On 09/18/2012 01:42 AM, Måns Rullgård wrote:
Benjamin Larsson<[email protected]>  writes:

gcc:
libavcodec/aacsbr.c:399:8: warning: ‘max_qmf_subbands’ may be used 
uninitialized in this function [-Wuninitialized]
libavcodec/aacsbr.c:326:24: note: ‘max_qmf_subbands’ was declared here

clang:
libavcodec/aacsbr.c:391:16: warning: variable 'max_qmf_subbands' is used 
uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
     } else if (sbr->sample_rate>= 48000)
                ^~~~~~~~~~~~~~~~~~~~~~~~~
libavcodec/aacsbr.c:394:33: note: uninitialized use occurs here
     if (sbr->k[2] - sbr->k[0]>  max_qmf_subbands) {
                                 ^~~~~~~~~~~~~~~~

Reorder and change the if else block so that the max_qmf_subbands
variable always will be set. This change is valid as the only allowed
sample rate betwen 32000 and 48000 is 41000.
---
  libavcodec/aacsbr.c |    6 +++---
  1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/libavcodec/aacsbr.c b/libavcodec/aacsbr.c
index 5eca115..35e7c72 100644
--- a/libavcodec/aacsbr.c
+++ b/libavcodec/aacsbr.c
@@ -386,10 +386,10 @@ static int sbr_make_f_master(AACContext *ac, 
SpectralBandReplication *sbr,
      // Requirements (14496-3 sp04 p205)
      if (sbr->sample_rate<= 32000) {
          max_qmf_subbands = 48;
-    } else if (sbr->sample_rate == 44100) {
-        max_qmf_subbands = 35;
-    } else if (sbr->sample_rate>= 48000)
+    } else if (sbr->sample_rate>= 48000) {
          max_qmf_subbands = 32;
+    } else /*if (sbr->sample_rate == 44100) */
+        max_qmf_subbands = 35;
Might be clearer:

if (sbr->sample_rate<= 32000) {
     max_qmf_subbands = 48;
} else if (sbr->sample_rate<  48000) {
     max_qmf_subbands = 35;
} else {
     max_qmf_subbands = 32;
}


The specifications use this strange range construct. I prefer to keep it resembling the spec. But either way is fine by me.

MvH
Benjamin Larsson
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