[FFmpeg-cvslog] r20496 - in trunk/libavcodec: lsp.c lsp.h

[vitor]

Author: vitor
Date: Tue Nov 10 05:17:18 2009
New Revision: 20496

Log:
Avoid variable-length array use in ff_acelp_lspd2lpc()

Modified:
   trunk/libavcodec/lsp.c
   trunk/libavcodec/lsp.h

Modified: trunk/libavcodec/lsp.c
==============================================================================
--- trunk/libavcodec/lsp.c	Tue Nov 10 03:51:47 2009	(r20495)
+++ trunk/libavcodec/lsp.c	Tue Nov 10 05:17:18 2009	(r20496)
@@ -157,9 +157,11 @@ static void lsp2polyf(const double *lsp,
 
 void ff_acelp_lspd2lpc(const double *lsp, float *lpc, int lp_half_order)
 {
-    double pa[lp_half_order+1], qa[lp_half_order+1];
+    double pa[MAX_LP_HALF_ORDER+1], qa[MAX_LP_HALF_ORDER+1];
     float *lpc2 = lpc + (lp_half_order << 1) - 1;
 
+    assert(lp_half_order <= MAX_LP_HALF_ORDER);
+
     lsp2polyf(lsp,     pa, lp_half_order);
     lsp2polyf(lsp + 1, qa, lp_half_order);
 

Modified: trunk/libavcodec/lsp.h
==============================================================================
--- trunk/libavcodec/lsp.h	Tue Nov 10 03:51:47 2009	(r20495)
+++ trunk/libavcodec/lsp.h	Tue Nov 10 05:17:18 2009	(r20496)
@@ -80,11 +80,16 @@ void ff_acelp_lsp2lpc(int16_t* lp, const
  */
 void ff_acelp_lp_decode(int16_t* lp_1st, int16_t* lp_2nd, const int16_t* lsp_2nd, const int16_t* lsp_prev, int lp_order);
 
+
+#define MAX_LP_HALF_ORDER 8
+
 /**
  * Reconstructs LPC coefficients from the line spectral pair frequencies.
  *
  * @param lsp line spectral pairs in cosine domain
  * @param lpc linear predictive coding coefficients
+ * @param lp_half_order half the number of the amount of LPCs to be
+ *        reconstructed, need to be smaller or equal to MAX_LP_HALF_ORDER
  *
  * @note buffers should have a minimux size of 2*lp_half_order elements.
  *