diff --git a/NEWS b/NEWS
index 701760f20..0013fcb85 100644
--- a/NEWS
+++ b/NEWS
@@ -17,14 +17,19 @@ ver 0.21 (not yet released)
 
 ver 0.20.12 (not yet released)
 * input
+  - cdio_paranoia, ffmpeg, file, smbclient: reduce lock contention,
+    fixing lots of xrun problems
   - curl: fix seeking
 * decoder
   - ffmpeg: fix GCC 8 warning
   - vorbis: fix Tremor support
 * player
   - log message when decoder is too slow
+* encoder
+  - vorbis: default to quality 3
 * output
   - fix hanging playback with soxr resampler
+  - httpd: flush encoder after tag; fixes corrupt Vorbis stream
 
 ver 0.20.11 (2017/10/18)
 * storage
diff --git a/doc/user.xml b/doc/user.xml
index 4d4add06d..a739046bf 100644
--- a/doc/user.xml
+++ b/doc/user.xml
@@ -3068,8 +3068,8 @@ run</programlisting>
                 </entry>
                 <entry>
                   Sets the quality for VBR.  -1 is the lowest quality,
-                  10 is the highest quality.  Cannot be used with
-                  <varname>bitrate</varname>.
+                  10 is the highest quality.  Defaults to 3.  Cannot
+                  be used with <varname>bitrate</varname>.
                 </entry>
               </row>
               <row>
diff --git a/src/encoder/plugins/VorbisEncoderPlugin.cxx b/src/encoder/plugins/VorbisEncoderPlugin.cxx
index 68ea479ee..5a8e2826a 100644
--- a/src/encoder/plugins/VorbisEncoderPlugin.cxx
+++ b/src/encoder/plugins/VorbisEncoderPlugin.cxx
@@ -62,7 +62,7 @@ private:
 };
 
 class PreparedVorbisEncoder final : public PreparedEncoder {
-	float quality;
+	float quality = 3;
 	int bitrate;
 
 public:
@@ -97,7 +97,7 @@ PreparedVorbisEncoder::PreparedVorbisEncoder(const ConfigBlock &block)
 
 		value = block.GetBlockValue("bitrate");
 		if (value == nullptr)
-			throw std::runtime_error("neither bitrate nor quality defined");
+			return;
 
 		quality = -2.0;
 
diff --git a/src/input/plugins/CdioParanoiaInputPlugin.cxx b/src/input/plugins/CdioParanoiaInputPlugin.cxx
index e48d8f389..2b9bced5e 100644
--- a/src/input/plugins/CdioParanoiaInputPlugin.cxx
+++ b/src/input/plugins/CdioParanoiaInputPlugin.cxx
@@ -270,7 +270,10 @@ CdioParanoiaInputStream::Seek(offset_type new_offset)
 	lsn_relofs = new_offset / CDIO_CD_FRAMESIZE_RAW;
 	offset = new_offset;
 
-	cdio_paranoia_seek(para, lsn_from + lsn_relofs, SEEK_SET);
+	{
+		const ScopeUnlock unlock(mutex);
+		cdio_paranoia_seek(para, lsn_from + lsn_relofs, SEEK_SET);
+	}
 }
 
 size_t
@@ -292,6 +295,8 @@ CdioParanoiaInputStream::Read(void *ptr, size_t length)
 
 		//current sector was changed ?
 		if (lsn_relofs != buffer_lsn) {
+			const ScopeUnlock unlock(mutex);
+
 			rbuf = cdio_paranoia_read(para, nullptr);
 
