diff options
| author | Ganesh Ajjanagadde <gajjanagadde@gmail.com> | 2015-10-09 22:59:04 +0300 |
|---|---|---|
| committer | Michael Niedermayer <michael@niedermayer.cc> | 2015-10-10 15:43:22 +0300 |
| commit | 979572365f2133f969f3f49ec6a99cc8739d2eba (patch) | |
| tree | f88ea2f8fedeb946846af5d9219bdca8f91b4db8 /libavcodec/ac3enc.c | |
| parent | c4e23ca8537701a38427f90b2dd72eb681d011d6 (diff) | |
avcodec/ac3enc: fix undefined negative left shift
This should fix the undefined behavior reported in:
https://trac.ffmpeg.org/ticket/4727.
I can reproduce this at runtime: simply stick in an abort call in
asym_quant to check if c < 0 and run FATE. I don't know ac3 so I can't
confirm if negative coefficients are intentional, but at the moment they
clearly are according to FATE.
This resolves the undefined behavior. Tested with FATE.
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Diffstat (limited to 'libavcodec/ac3enc.c')
| -rw-r--r-- | libavcodec/ac3enc.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/libavcodec/ac3enc.c b/libavcodec/ac3enc.c index 35e721a964..c8a0caa194 100644 --- a/libavcodec/ac3enc.c +++ b/libavcodec/ac3enc.c @@ -1183,7 +1183,7 @@ static inline int asym_quant(int c, int e, int qbits) { int m; - c = (((c << e) >> (24 - qbits)) + 1) >> 1; + c = (((c * (1<<e)) >> (24 - qbits)) + 1) >> 1; m = (1 << (qbits-1)); if (c >= m) c = m - 1; |