diff --git a/src/decoder/plugins/OggSyncState.hxx b/src/decoder/plugins/OggSyncState.hxx
index 478021475..60379f8c6 100644
--- a/src/decoder/plugins/OggSyncState.hxx
+++ b/src/decoder/plugins/OggSyncState.hxx
@@ -33,12 +33,11 @@
 class OggSyncState {
 	ogg_sync_state oy;
 
-	InputStream &is;
-	Decoder *const decoder;
+	Reader &reader;
 
 public:
-	OggSyncState(InputStream &_is, Decoder *const _decoder=nullptr)
-		:is(_is), decoder(_decoder) {
+	explicit OggSyncState(Reader &_reader)
+		:reader(_reader) {
 		ogg_sync_init(&oy);
 	}
 
@@ -51,27 +50,27 @@ public:
 	}
 
 	bool Feed(size_t size) {
-		return OggFeed(oy, decoder, is, size);
+		return OggFeed(oy, reader, size);
 	}
 
 	bool ExpectPage(ogg_page &page) {
-		return OggExpectPage(oy, page, decoder, is);
+		return OggExpectPage(oy, page, reader);
 	}
 
 	bool ExpectFirstPage(ogg_stream_state &os) {
-		return OggExpectFirstPage(oy, os, decoder, is);
+		return OggExpectFirstPage(oy, os, reader);
 	}
 
 	bool ExpectPageIn(ogg_stream_state &os) {
-		return OggExpectPageIn(oy, os, decoder, is);
+		return OggExpectPageIn(oy, os, reader);
 	}
 
 	bool ExpectPageSeek(ogg_page &page) {
-		return OggExpectPageSeek(oy, page, decoder, is);
+		return OggExpectPageSeek(oy, page, reader);
 	}
 
 	bool ExpectPageSeekIn(ogg_stream_state &os) {
-		return OggExpectPageSeekIn(oy, os, decoder, is);
+		return OggExpectPageSeekIn(oy, os, reader);
 	}
 };
 
diff --git a/src/decoder/plugins/OggUtil.cxx b/src/decoder/plugins/OggUtil.cxx
index d72412024..a5bf3976c 100644
--- a/src/decoder/plugins/OggUtil.cxx
+++ b/src/decoder/plugins/OggUtil.cxx
@@ -19,18 +19,16 @@
 
 #include "config.h"
 #include "OggUtil.hxx"
-#include "../DecoderAPI.hxx"
+#include "fs/io/Reader.hxx"
 
 bool
-OggFeed(ogg_sync_state &oy, Decoder *decoder,
-	InputStream &input_stream, size_t size)
+OggFeed(ogg_sync_state &oy, Reader &reader, size_t size)
 {
 		char *buffer = ogg_sync_buffer(&oy, size);
 		if (buffer == nullptr)
 			return false;
 
-		size_t nbytes = decoder_read(decoder, input_stream,
-					     buffer, size);
+		size_t nbytes = reader.Read(buffer, size);
 		if (nbytes == 0)
 			return false;
 
@@ -39,25 +37,23 @@ OggFeed(ogg_sync_state &oy, Decoder *decoder,
 }
 
 bool
-OggExpectPage(ogg_sync_state &oy, ogg_page &page,
-	      Decoder *decoder, InputStream &input_stream)
+OggExpectPage(ogg_sync_state &oy, ogg_page &page, Reader &reader)
 {
 	while (true) {
 		int r = ogg_sync_pageout(&oy, &page);
 		if (r != 0)
 			return r > 0;
 
-		if (!OggFeed(oy, decoder, input_stream, 1024))
+		if (!OggFeed(oy, reader, 1024))
 			return false;
 	}
 }
 
 bool
-OggExpectFirstPage(ogg_sync_state &oy, ogg_stream_state &os,
-		   Decoder *decoder, InputStream &is)
+OggExpectFirstPage(ogg_sync_state &oy, ogg_stream_state &os, Reader &reader)
 {
 	ogg_page page;
-	if (!OggExpectPage(oy, page, decoder, is))
+	if (!OggExpectPage(oy, page, reader))
 		return false;
 
 	ogg_stream_init(&os, ogg_page_serialno(&page));
@@ -66,11 +62,10 @@ OggExpectFirstPage(ogg_sync_state &oy, ogg_stream_state &os,
 }
 
 bool
-OggExpectPageIn(ogg_sync_state &oy, ogg_stream_state &os,
-		Decoder *decoder, InputStream &is)
+OggExpectPageIn(ogg_sync_state &oy, ogg_stream_state &os, Reader &reader)
 {
 	ogg_page page;
-	if (!OggExpectPage(oy, page, decoder, is))
+	if (!OggExpectPage(oy, page, reader))
 		return false;
 
 	ogg_stream_pagein(&os, &page);
@@ -78,8 +73,7 @@ OggExpectPageIn(ogg_sync_state &oy, ogg_stream_state &os,
 }
 
 bool
-OggExpectPageSeek(ogg_sync_state &oy, ogg_page &page,
-		  Decoder *decoder, InputStream &input_stream)
+OggExpectPageSeek(ogg_sync_state &oy, ogg_page &page, Reader &reader)
 {
 	size_t remaining_skipped = 32768;
 
@@ -100,17 +94,16 @@ OggExpectPageSeek(ogg_sync_state &oy, ogg_page &page,
 			continue;
 		}
 
