avcodec/dstdec: Use local channels variable

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/dstdec.c

@@ -262,7 +262,7 @@ static int decode_frame(AVCodecContext *avctx, void *data,
         skip_bits1(gb);
         if (get_bits(gb, 6))
             return AVERROR_INVALIDDATA;
-        memcpy(frame->data[0], avpkt->data + 1, FFMIN(avpkt->size - 1, frame->nb_samples * avctx->channels));
+        memcpy(frame->data[0], avpkt->data + 1, FFMIN(avpkt->size - 1, frame->nb_samples * channels));
         goto dsd;
     }
 
@@ -287,7 +287,7 @@ static int decode_frame(AVCodecContext *avctx, void *data,
 
     same_map = get_bits1(gb);
 
-    if ((ret = read_map(gb, &s->fsets, map_ch_to_felem, avctx->channels)) < 0)
+    if ((ret = read_map(gb, &s->fsets, map_ch_to_felem, channels)) < 0)
         return ret;
 
     if (same_map) {
@@ -295,13 +295,13 @@ static int decode_frame(AVCodecContext *avctx, void *data,
         memcpy(map_ch_to_pelem, map_ch_to_felem, sizeof(map_ch_to_felem));
     } else {
         avpriv_request_sample(avctx, "Not Same Mapping");
-        if ((ret = read_map(gb, &s->probs, map_ch_to_pelem, avctx->channels)) < 0)
+        if ((ret = read_map(gb, &s->probs, map_ch_to_pelem, channels)) < 0)
             return ret;
     }
 
     /* Half Probability (10.10) */
 
-    for (ch = 0; ch < avctx->channels; ch++)
+    for (ch = 0; ch < channels; ch++)
         half_prob[ch] = get_bits1(gb);
 
     /* Filter Coef Sets (10.12) */
@@ -325,7 +325,7 @@ static int decode_frame(AVCodecContext *avctx, void *data,
     build_filter(s->filter, &s->fsets);
 
     memset(s->status, 0xAA, sizeof(s->status));
-    memset(dsd, 0, frame->nb_samples * 4 * avctx->channels);
+    memset(dsd, 0, frame->nb_samples * 4 * channels);
 
     ac_get(ac, gb, prob_dst_x_bit(s->fsets.coeff[0][0]), &dst_x_bit);
 
@@ -364,10 +364,10 @@ static int decode_frame(AVCodecContext *avctx, void *data,
     }
 
 dsd:
-    for (i = 0; i < avctx->channels; i++) {
+    for (i = 0; i < channels; i++) {
         ff_dsd2pcm_translate(&s->dsdctx[i], frame->nb_samples, 0,
                              frame->data[0] + i * 4,
-                             avctx->channels * 4, pcm + i, avctx->channels);
+                             channels * 4, pcm + i, channels);
     }
 
     *got_frame_ptr = 1;