Add Opus encoding support

.github/workflows/build-and-test.yaml

@@ -31,6 +31,7 @@ jobs:
           libogg-dev \
           libpipewire-0.3-dev \
           libsndfile1-dev \
+          libopusenc-dev \
           libvorbis-dev \
           portaudio19-dev
     - uses: actions/checkout@v5
@@ -49,6 +50,7 @@ jobs:
         ${{ matrix.audio-backend }}
         -DENABLE_MP3LAME=ON
         -DENABLE_SNDFILE=ON
+        -DENABLE_OPUS=ON
         -DENABLE_VORBIS=ON
     - name: Build
       working-directory: ${{ github.workspace }}/build

.github/workflows/code-scanning.yaml

@@ -32,11 +32,12 @@ jobs:
           libogg-dev \
           libpipewire-0.3-dev \
           libsndfile1-dev \
+          libopusenc-dev \
           libvorbis-dev \
           portaudio19-dev
     - uses: actions/checkout@v5
     - name: Initialize CodeQL
-      uses: github/codeql-action/init@v3
+      uses: github/codeql-action/init@v4
       with:
         languages: cpp
         queries: security-and-quality
@@ -56,9 +57,10 @@ jobs:
         -DENABLE_PORTAUDIO=ON
         -DENABLE_MP3LAME=ON
         -DENABLE_SNDFILE=ON
+        -DENABLE_OPUS=ON
         -DENABLE_VORBIS=ON
     - name: Build
       working-directory: ${{ github.workspace }}/build
       run: cmake --build . --config ${{ matrix.build-type }}
     - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@v3
+      uses: github/codeql-action/analyze@v4

CMakeLists.txt

@@ -5,7 +5,7 @@
 cmake_minimum_required(VERSION 3.11)
 
 project(svar
-	VERSION 2.0.0
+	VERSION 2.1.0
 	DESCRIPTION "Simple Voice Activated Recorder"
 	LANGUAGES C)
 
@@ -27,7 +27,8 @@ endif()
 
 option(ENABLE_MP3LAME "Enable MP3 support.")
 option(ENABLE_SNDFILE "Enable WAV support.")
-option(ENABLE_VORBIS "Enable OGG support.")
+option(ENABLE_OPUS "Enable OPUS support.")
+option(ENABLE_VORBIS "Enable VORBIS support.")
 
 configure_file(
 	${PROJECT_SOURCE_DIR}/config.h.in
@@ -77,10 +78,16 @@ if(ENABLE_MP3LAME)
 	target_link_libraries(svarcore Mp3Lame::Mp3Lame)
 endif()
 
+if(ENABLE_OPUS)
+	pkg_check_modules(OggOpus REQUIRED IMPORTED_TARGET libopusenc)
+	target_sources(svarcore PRIVATE src/writer-opus.c)
+	target_link_libraries(svarcore PkgConfig::OggOpus)
+endif()
+
 if(ENABLE_VORBIS)
-	pkg_check_modules(VorbisOgg REQUIRED IMPORTED_TARGET vorbis vorbisenc ogg)
-	target_sources(svarcore PRIVATE src/writer-ogg.c)
-	target_link_libraries(svarcore PkgConfig::VorbisOgg)
+	pkg_check_modules(OggVorbis REQUIRED IMPORTED_TARGET vorbis vorbisenc ogg)
+	target_sources(svarcore PRIVATE src/writer-vorbis.c)
+	target_link_libraries(svarcore PkgConfig::OggVorbis)
 endif()
 
 if(BUILD_TESTING)

README.md

@@ -18,7 +18,8 @@ Supported output formats:
 - RAW (PCM 16bit interleaved)
 - WAV, RF64 ([libsndfile](http://www.mega-nerd.com/libsndfile/))
 - MP3 ([mp3lame](http://lame.sourceforge.net/))
-- OGG ([libvorbis](http://www.xiph.org/vorbis/))
+- OGG/OPUS ([libopusenc](https://opus-codec.org/))
+- OGG/VORBIS ([libvorbis](http://www.xiph.org/vorbis/))
 
 For low CPU consumption WAV is recommended - it is the default selection.
 
