X-Git-Url: http://git.tdb.fi/?a=blobdiff_plain;f=source%2Fsounddecoder.h;h=20b9d0fb7f4e3d6afa4bd2d9a3dc8806e5477c5e;hb=HEAD;hp=ee5b07d5f33abea2410dc95076f026c0586a1ffc;hpb=35b092aaa718dcb12933effd33324bda5d3b5cce;p=libs%2Fal.git

diff --git a/source/sounddecoder.h b/source/sounddecoder.h
index ee5b07d..20b9d0f 100644
--- a/source/sounddecoder.h
+++ b/source/sounddecoder.h
@@ -17,8 +17,7 @@ public:
 
 
 /**
-This class facilitates loading sound files.  Currently only Ogg Vorbis is
-supported.
+Base class for sound decoders.
 */
 class SoundDecoder
 {
@@ -34,15 +33,29 @@ protected:
 public:
 	virtual ~SoundDecoder();
 
+	/** Opens a file and creates a decoder of an appropriate type for it. */
 	static SoundDecoder *open_file(const std::string &);
+
+	/** Creates a decoder for an already-opened audio file. */
 	static SoundDecoder *open_io(IO::Seekable &);
 
-	virtual void rewind() = 0;
+	/** Restarts decoding from the beginning of the file. */
+	virtual void rewind() { seek(0); }
+
+	/** Sets decoding position expressed in PCM bytes.  This may involve seeking
+	to the beginning and skipping until the desired position is reached.*/
+	virtual void seek(unsigned) = 0;
+
+	/** Reads decoded sound data.  Length is specified in bytes. */
 	virtual unsigned read(char *, unsigned) = 0;
+
 	bool eof() const { return eof_flag; }
 
 	Format get_format() const { return format; }
 	unsigned get_frequency() const { return freq; }
+
+	/** Returns the total length of the sound data in bytes.  Some decoders may
+	not be able to provide this information. */
 	unsigned get_size() const { return size; }
 };