encoder/twolame: new encoder plugin based on libtwolame

This encoder plugin is a replacement for the LAME encoder plugin for
those who prefer a "free" (non-patent encumbered) encoder library.
Most of the plugin source code is copied from the LAME encoder plugin,
since the LAME and TwoLAME APIs are nearly the same.

Makefile.am

@@ -432,10 +432,12 @@ endif
 
 ENCODER_CFLAGS = \
 	$(LAME_CFLAGS) \
+	$(TWOLAME_CFLAGS) \
 	$(VORBISENC_CFLAGS)
 
 ENCODER_LIBS = \
 	$(LAME_LIBS) \
+	$(TWOLAME_LIBS) \
 	$(VORBISENC_LIBS)
 
 ENCODER_SRC =
@@ -450,6 +452,10 @@ endif
 if ENABLE_LAME_ENCODER
 ENCODER_SRC += src/encoder/lame_encoder.c
 endif
+
+if ENABLE_TWOLAME_ENCODER
+ENCODER_SRC += src/encoder/twolame_encoder.c
+endif
 endif
 
 

NEWS

@@ -10,6 +10,8 @@ ver 0.16 (20??/??/??)
   - ffmpeg: support multiple tags
   - sndfile: new decoder plugin based on libsndfile
   - flac: load external cue sheet when no internal one
+* encoders:
+  - twolame: new encoder plugin based on libtwolame
 * mixers:
   - removed support for legacy mixer configuration
   - reimplemented software volume as mixer+filter plugin

configure.ac

@@ -618,6 +618,11 @@ AC_ARG_ENABLE(lame-encoder,
 		[enable the LAME mp3 encoder]),,
 	enable_lame_encoder=auto)
 
+AC_ARG_ENABLE(twolame-encoder,
+	AS_HELP_STRING([--enable-twolame-encoder],
+		[enable the TwoLAME mp2 encoder]),,
+	enable_twolame_encoder=auto)
+
 
 dnl
 dnl audio output plugins
@@ -1002,6 +1007,7 @@ else
 	# don't bother to check for encoder plugins
 	enable_vorbis_encoder=no
 	enable_lame_encoder=no
+	enable_twolame_encoder=no
 fi
 
 MPD_AUTO_PKG(vorbis_encoder, VORBISENC, [vorbisenc],
@@ -1016,8 +1022,12 @@ fi
 AC_SUBST(LAME_CFLAGS)
 AC_SUBST(LAME_LIBS)
 
+MPD_AUTO_PKG(twolame_encoder, TWOLAME, [twolame],
+	[TwoLAME encoder], [libtwolame not found])
+
 if test x$enable_vorbis_encoder != xno ||
-	test x$enable_lame_encoder != xno; then
+	test x$enable_lame_encoder != xno ||
+	test x$enable_twolame_encoder != xno; then
 	# at least one encoder plugin is enabled
 	enable_encoder=yes
 else
@@ -1076,6 +1086,12 @@ if test x$enable_lame_encoder = xyes; then
 		[Define to enable the lame encoder plugin])
 fi
 
+AM_CONDITIONAL(ENABLE_TWOLAME_ENCODER, test x$enable_twolame_encoder = xyes)
+if test x$enable_twolame_encoder = xyes; then
+	AC_DEFINE(ENABLE_TWOLAME_ENCODER, 1,
+		[Define to enable the TwoLAME encoder plugin])
+fi
+
 
 dnl
 dnl Documentation
@@ -1305,6 +1321,13 @@ if
 		else
 			echo " Ogg Vorbis encoder ............disabled"
 		fi
+
+		if test x$enable_twolame_encoder = xyes; then
+			echo " TwoLAME mp3 encoder ...........enabled"
+		else
+			echo " TwoLAME mp3 encoder ...........disabled"
+		fi
+
 		echo ""
 fi
 

