lds\n"
             "\tAverage bitrate: %f kbps\n"), 
!             stream->num,inf->bytes, minutes, seconds, bitrate);
  
      vorbis_comment_clear(&inf->vc);
      vorbis_info_clear(&inf->vi);
--- 373,392 ----
  static void vorbis_end(stream_processor *stream) 
  {
      misc_vorbis_info *inf = stream->data;
!     long minutes, seconds, milliseconds;
      double bitrate, time;
  
      time = (double)inf->lastgranulepos / inf->vi.rate;
      minutes = (long)time / 60;
      seconds = (long)time - minutes*60;
+     milliseconds = (long)((time - minutes*60 - seconds)*1000);
      bitrate = inf->bytes*8 / time / 1000.0;
  
      info(_("Vorbis stream %d:\n"
             "\tTotal data length: %ld bytes\n"
!            "\tPlayback length: %ldm:%02ld.%02lds\n"
             "\tAverage bitrate: %f kbps\n"), 
!             stream->num,inf->bytes, minutes, seconds, milliseconds, bitrate);
  
      vorbis_comment_clear(&inf->vc);
      vorbis_info_clear(&inf->vi);

<p><p><p><p><p>> Lourens
> -- 
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> 
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<p>
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