avcodec/g723_1: fix writing into input frame data and warning

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

libavcodec/g723_1.c

@@ -2346,11 +2346,15 @@ static int g723_1_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
     int16_t weighted_lpc[LPC_ORDER * SUBFRAMES << 1];
     int16_t vector[FRAME_LEN + PITCH_MAX];
     int offset, ret;
-    int16_t *in = (const int16_t *)frame->data[0];
+    int16_t *in_orig = av_memdup(frame->data[0], frame->nb_samples * sizeof(int16_t));
+    int16_t *in = in_orig;
 
     HFParam hf[4];
     int i, j;
 
+    if (!in)
+        return AVERROR(ENOMEM);
+
     highpass_filter(in, &p->hpf_fir_mem, &p->hpf_iir_mem);
 
     memcpy(vector, p->prev_data, HALF_FRAME_LEN * sizeof(int16_t));
@@ -2456,6 +2460,8 @@ static int g723_1_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
         offset += LPC_ORDER;
     }
 
+    av_freep(&in_orig); in = NULL;
+
     if ((ret = ff_alloc_packet2(avctx, avpkt, 24)) < 0)
         return ret;