--- a/audio/decode/ad_spdif.c
+++ b/audio/decode/ad_spdif.c
@@ -165,7 +165,7 @@ static int init_filter(struct dec_audio *da, AVCodec *codec)

-static int write_packet(void *opaque, uint8_t *buf, int buf_size)
+static int write_packet(void *opaque, const uint8_t *buf, int buf_size)
 {
     struct spdif_filter *sf = opaque;