split wav_desc in generic_sound_desc

Originally committed as revision 16894 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mxfenc.c

@@ -604,12 +604,13 @@ static void mxf_write_mpegvideo_desc(AVFormatContext *s, AVStream *st)
     put_buffer(pb, *sc->codec_ul, 16);
 }
 
-static void mxf_write_wav_desc(AVFormatContext *s, AVStream *st)
+static void mxf_write_generic_sound_desc(AVFormatContext *s, AVStream *st, const UID key, unsigned size)
 {
     ByteIOContext *pb = s->pb;
 
-    mxf_write_generic_desc(pb, st, mxf_wav_descriptor_key, 93);
+    mxf_write_generic_desc(pb, st, key, size);
 
+    // audio locked
     mxf_write_local_tag(pb, 1, 0x3D02);
     put_byte(pb, 1);
 
@@ -625,6 +626,11 @@ static void mxf_write_wav_desc(AVFormatContext *s, AVStream *st)
     put_be32(pb, st->codec->bits_per_coded_sample);
 }
 
+static void mxf_write_wav_desc(AVFormatContext *s, AVStream *st)
+{
+    mxf_write_generic_sound_desc(s, st, mxf_wav_descriptor_key, 93);
+}
+
 static void mxf_write_package(AVFormatContext *s, enum MXFMetadataSetType type)
 {
     ByteIOContext *pb = s->pb;