Re: [FFmpeg-devel] [PATCH 1/2] libswresample: Avoid needlessly large on-stack array.

2014-09-06 Thread Reimar Döffinger 
On Wed, Sep 03, 2014 at 10:48:38PM +0200, Michael Niedermayer wrote:
 On Wed, Sep 03, 2014 at 09:40:55PM +0200, Reimar Döffinger wrote:
  We only actually need to use a tiny part of it.
  Unfortunately we seem to have no real test coverage on
  the code, so this is a bit risky.
  
  Signed-off-by: Reimar Döffinger reimar.doeffin...@gmx.de
  ---
   libswresample/rematrix.c | 23 +--
   1 file changed, 17 insertions(+), 6 deletions(-)
 [...]
  @@ -295,10 +296,10 @@ av_cold static int auto_matrix(SwrContext *s)
   av_assert0(0);
   }
   
  -for(out_i=i=0; i64; i++){
  +for(out_i=i=0; iFF_ARRAY_ELEMS(matrix); i++){
   double sum=0;
  -int in_i=0;
  -for(j=0; j64; j++){
  +in_i=0;
  +for(j=0; jFF_ARRAY_ELEMS(matrix[0]); j++){
   s-matrix[out_i][in_i]= matrix[i][j];
   if(matrix[i][j]){
   sum += fabs(matrix[i][j]);
  @@ -310,6 +311,16 @@ av_cold static int auto_matrix(SwrContext *s)
   if(out_ch_layout  (1ULLi))
   out_i++;
   }
  +for (; i  64; i++) {
  +if (in_ch_layout  out_ch_layout  (1ULLi)) {
  +s-matrix[out_i][in_i] = 1.0;
  +maxcoef = FFMAX(maxcoef, 1.0);
  +}
  +if (in_ch_layout  (1ULLi))
  +in_i++;
  +if (out_ch_layout  (1ULLi))
  +out_i++;
  +}
   if(s-rematrix_volume   0)
   maxcoef = -s-rematrix_volume;
 
 if (i and j are small enough)
 s-matrix[out_i][in_i]= matrix[i][j];
 else
 s-matrix[out_i][in_i]= 0
 sum += fabs(s-matrix[out_i][in_i]);
 
 in the first loop should be simpler than a seperate loop

I am a bit undecided on whether the resulting code is really simpler,
but at least the diff is simpler.
I'll send a new patch.
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Re: [FFmpeg-devel] [PATCH 1/2] libswresample: Avoid needlessly large on-stack array.

2014-09-03 Thread Michael Niedermayer 
On Wed, Sep 03, 2014 at 09:40:55PM +0200, Reimar Döffinger wrote:
 We only actually need to use a tiny part of it.
 Unfortunately we seem to have no real test coverage on
 the code, so this is a bit risky.
 
 Signed-off-by: Reimar Döffinger reimar.doeffin...@gmx.de
 ---
  libswresample/rematrix.c | 23 +--
  1 file changed, 17 insertions(+), 6 deletions(-)
[...]
 @@ -295,10 +296,10 @@ av_cold static int auto_matrix(SwrContext *s)
  av_assert0(0);
  }
  
 -for(out_i=i=0; i64; i++){
 +for(out_i=i=0; iFF_ARRAY_ELEMS(matrix); i++){
  double sum=0;
 -int in_i=0;
 -for(j=0; j64; j++){
 +in_i=0;
 +for(j=0; jFF_ARRAY_ELEMS(matrix[0]); j++){
  s-matrix[out_i][in_i]= matrix[i][j];
  if(matrix[i][j]){
  sum += fabs(matrix[i][j]);
 @@ -310,6 +311,16 @@ av_cold static int auto_matrix(SwrContext *s)
  if(out_ch_layout  (1ULLi))
  out_i++;
  }
 +for (; i  64; i++) {
 +if (in_ch_layout  out_ch_layout  (1ULLi)) {
 +s-matrix[out_i][in_i] = 1.0;
 +maxcoef = FFMAX(maxcoef, 1.0);
 +}
 +if (in_ch_layout  (1ULLi))
 +in_i++;
 +if (out_ch_layout  (1ULLi))
 +out_i++;
 +}
  if(s-rematrix_volume   0)
  maxcoef = -s-rematrix_volume;

if (i and j are small enough)
s-matrix[out_i][in_i]= matrix[i][j];
else
s-matrix[out_i][in_i]= 0
sum += fabs(s-matrix[out_i][in_i]);

in the first loop should be simpler than a seperate loop

[...]
-- 
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The educated differ from the uneducated as much as the living from the
dead. -- Aristotle 


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