decoder/opus: move _scan_stream() code to OggReadPacket()

Makefile.am

@@ -598,6 +598,7 @@ libxiph_a_SOURCES += \
 	src/lib/xiph/OggSyncState.cxx src/lib/xiph/OggSyncState.hxx \
 	src/lib/xiph/OggFind.cxx src/lib/xiph/OggFind.hxx \
 	src/lib/xiph/OggPage.hxx \
+	src/lib/xiph/OggPacket.cxx src/lib/xiph/OggPacket.hxx \
 	src/lib/xiph/OggStreamState.hxx
 endif
 

src/decoder/plugins/OpusDecoderPlugin.cxx

@@ -22,6 +22,7 @@
 #include "OpusDomain.hxx"
 #include "OpusHead.hxx"
 #include "OpusTags.hxx"
+#include "lib/xiph/OggPacket.hxx"
 #include "lib/xiph/OggFind.hxx"
 #include "lib/xiph/OggVisitor.hxx"
 #include "../DecoderAPI.hxx"
@@ -367,6 +368,45 @@ mpd_opus_stream_decode(Decoder &decoder,
 	}
 }
 
+static bool
+ReadAndParseOpusHead(OggSyncState &sync, OggStreamState &stream,
+		     unsigned &channels)
+{
+	ogg_packet packet;
+
+	return OggReadPacket(sync, stream, packet) && packet.b_o_s &&
+		IsOpusHead(packet) &&
+		ScanOpusHeader(packet.packet, packet.bytes, channels) &&
+		audio_valid_channel_count(channels);
+}
+
+static bool
+ReadAndVisitOpusTags(OggSyncState &sync, OggStreamState &stream,
+		     const TagHandler &handler, void *handler_ctx)
+{
+	ogg_packet packet;
+
+	return OggReadPacket(sync, stream, packet) &&
+		IsOpusTags(packet) &&
+		ScanOpusTags(packet.packet, packet.bytes,
+			     nullptr,
+			     handler, handler_ctx);
+}
+
+static void
+VisitOpusDuration(InputStream &is, OggSyncState &sync, OggStreamState &stream,
+		  const TagHandler &handler, void *handler_ctx)
+{
+	ogg_packet packet;
+
+	if (OggSeekFindEOS(sync, stream, packet, is)) {
+		const auto duration =
+			SongTime::FromScale<uint64_t>(packet.granulepos,
+						      opus_sample_rate);
+		tag_handler_invoke_duration(handler, handler_ctx, duration);
+	}
+}
+
 static bool
 mpd_opus_scan_stream(InputStream &is,
 		     const TagHandler &handler, void *handler_ctx)
@@ -380,67 +420,13 @@ mpd_opus_scan_stream(InputStream &is,
 
 	OggStreamState os(first_page);
 
-	/* read at most 64 more pages */
-	unsigned remaining_pages = 64;
+	unsigned channels;
+	if (!ReadAndParseOpusHead(oy, os, channels) ||
+	    !ReadAndVisitOpusTags(oy, os, handler, handler_ctx))
+		return false;
 
-	unsigned remaining_packets = 4;
-
-	bool result = false;
-
-	ogg_packet packet;
-	while (remaining_packets > 0) {
-		int r = os.PacketOut(packet);
-		if (r < 0) {
-			result = false;
-			break;
-		}
-
-		if (r == 0) {
-			if (remaining_pages-- == 0)
-				break;
-
-			if (!oy.ExpectPageIn(os)) {
-				result = false;
-				break;
-			}
-
-			continue;
-		}
-
-		--remaining_packets;
-
-		if (packet.b_o_s) {
-			if (!IsOpusHead(packet))
-				break;
-
-			unsigned channels;
-			if (!ScanOpusHeader(packet.packet, packet.bytes, channels) ||
-			    !audio_valid_channel_count(channels)) {
-				result = false;
-				break;
-			}
-
-			result = true;
-		} else if (!result)
-			break;
-		else if (IsOpusTags(packet)) {
-			if (!ScanOpusTags(packet.packet, packet.bytes,
-					  nullptr,
-					  handler, handler_ctx))
-				result = false;
-
-			break;
-		}
-	}
-
-	if (packet.e_o_s || OggSeekFindEOS(oy, os, packet, is)) {
-		const auto duration =
-			SongTime::FromScale<uint64_t>(packet.granulepos,
-						      opus_sample_rate);
-		tag_handler_invoke_duration(handler, handler_ctx, duration);
-	}
-
-	return result;
+	VisitOpusDuration(is, oy, os, handler, handler_ctx);
+	return true;
 }
 
 static const char *const opus_suffixes[] = {

src/lib/xiph/OggPacket.cxx

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2003-2016 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "OggPacket.hxx"
+#include "OggSyncState.hxx"
+#include "OggStreamState.hxx"
+
+bool
+OggReadPacket(OggSyncState &sync, OggStreamState &stream, ogg_packet &packet)
+{
+	while (true) {
+		if (stream.PacketOut(packet))
+			return true;
+
+		if (!sync.ExpectPageIn(stream))
+			return false;
+	}
+}

src/lib/xiph/OggPacket.hxx

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2003-2016 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_OGG_PACKET_HXX
+#define MPD_OGG_PACKET_HXX
+
+#include "check.h"
+
+#include <ogg/ogg.h>
+
+class OggSyncState;
+class OggStreamState;
+
+/**
+ * Read the next packet.  If necessary, feed more data into
+ * #OggSyncState and feed more pages into #OggStreamState.
+ */
+bool
+OggReadPacket(OggSyncState &sync, OggStreamState &stream, ogg_packet &packet);
+
+#endif