@@ -39,6 +40,6 @@ from the last 100 ms of captured audio.
 mkdir build && cd build
 cmake .. \
   -DENABLE_ALSA=ON -DENABLE_PIPEWIRE=ON -DENABLE_PORTAUDIO=ON \
-  -DENABLE_SNDFILE=ON -DENABLE_MP3LAME=ON -DENABLE_VORBIS=ON
+  -DENABLE_SNDFILE=ON -DENABLE_MP3LAME=ON -DENABLE_OPUS=ON -DENABLE_VORBIS=ON
 make && make install
 ```

config.h.in

@@ -25,6 +25,9 @@
 /* Define to 1 if SNDFile is enabled. */
 #cmakedefine ENABLE_SNDFILE 1
 
+/* Define to 1 if Ogg Opus is enabled. */
+#cmakedefine ENABLE_OPUS 1
+
 /* Define to 1 if Ogg Vorbis is enabled. */
 #cmakedefine ENABLE_VORBIS 1
 

src/main.c

@@ -39,8 +39,11 @@
 #if ENABLE_SNDFILE
 # include "writer-wav.h"
 #endif
+#if ENABLE_OPUS
+# include "writer-opus.h"
+#endif
 #if ENABLE_VORBIS
-# include "writer-ogg.h"
+# include "writer-vorbis.h"
 #endif
 
 /* Application banner used for output file comment string. */
@@ -97,8 +100,13 @@ static void print_audio_info(void) {
 			printf("Output bit rate [kbit/s]: min=%d max=%d\n",
 					bitrate_min / 1000, bitrate_max / 1000);
 #endif
+#if ENABLE_OPUS
+		if (writer->type == WRITER_TYPE_OPUS)
+			printf("Output bit rate [kbit/s]: %d\n",
+					bitrate_nom / 1000);
+#endif
 #if ENABLE_VORBIS
-		if (writer->type == WRITER_TYPE_OGG)
+		if (writer->type == WRITER_TYPE_VORBIS)
 			printf("Output bit rate [kbit/s]: min=%d nominal=%d max=%d\n",
 					bitrate_min / 1000, bitrate_nom / 1000, bitrate_max / 1000);
 #endif
@@ -142,8 +150,10 @@ int main(int argc, char *argv[]) {
 	/* Select default output format based on available libraries. */
 #if ENABLE_SNDFILE
 	enum writer_type writer_type = WRITER_TYPE_WAV;
+#elif ENABLE_OPUS
+	enum writer_type writer_type = WRITER_TYPE_OPUS;
 #elif ENABLE_VORBIS
-	enum writer_type writer_type = WRITER_TYPE_OGG;
+	enum writer_type writer_type = WRITER_TYPE_VORBIS;
 #elif ENABLE_MP3LAME
 	enum writer_type writer_type = WRITER_TYPE_MP3;
 #else
@@ -250,8 +260,11 @@ int main(int argc, char *argv[]) {
 				WRITER_TYPE_WAV,
 				WRITER_TYPE_RF64,
 #endif
+#if ENABLE_OPUS
+				WRITER_TYPE_OPUS,
+#endif
 #if ENABLE_VORBIS
-				WRITER_TYPE_OGG,
+				WRITER_TYPE_VORBIS,
 #endif
 			};
 
@@ -379,9 +392,15 @@ int main(int argc, char *argv[]) {
 			writer_mp3_print_internals(writer);
 		break;
 #endif
+#if ENABLE_OPUS
+	case WRITER_TYPE_OPUS:
+		writer = writer_opus_new(pcm_format, pcm_channels, pcm_rate,
+				bitrate_nom, banner);
+		break;
+#endif
 #if ENABLE_VORBIS
-	case WRITER_TYPE_OGG:
-		writer = writer_ogg_new(pcm_format, pcm_channels, pcm_rate,
+	case WRITER_TYPE_VORBIS:
+		writer = writer_vorbis_new(pcm_format, pcm_channels, pcm_rate,
 				bitrate_min, bitrate_nom, bitrate_max, banner);
 		break;
 #endif

src/writer-mp3.c

@@ -77,7 +77,7 @@ struct writer * writer_mp3_new(
 		int bitrate_min, int bitrate_max, const char * comment) {
 
 	if (format != PCM_FORMAT_S16LE) {
-		error("MP3 unsupported PCM format: %s", pcm_format_name(format));
+		error("LAME: Unsupported PCM format: %s", pcm_format_name(format));
 		return NULL;
 	}
 

src/writer-opus.c

@@ -0,0 +1,127 @@
+/*
+ * SVAR - writer-opus.c
+ * SPDX-FileCopyrightText: 2025 Arkadiusz Bokowy and contributors
+ * SPDX-License-Identifier: MIT
+ */
+
+#include "writer-opus.h"
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <opusenc.h>
