avcodec/aptxdec: Process data in complete blocks only

The APTX (HD) decoder decodes blocks of four (six) bytes to four
output samples. It makes no sense to handle incomplete blocks:
They would just lead to synchronization errors, in which case
the complete frame is discarded. So only handle complete blocks.
This also avoids reading from the packet's padding and writing
into the frame's padding.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/aptxdec.c

@@ -151,7 +151,7 @@ static int aptx_decode_frame(AVCodecContext *avctx, AVFrame *frame,
     /* get output buffer */
     frame->ch_layout.nb_channels = NB_CHANNELS;
     frame->format = AV_SAMPLE_FMT_S32P;
-    frame->nb_samples = 4 * avpkt->size / s->block_size;
+    frame->nb_samples = 4 * (avpkt->size / s->block_size);
     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
         return ret;