On 04/16/2011 08:59 AM, Måns Rullgård wrote: > Justin Ruggles <[email protected]> writes: > >> --- >> This patch will also need a change to ff_ac3_extract_exponents_neon(). Mans, >> could you help me out with that? >> >> -Justin >> >> libavcodec/ac3dsp.c | 4 +++- >> 1 files changed, 3 insertions(+), 1 deletions(-) >> >> >> diff --git a/libavcodec/ac3dsp.c b/libavcodec/ac3dsp.c >> index dccad3b..e3ca37e 100644 >> --- a/libavcodec/ac3dsp.c >> +++ b/libavcodec/ac3dsp.c >> @@ -164,8 +164,10 @@ static void ac3_extract_exponents_c(uint8_t *exp, >> int32_t *coef, int nb_coefs) >> if (e >= 24) { >> e = 24; >> coef[i] = 0; >> + } else if (e < 0) { >> + e = 0; >> + coef[i] = av_clip(coef[i], -16777215, 16777215); >> } >> - av_assert2(e >= 0); >> } >> exp[i] = e; >> } > > Does some other change you have planned make this condition possible? I > assume from the assert() that it was impossible before.
Well, I don't think it is impossible currently. If either the input samples or the MDCT coefficients are outside of [-1.0,1.0] the scaling will put it out of the exponent range. Even if the scaled coefficients are 25-bit signed, the low value will generate an exponent of -1. This function will also be used for coupling coordinates, and in that case they can definitely be out-of-range unless they're clipped prior to this. The coordinates are a ratio of 1 channel to the sum of multiple channels, divided by 8. So if the ratio is >8 (rare but definitely possible) the coordinate will need to be clipped to the valid range at some point. -Justin _______________________________________________ libav-devel mailing list [email protected] https://lists.libav.org/mailman/listinfo/libav-devel
