detect voxware (closes issue39)

Originally committed as revision 9809 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/avcodec.h

@@ -258,6 +258,7 @@ enum CodecID {
     CODEC_ID_MLP,
     CODEC_ID_GSM_MS, /* as found in WAV */
     CODEC_ID_ATRAC3,
+    CODEC_ID_VOXWARE,
 
     /* subtitle codecs */
     CODEC_ID_DVD_SUBTITLE= 0x17000,

libavformat/riff.c

@@ -206,6 +206,7 @@ const AVCodecTag codec_wav_tags[] = {
     { CODEC_ID_IMC, 0x401 },
     { CODEC_ID_GSM_MS, 0x31 },
     { CODEC_ID_ATRAC3, 0x270 },
+    { CODEC_ID_VOXWARE, 0x75 },
 
     /* FIXME: All of the IDs below are not 16 bit and thus illegal. */
     // for NuppelVideo (nuv.c)