ogg_afh: Add a comment about the three vorbis header packets.

With this information at hand, it's easier to understand how the
vorbis packet callback works.

diff --git a/ogg_afh.c b/ogg_afh.c
index 1e389d9e5770f021a2a86aa97e77479709335f92..9dfb028d0a2f9e14dac54cbc5a4ca200cd2dcf6b 100644 (file)
--- a/ogg_afh.c
+++ b/ogg_afh.c
@@ -20,6 +20,20 @@ struct private_vorbis_data {
        vorbis_comment vc;
 };
 
+/*
+ * Vorbis uses three header packets, all of which are required: the
+ * identification header, the comments header, and the setup header.
+ *
+ * The identification header identifies the bitstream as Vorbis. It contains
+ * the Vorbis version and simple audio characteristics of the stream such as
+ * sample rate and number of channels.
+ *
+ * The comment header includes user text comments (tags) and a vendor string
+ * for the application/library that produced the bitstream.
+ *
+ * The setup header includes extensive CODEC setup information as well as the
+ * complete VQ and Huffman codebooks needed for decoding.
+ */
 static int vorbis_packet_callback(ogg_packet *packet, int packet_num,
                __a_unused int serial, struct afh_info *afhi, void *private_data)
 {