src/encoder/twolame_encoder.c

@@ -0,0 +1,299 @@
+/*
+ * Copyright (C) 2003-2009 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 "encoder_api.h"
+#include "encoder_plugin.h"
+#include "audio_format.h"
+
+#include <twolame.h>
+#include <assert.h>
+#include <string.h>
+
+struct twolame_encoder {
+	struct encoder encoder;
+
+	struct audio_format audio_format;
+	float quality;
+	int bitrate;
+
+	twolame_options *options;
+
+	unsigned char buffer[32768];
+	size_t buffer_length;
+
+	/**
+	 * Call libtwolame's flush function when the buffer is empty?
+	 */
+	bool flush;
+};
+
+extern const struct encoder_plugin twolame_encoder_plugin;
+
+static inline GQuark
+twolame_encoder_quark(void)
+{
+	return g_quark_from_static_string("twolame_encoder");
+}
+
+static bool
+twolame_encoder_configure(struct twolame_encoder *encoder,
+			  const struct config_param *param, GError **error)
+{
+	const char *value;
+	char *endptr;
+
+	value = config_get_block_string(param, "quality", NULL);
+	if (value != NULL) {
+		/* a quality was configured (VBR) */
+
+		encoder->quality = g_ascii_strtod(value, &endptr);
+
+		if (*endptr != '\0' || encoder->quality < -1.0 ||
+		    encoder->quality > 10.0) {
+			g_set_error(error, twolame_encoder_quark(), 0,
+				    "quality \"%s\" is not a number in the "
+				    "range -1 to 10, line %i",
+				    value, param->line);
+			return false;
+		}
+
+		if (config_get_block_string(param, "bitrate", NULL) != NULL) {
+			g_set_error(error, twolame_encoder_quark(), 0,
+				    "quality and bitrate are "
+				    "both defined (line %i)",
+				    param->line);
+			return false;
+		}
+	} else {
+		/* a bit rate was configured */
+
+		value = config_get_block_string(param, "bitrate", NULL);
+		if (value == NULL) {
+			g_set_error(error, twolame_encoder_quark(), 0,
+				    "neither bitrate nor quality defined "
+				    "at line %i",
+				    param->line);
+			return false;
+		}
+
+		encoder->quality = -2.0;
+		encoder->bitrate = g_ascii_strtoll(value, &endptr, 10);
+
+		if (*endptr != '\0' || encoder->bitrate <= 0) {
+			g_set_error(error, twolame_encoder_quark(), 0,
+				    "bitrate at line %i should be a positive integer",
+				    param->line);
+			return false;
+		}
+	}
+
+	return true;
+}
+
+static struct encoder *
+twolame_encoder_init(const struct config_param *param, GError **error)
+{
+	struct twolame_encoder *encoder;
+
+	g_debug("libtwolame version %s", get_twolame_version());
+
+	encoder = g_new(struct twolame_encoder, 1);
+	encoder_struct_init(&encoder->encoder, &twolame_encoder_plugin);
+
+	/* load configuration from "param" */
+	if (!twolame_encoder_configure(encoder, param, error)) {
+		/* configuration has failed, roll back and return error */
+		g_free(encoder);
+		return NULL;
+	}
+
+	return &encoder->encoder;
+}
+
+static void
+twolame_encoder_finish(struct encoder *_encoder)
+{
+	struct twolame_encoder *encoder = (struct twolame_encoder *)_encoder;
+
+	/* the real libtwolame cleanup was already performed by
+	   twolame_encoder_close(), so no real work here */
+	g_free(encoder);
+}
+
+static bool
+twolame_encoder_setup(struct twolame_encoder *encoder, GError **error)
+{
+	if (encoder->quality >= -1.0) {
+		/* a quality was configured (VBR) */
+
+		if (0 != twolame_set_VBR(encoder->options, true)) {
+			g_set_error(error, twolame_encoder_quark(), 0,
+				    "error setting twolame VBR mode");
+			return false;
+		}
+		if (0 != twolame_set_VBR_q(encoder->options, encoder->quality)) {
+			g_set_error(error, twolame_encoder_quark(), 0,
+				    "error setting twolame VBR quality");
+			return false;
+		}
+	} else {
+		/* a bit rate was configured */
+
+		if (0 != twolame_set_brate(encoder->options, encoder->bitrate)) {
+			g_set_error(error, twolame_encoder_quark(), 0,
+				    "error setting twolame bitrate");
+			return false;
+		}
+	}
+
+	if (0 != twolame_set_num_channels(encoder->options,
+					  encoder->audio_format.channels)) {
