avformat/mpc: use ff_get_extradata()

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

libavformat/mpc.c

@@ -95,9 +95,8 @@ static int mpc_read_header(AVFormatContext *s)
     st->codec->channel_layout = AV_CH_LAYOUT_STEREO;
     st->codec->bits_per_coded_sample = 16;
 
-    if (ff_alloc_extradata(st->codec, 16))
+    if (ff_get_extradata(st->codec, s->pb, 16) < 0)
         return AVERROR(ENOMEM);
-    avio_read(s->pb, st->codec->extradata, 16);
     st->codec->sample_rate = mpc_rate[st->codec->extradata[2] & 3];
     avpriv_set_pts_info(st, 32, MPC_FRAMESIZE, st->codec->sample_rate);
     /* scan for seekpoints */