[FFmpeg-cvslog] s302m: fix arithmetic exception

[Andreas Cadhalpun]

ffmpeg | branch: release/2.6 | Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com> | Fri Jun 26 19:31:03 2015 +0200| [1d852105c200a313f9db34d2038dca6875a96780] | committer: Andreas Cadhalpun

s302m: fix arithmetic exception

If nb_samples is zero, the bit_rate calculation results in a division by
zero.

Since ff_get_buffer fails if frame->nb_samples is zero, this can be
fixed by moving the bit_rate calculation after that function call.

That also makes it possible to reuse the already calculated
frame->nb_samples value.

Reviewed-by: Michael Niedermayer <michaelni at gmx.at>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>
(cherry picked from commit 04dfbc9441beed93984568c1547f1ed588122627)
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=1d852105c200a313f9db34d2038dca6875a96780
---

 libavcodec/s302m.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/libavcodec/s302m.c b/libavcodec/s302m.c
index 2ce1038..61c0fe8 100644
--- a/libavcodec/s302m.c
+++ b/libavcodec/s302m.c
@@ -79,10 +79,6 @@ static int s302m_parse_frame_header(AVCodecContext *avctx, const uint8_t *buf,
         case 8:
             avctx->channel_layout = AV_CH_LAYOUT_5POINT1_BACK | AV_CH_LAYOUT_STEREO_DOWNMIX;
     }
-    avctx->bit_rate    = 48000 * avctx->channels * (avctx->bits_per_raw_sample + 4) +
-                         32 * (48000 / (buf_size * 8 /
-                                        (avctx->channels *
-                                         (avctx->bits_per_raw_sample + 4))));
 
     return frame_size;
 }
@@ -108,6 +104,8 @@ static int s302m_decode_frame(AVCodecContext *avctx, void *data,
     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
         return ret;
 
+    avctx->bit_rate = 48000 * avctx->channels * (avctx->bits_per_raw_sample + 4) +
+                      32 * 48000 / frame->nb_samples;
     buf_size = (frame->nb_samples * avctx->channels / 2) * block_size;
 
     if (avctx->bits_per_raw_sample == 24) {