+
+#include "log.h"
+#include "pcm.h"
+#include "writer.h"
+
+struct writer_opus {
+	OggOpusEnc * enc;
+	OggOpusComments * comments;
+	unsigned int channels;
+	unsigned int sampling;
+	int bitrate;
+};
+
+static int writer_opus_open(struct writer * writer, const char * pathname) {
+	struct writer_opus * w = writer->w;
+
+	writer->close(writer);
+
+	int err;
+	const int family = w->channels <= 2 ? 0 : 1;
+	if ((w->enc = ope_encoder_create_file(pathname, w->comments, w->sampling,
+				w->channels, family, &err)) == NULL) {
+		error("OPUS: Couldn't create encoder: %s", ope_strerror(err));
+		errno = EINVAL;
+		return -1;
+	}
+
+	if ((err = ope_encoder_ctl(w->enc, OPUS_SET_BITRATE(w->bitrate))) != OPE_OK)
+		warn("OPUS: Couldn't set bitrate: %s", ope_strerror(err));
+
+	writer->opened = true;
+	return 0;
+}
+
+static void writer_opus_close(struct writer * writer) {
+	struct writer_opus * w = writer->w;
+	writer->opened = false;
+
+	if (w->enc == NULL)
+		return;
+
+	ope_encoder_drain(w->enc);
+	ope_encoder_destroy(w->enc);
+	w->enc = NULL;
+}
+
+static ssize_t writer_opus_write(struct writer * writer, const void * buffer, size_t frames) {
+	struct writer_opus * w = writer->w;
+
+	int err;
+	/* Write 16-bit PCM samples to the encoder. */
+	if ((err = ope_encoder_write(w->enc, (const opus_int16 *)buffer, frames)) != OPE_OK) {
+		error("OPUS: Encoding error: %s", ope_strerror(err));
+		return -1;
+	}
+
+	return frames;
+}
+
+static void writer_opus_free(struct writer * writer) {
+	if (writer == NULL)
+		return;
+	struct writer_opus * w = writer->w;
+	writer->close(writer);
+	if (w->comments != NULL)
+		ope_comments_destroy(w->comments);
+	free(writer->w);
+	free(writer);
+}
+
+struct writer * writer_opus_new(
+		enum pcm_format format, unsigned int channels, unsigned int sampling,
+		int bitrate, const char * comment) {
+
+	if (format != PCM_FORMAT_S16LE) {
+		error("OPUS: Unsupported PCM format: %s", pcm_format_name(format));
+		return NULL;
+	}
+
+	struct writer * writer;
+	if ((writer = malloc(sizeof(*writer))) == NULL)
+		return NULL;
+
+	writer->type = WRITER_TYPE_OPUS;
+	writer->opened = false;
+	writer->open = writer_opus_open;
+	writer->write = writer_opus_write;
+	writer->close = writer_opus_close;
+	writer->free = writer_opus_free;
+
+	struct writer_opus * w;
+	if ((writer->w = w = calloc(1, sizeof(*w))) == NULL) {
+		free(writer);
+		return NULL;
+	}
+
+	if ((w->comments = ope_comments_create()) == NULL) {
+		writer_opus_free(writer);
+		return NULL;
+	}
+
+	w->channels = channels;
+	w->sampling = sampling;
+	w->bitrate = bitrate;
+
+	if (comment != NULL) {
+		char tag[8 + strlen(comment) + 1];
+		snprintf(tag, sizeof(tag), "ENCODER=%s", comment);
+		ope_comments_add_string(w->comments, tag);
+	}
+
+	return writer;
+}

src/writer-opus.h

@@ -0,0 +1,18 @@
+/*
+ * SVAR - writer-opus.h
+ * SPDX-FileCopyrightText: 2025 Arkadiusz Bokowy and contributors
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+#ifndef SVAR_WRITER_OPUS_H_
+#define SVAR_WRITER_OPUS_H_
+
+#include "pcm.h"
+#include "writer.h"
+
+struct writer * writer_opus_new(
+		enum pcm_format format, unsigned int channels, unsigned int sampling,
+		int bitrate, const char * comment);
+
+#endif