[issue586] Misplaced call to ff_sine_window_init in libavcodec/wma.c is causing garbled audio in decoded WMA streams

[Aurelien Jacobs]

Aurelien Jacobs <[EMAIL PROTECTED]> added the comment:

manfred wrote:

> 
> manfred <[EMAIL PROTECTED]> added the comment:
> 
> The attached patch should fix the problem, maybe it could be more 
> efficent, but it should show the way (sorry, can't add as file, I 
> allways get a error message):
> 
> diff -ur ffmpeg.orig/libavcodec/wma.c ffmpeg/libavcodec/wma.c
> --- ffmpeg.orig/libavcodec/wma.c      2008-08-15 15:51:21.000000000 
> +0200
> +++ ffmpeg/libavcodec/wma.c   2008-08-21 23:24:16.000000000 +0200
> @@ -302,8 +302,22 @@
>      for(i = 0; i < s->nb_block_sizes; i++) {
>          int n;
>          n = 1 << (s->frame_len_bits - i);
> -        ff_sine_window_init(ff_sine_windows[i], n);
> -        s->windows[i] = ff_sine_windows[i];
> +        if( n <= 128 ) {
> +           ff_sine_window_init(ff_sine_windows[0], n);
> +           s->windows[i] = ff_sine_windows[0];
> +        } else if( n <= 256 ) {
> +           ff_sine_window_init(ff_sine_windows[1], n);
> +           s->windows[i] = ff_sine_windows[1];
> +        } else if( n <= 512 ) {
> +           ff_sine_window_init(ff_sine_windows[2], n);
> +           s->windows[i] = ff_sine_windows[2];
> +        } else if( n <= 1024 ) {
> +           ff_sine_window_init(ff_sine_windows[3], n);
> +           s->windows[i] = ff_sine_windows[3];
> +        } else {
> +           ff_sine_window_init(ff_sine_windows[4], n);
> +           s->windows[i] = ff_sine_windows[4];
> +        }
>      }
>  
>      s->reset_block_lengths = 1;

I don't know if your patch is correct or not. But if it is,
then it can easily be simplified:

diff -ur ffmpeg.orig/libavcodec/wma.c ffmpeg/libavcodec/wma.c
--- ffmpeg.orig/libavcodec/wma.c        2008-08-15 15:51:21.000000000 +0200
+++ ffmpeg/libavcodec/wma.c     2008-08-21 23:24:16.000000000 +0200
@@ -302,8 +302,9 @@
     for(i = 0; i < s->nb_block_sizes; i++) {
-        int n;
+        int n, n2;
         n = 1 << (s->frame_len_bits - i);
-        ff_sine_window_init(ff_sine_windows[i], n);
-        s->windows[i] = ff_sine_windows[i];
+        n2 = FFMIN(n>>8, 4);
+        ff_sine_window_init(ff_sine_windows[n2], n);
+        s->windows[i] = ff_sine_windows[n2];
     }

     s->reset_block_lengths = 1;

And note the the FFMIN() is not needed if n is granted to be less
than 2048 (but I have not verified this).

Aurel

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