[FFmpeg-trac] #8003(undetermined:new): Division by zero at libavcodec/aaccoder.c

[FFmpeg]

#8003: Division by zero at libavcodec/aaccoder.c
-------------------------------------+-------------------------------------
             Reporter:  Suhwan       |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:  git-
  undetermined                       |  master
             Keywords:  ubsan        |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:
 There's a division by zero at libavcodec/aaccoder.c:554 and 556.

 How to reproduce:
 {{{
 % ffmpeg_g -y -r 14 -i tmp.wmv -map 0 -c:v:14 mpeg1video -c:v zmbv
 -disposition:s:19 v210 -disposition:s flv -aframes 10 -ab 45 -ac 9 -b:v
 292k -strict 1 tmp_.mov

 ffmpeg version N-94185-gca576833e4 Copyright (c) 2000-2019 the FFmpeg
 developers
 built with clang version 9.0.0
 }}}

 s->lambda is zero.
 {{{
 543 static void search_for_pns(AACEncContext *s, AVCodecContext *avctx,
 SingleChannelElement *sce
 544 {
 545     FFPsyBand *band;
 546     int w, g, w2, i;
 547     int wlen = 1024 / sce->ics.num_windows;
 548     int bandwidth, cutoff;
 549     float *PNS = &s->scoefs[0*128], *PNS34 = &s->scoefs[1*128];
 550     float *NOR34 = &s->scoefs[3*128];
 551     uint8_t nextband[128];
 552     const float lambda = s->lambda;
 553     const float freq_mult = avctx->sample_rate*0.5f/wlen;
 554     const float thr_mult = NOISE_LAMBDA_REPLACE*(100.0f/lambda);
 555     const float spread_threshold = FFMIN(0.75f,
 NOISE_SPREAD_THRESHOLD*FFMAX(0.5f, lambda/100
 556     const float dist_bias = av_clipf(4.f * 120 / lambda, 0.25f, 4.0f);
 557     const float pns_transient_energy_r = FFMIN(0.7f, lambda / 140.f);

 }}}

--
Ticket URL: <https://trac.ffmpeg.org/ticket/8003>
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