[mad-dev] Calculation error

[Tim Dylla]

Andre schrieb:
> Tim Dylla <tim.dylla at gmx.net> wrote:
>> MAD in contrast introduces a perceivable error right on the first
>> half wave of the sine sweep. I think, it's an overflow in the
>> requantization or the IMDCT (when I remember right, the huffman
>> decoder produces very high output at this moment).
> 
> Just a hunch, but if you are able to build MAD from source, maybe you
> could try the follow patch posted to the list a few years back...
> perhaps it helps ??
> 
> diff -ruN mad-0.14.2b_orig/libmad/layer3.c
> mad-0.14.2b/libmad/layer3.c
> --- mad-0.14.2b_orig/libmad/layer3.c	Thu Nov  8 15:28:02 2001
> +++ mad-0.14.2b/libmad/layer3.c	Tue Mar 25 15:21:12 2003
> @@ -910,7 +910,7 @@
>        fprintf(stderr, "requantize overflow (%f * 2^%d)\n",
>  	      mad_f_todouble(requantized), exp);
>  # endif
> -      requantized = MAD_F_MAX;
> +      requantized = MAD_F_MAX / 2;
>      }
>      else
>        requantized <<= exp;

Nope, same Result. I'm sorry, I'm still sticking with my diploma, so I 
don't have the time for extensive tests right now. Maybe someone can 
confirm the problem and have a look at? Feel free to contact me for the 
Bitstream in Question and the correct decoder output.

Best,

	Tim Dylla


> 
> 
> Andre
> --
> 
>