+		g_set_error(error, twolame_encoder_quark(), 0,
+			    "error setting twolame num channels");
+		return false;
+	}
+
+	if (0 != twolame_set_in_samplerate(encoder->options,
+					   encoder->audio_format.sample_rate)) {
+		g_set_error(error, twolame_encoder_quark(), 0,
+			    "error setting twolame sample rate");
+		return false;
+	}
+
+	if (0 > twolame_init_params(encoder->options)) {
+		g_set_error(error, twolame_encoder_quark(), 0,
+			    "error initializing twolame params");
+		return false;
+	}
+
+	return true;
+}
+
+static bool
+twolame_encoder_open(struct encoder *_encoder, struct audio_format *audio_format,
+		     GError **error)
+{
+	struct twolame_encoder *encoder = (struct twolame_encoder *)_encoder;
+
+	audio_format->bits = 16;
+	audio_format->channels = 2;
+
+	encoder->audio_format = *audio_format;
+
+	encoder->options = twolame_init();
+	if (encoder->options == NULL) {
+		g_set_error(error, twolame_encoder_quark(), 0,
+			    "twolame_init() failed");
+		return false;
+	}
+
+	if (!twolame_encoder_setup(encoder, error)) {
+		twolame_close(&encoder->options);
+		return false;
+	}
+
+	encoder->buffer_length = 0;
+	encoder->flush = false;
+
+	return true;
+}
+
+static void
+twolame_encoder_close(struct encoder *_encoder)
+{
+	struct twolame_encoder *encoder = (struct twolame_encoder *)_encoder;
+
+	twolame_close(&encoder->options);
+}
+
+static bool
+twolame_encoder_flush(struct encoder *_encoder, G_GNUC_UNUSED GError **error)
+{
+	struct twolame_encoder *encoder = (struct twolame_encoder *)_encoder;
+
+	encoder->flush = true;
+	return true;
+}
+
+static bool
+twolame_encoder_write(struct encoder *_encoder,
+		      const void *data, size_t length,
+		      G_GNUC_UNUSED GError **error)
+{
+	struct twolame_encoder *encoder = (struct twolame_encoder *)_encoder;
+	unsigned num_frames;
+	const int16_t *src = (const int16_t*)data;
+	int bytes_out;
+
+	assert(encoder->buffer_length == 0);
+
+	num_frames =
+		length / audio_format_frame_size(&encoder->audio_format);
+
+	bytes_out = twolame_encode_buffer_interleaved(encoder->options,
+						      src, num_frames,
+						      encoder->buffer,
+						      sizeof(encoder->buffer));
+	if (bytes_out < 0) {
+		g_set_error(error, twolame_encoder_quark(), 0,
+			    "twolame encoder failed");
+		return false;
+	}
+
+	encoder->buffer_length = (size_t)bytes_out;
+	return true;
+}
+
+static size_t
+twolame_encoder_read(struct encoder *_encoder, void *dest, size_t length)
+{
+	struct twolame_encoder *encoder = (struct twolame_encoder *)_encoder;
+
+	if (encoder->buffer_length == 0 && encoder->flush) {
+		int ret = twolame_encode_flush(encoder->options,
+					       encoder->buffer,
+					       sizeof(encoder->buffer));
+		if (ret > 0)
+			encoder->buffer_length = (size_t)ret;
+
+		encoder->flush = false;
+	}
+
+	if (length > encoder->buffer_length)
+		length = encoder->buffer_length;
+
+	memcpy(dest, encoder->buffer, length);
+
+	encoder->buffer_length -= length;
+	memmove(encoder->buffer, encoder->buffer + length,
+		encoder->buffer_length);
+
+	return length;
+}
+
+const struct encoder_plugin twolame_encoder_plugin = {
+	.name = "twolame",
+	.init = twolame_encoder_init,
+	.finish = twolame_encoder_finish,
+	.open = twolame_encoder_open,
+	.close = twolame_encoder_close,
+	.flush = twolame_encoder_flush,
+	.write = twolame_encoder_write,
+	.read = twolame_encoder_read,
+};

src/encoder_list.c

@@ -25,6 +25,7 @@
 
 extern const struct encoder_plugin vorbis_encoder_plugin;
 extern const struct encoder_plugin lame_encoder_plugin;
+extern const struct encoder_plugin twolame_encoder_plugin;
 
 static const struct encoder_plugin *encoder_plugins[] = {
 #ifdef ENABLE_VORBIS_ENCODER
@@ -32,6 +33,9 @@ static const struct encoder_plugin *encoder_plugins[] = {
 #endif
 #ifdef ENABLE_LAME_ENCODER
 	&lame_encoder_plugin,
+#endif
+#ifdef ENABLE_TWOLAME_ENCODER
+	&twolame_encoder_plugin,
 #endif
 	NULL
 };