 			s_err = cdda_errors(drv);
diff --git a/src/input/plugins/FfmpegInputPlugin.cxx b/src/input/plugins/FfmpegInputPlugin.cxx
index f2611c094..781567dac 100644
--- a/src/input/plugins/FfmpegInputPlugin.cxx
+++ b/src/input/plugins/FfmpegInputPlugin.cxx
@@ -104,7 +104,13 @@ input_ffmpeg_open(const char *uri,
 size_t
 FfmpegInputStream::Read(void *ptr, size_t read_size)
 {
-	auto result = avio_read(h, (unsigned char *)ptr, read_size);
+	int result;
+
+	{
+		const ScopeUnlock unlock(mutex);
+		result = avio_read(h, (unsigned char *)ptr, read_size);
+	}
+
 	if (result <= 0) {
 		if (result < 0)
 			throw MakeFfmpegError(result, "avio_read() failed");
@@ -126,7 +132,12 @@ FfmpegInputStream::IsEOF() noexcept
 void
 FfmpegInputStream::Seek(offset_type new_offset)
 {
-	auto result = avio_seek(h, new_offset, SEEK_SET);
+	int64_t result;
+
+	{
+		const ScopeUnlock unlock(mutex);
+		result = avio_seek(h, new_offset, SEEK_SET);
+	}
 
 	if (result < 0)
 		throw MakeFfmpegError(result, "avio_seek() failed");
diff --git a/src/input/plugins/FileInputPlugin.cxx b/src/input/plugins/FileInputPlugin.cxx
index fc51715ad..2d2850c74 100644
--- a/src/input/plugins/FileInputPlugin.cxx
+++ b/src/input/plugins/FileInputPlugin.cxx
@@ -87,14 +87,24 @@ input_file_open(gcc_unused const char *filename,
 void
 FileInputStream::Seek(offset_type new_offset)
 {
-	reader.Seek((off_t)new_offset);
+	{
+		const ScopeUnlock unlock(mutex);
+		reader.Seek((off_t)new_offset);
+	}
+
 	offset = new_offset;
 }
 
 size_t
 FileInputStream::Read(void *ptr, size_t read_size)
 {
-	size_t nbytes = reader.Read(ptr, read_size);
+	size_t nbytes;
+
+	{
+		const ScopeUnlock unlock(mutex);
+		nbytes = reader.Read(ptr, read_size);
+	}
+
 	offset += nbytes;
 	return nbytes;
 }
diff --git a/src/input/plugins/SmbclientInputPlugin.cxx b/src/input/plugins/SmbclientInputPlugin.cxx
index 4b3026e40..b40eadb9a 100644
--- a/src/input/plugins/SmbclientInputPlugin.cxx
+++ b/src/input/plugins/SmbclientInputPlugin.cxx
@@ -125,9 +125,14 @@ input_smbclient_open(const char *uri,
 size_t
 SmbclientInputStream::Read(void *ptr, size_t read_size)
 {
-	smbclient_mutex.lock();
-	ssize_t nbytes = smbc_read(fd, ptr, read_size);
-	smbclient_mutex.unlock();
+	ssize_t nbytes;
+
+	{
+		const ScopeUnlock unlock(mutex);
+		const std::lock_guard<Mutex> lock(smbclient_mutex);
+		nbytes = smbc_read(fd, ptr, read_size);
+	}
+
 	if (nbytes < 0)
 		throw MakeErrno("smbc_read() failed");
 
@@ -138,9 +143,14 @@ SmbclientInputStream::Read(void *ptr, size_t read_size)
 void
 SmbclientInputStream::Seek(offset_type new_offset)
 {
-	smbclient_mutex.lock();
-	off_t result = smbc_lseek(fd, new_offset, SEEK_SET);
-	smbclient_mutex.unlock();
+	off_t result;
+
+	{
+		const ScopeUnlock unlock(mutex);
+		const std::lock_guard<Mutex> lock(smbclient_mutex);
+		result = smbc_lseek(fd, new_offset, SEEK_SET);
+	}
+
 	if (result < 0)
 		throw MakeErrno("smbc_lseek() failed");
 
diff --git a/src/output/plugins/httpd/HttpdOutputPlugin.cxx b/src/output/plugins/httpd/HttpdOutputPlugin.cxx
index 731a5053a..89c306560 100644
--- a/src/output/plugins/httpd/HttpdOutputPlugin.cxx
+++ b/src/output/plugins/httpd/HttpdOutputPlugin.cxx
@@ -387,6 +387,7 @@ HttpdOutput::SendTag(const Tag &tag)
 
 		try {
 			encoder->SendTag(tag);
+			encoder->Flush();
 		} catch (const std::runtime_error &) {
 			/* ignore */
 		}