-		if (!OggFeed(oy, decoder, input_stream, 1024))
+		if (!OggFeed(oy, reader, 1024))
 			return false;
 	}
 }
 
 bool
-OggExpectPageSeekIn(ogg_sync_state &oy, ogg_stream_state &os,
-		    Decoder *decoder, InputStream &is)
+OggExpectPageSeekIn(ogg_sync_state &oy, ogg_stream_state &os, Reader &reader)
 {
 	ogg_page page;
-	if (!OggExpectPageSeek(oy, page, decoder, is))
+	if (!OggExpectPageSeek(oy, page, reader))
 		return false;
 
 	ogg_stream_pagein(&os, &page);
diff --git a/src/decoder/plugins/OggUtil.hxx b/src/decoder/plugins/OggUtil.hxx
index 887a34f01..6fb477acb 100644
--- a/src/decoder/plugins/OggUtil.hxx
+++ b/src/decoder/plugins/OggUtil.hxx
@@ -26,8 +26,7 @@
 
 #include <stddef.h>
 
-class InputStream;
-struct Decoder;
+class Reader;
 
 /**
  * Feed data from the #InputStream into the #ogg_sync_state.
@@ -35,8 +34,7 @@ struct Decoder;
  * @return false on error or end-of-file
  */
 bool
-OggFeed(ogg_sync_state &oy, Decoder *decoder, InputStream &is,
-	size_t size);
+OggFeed(ogg_sync_state &oy, Reader &reader, size_t size);
 
 /**
  * Feed into the #ogg_sync_state until a page gets available.  Garbage
@@ -45,8 +43,7 @@ OggFeed(ogg_sync_state &oy, Decoder *decoder, InputStream &is,
  * @return true if a page is available
  */
 bool
-OggExpectPage(ogg_sync_state &oy, ogg_page &page,
-	      Decoder *decoder, InputStream &is);
+OggExpectPage(ogg_sync_state &oy, ogg_page &page, Reader &reader);
 
 /**
  * Combines OggExpectPage(), ogg_stream_init() and
@@ -56,8 +53,7 @@ OggExpectPage(ogg_sync_state &oy, ogg_page &page,
  * delivered to it
  */
 bool
-OggExpectFirstPage(ogg_sync_state &oy, ogg_stream_state &os,
-		   Decoder *decoder, InputStream &is);
+OggExpectFirstPage(ogg_sync_state &oy, ogg_stream_state &os, Reader &reader);
 
 /**
  * Combines OggExpectPage() and ogg_stream_pagein().
@@ -65,15 +61,13 @@ OggExpectFirstPage(ogg_sync_state &oy, ogg_stream_state &os,
  * @return true if a page was delivered to the stream
  */
 bool
-OggExpectPageIn(ogg_sync_state &oy, ogg_stream_state &os,
-		Decoder *decoder, InputStream &is);
+OggExpectPageIn(ogg_sync_state &oy, ogg_stream_state &os, Reader &reader);
 
 /**
  * Like OggExpectPage(), but allow skipping garbage (after seeking).
  */
 bool
-OggExpectPageSeek(ogg_sync_state &oy, ogg_page &page,
-		  Decoder *decoder, InputStream &is);
+OggExpectPageSeek(ogg_sync_state &oy, ogg_page &page, Reader &reader);
 
 /**
  * Combines OggExpectPageSeek() and ogg_stream_pagein().
@@ -81,7 +75,6 @@ OggExpectPageSeek(ogg_sync_state &oy, ogg_page &page,
  * @return true if a page was delivered to the stream
  */
 bool
-OggExpectPageSeekIn(ogg_sync_state &oy, ogg_stream_state &os,
-		    Decoder *decoder, InputStream &is);
+OggExpectPageSeekIn(ogg_sync_state &oy, ogg_stream_state &os, Reader &reader);
 
 #endif
diff --git a/src/decoder/plugins/OpusDecoderPlugin.cxx b/src/decoder/plugins/OpusDecoderPlugin.cxx
index df16eae37..aeffeb488 100644
--- a/src/decoder/plugins/OpusDecoderPlugin.cxx
+++ b/src/decoder/plugins/OpusDecoderPlugin.cxx
@@ -25,6 +25,8 @@
 #include "OggFind.hxx"
 #include "OggSyncState.hxx"
 #include "../DecoderAPI.hxx"
+#include "decoder/Reader.hxx"
+#include "input/Reader.hxx"
 #include "OggCodec.hxx"
 #include "tag/TagHandler.hxx"
 #include "tag/TagBuilder.hxx"
@@ -205,7 +207,8 @@ LoadEOSPacket(InputStream &is, Decoder *decoder, int serialno,
 
 	/* create temporary Ogg objects for seeking and parsing the
 	   EOS packet */
-	OggSyncState oy(is, decoder);
+	DecoderReader reader(decoder, is);
+	OggSyncState oy(reader);
 	ogg_stream_state os;
 	ogg_stream_init(&os, serialno);
 
@@ -406,7 +409,8 @@ mpd_opus_stream_decode(Decoder &decoder,
 	input_stream.LockRewind(IgnoreError());
 
 	MPDOpusDecoder d(decoder, input_stream);
-	OggSyncState oy(input_stream, &decoder);
+	DecoderReader reader(decoder, input_stream);
+	OggSyncState oy(reader);
 
 	if (!d.ReadFirstPage(oy))
 		return;
@@ -434,7 +438,8 @@ static bool
 mpd_opus_scan_stream(InputStream &is,
 		     const TagHandler &handler, void *handler_ctx)
 {
-	OggSyncState oy(is);
+	InputStreamReader reader(is);
+	OggSyncState oy(reader);
 
 	ogg_stream_state os;
 	if (!oy.ExpectFirstPage(os))