avcodec/libopusenc: Use av_mallocz_array()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/libopusenc.c

@@ -277,7 +277,7 @@ static av_cold int libopus_encode_init(AVCodecContext *avctx)
     }
     avctx->extradata_size = header_size;
 
-    opus->samples = av_mallocz(frame_size * avctx->channels *
+    opus->samples = av_mallocz_array(frame_size, avctx->channels *
                                av_get_bytes_per_sample(avctx->sample_fmt));
     if (!opus->samples) {
         av_log(avctx, AV_LOG_ERROR, "Failed to allocate samples buffer.\n");