Add support for ALSA compressed offload

See
https://docs.kernel.org/sound/designs/compress-offload.html
https://github.com/alsa-project/tinycompress

meson.build

@@ -266,6 +266,15 @@ if not readline_dep.found()
   readline_dep = cc.find_library('readline', required : get_option('readline'))
 endif
 
+need_avcodec = get_option('ffmpeg').enabled() or get_option('pw-cat').enabled()
+avcodec_dep = dependency('libavcodec', required: need_avcodec)
+avformat_dep = dependency('libavformat', required: get_option('pw-cat'))
+summary({'Libav for pw-cat': avcodec_dep.found() and avformat_dep.found()}, bool_yn: true, section: 'Support for ALSA Compress-Offload API')
+tinycompress_dep = cc.find_library('tinycompress', has_headers: ['tinycompress/tinycompress.h' ], required: get_option('compressed-offload'))
+summary({'Compressed offload sink': tinycompress_dep.found()}, bool_yn: true, section: 'Support for ALSA Compress-Offload API')
+compressed_offload_enabled = avcodec_dep.found() and avformat_dep.found() and tinycompress_dep.found()
+cdata.set('HAVE_COMPRESSED_OFFLOAD', compressed_offload_enabled)
+
 summary({'readline (for pw-cli)': readline_dep.found()}, bool_yn: true, section: 'Misc dependencies')
 cdata.set('HAVE_READLINE', readline_dep.found())
 ncurses_dep = dependency('ncursesw', required : false)

meson_options.txt

@@ -273,3 +273,7 @@ option('gsettings',
        description: 'Enable code that depends on gsettings',
        type: 'feature',
        value: 'auto')
+option('compressed-offload',
+       description: 'Enable compressed offload support',
+       type: 'feature',
+       value: 'auto')

spa/include/spa/param/audio/compressed.h

@@ -0,0 +1,39 @@
+/* Simple Plugin API
+ *
+ * Copyright © 2021 Wim Taymans
+ *           © 2022 Asymptotic Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef SPA_AUDIO_COMPRESSED_H
+#define SPA_AUDIO_COMPRESSED_H
+
+#include <spa/param/audio/aac.h>
+#include <spa/param/audio/alac.h>
+#include <spa/param/audio/amr.h>
+#include <spa/param/audio/ape.h>
+#include <spa/param/audio/flac.h>
+#include <spa/param/audio/mp3.h>
+#include <spa/param/audio/ra.h>
+#include <spa/param/audio/vorbis.h>
+#include <spa/param/audio/wma.h>
+
+#endif /* SPA_AUDIO_COMPRESSED_H */

spa/meson.build

@@ -74,7 +74,6 @@ if get_option('spa-plugins').allowed()
       summary({'ModemManager': mm_dep.found()}, bool_yn: true, section: 'Bluetooth backends')
     endif
   endif
-  avcodec_dep = dependency('libavcodec', required: get_option('ffmpeg'))
   jack_dep = dependency('jack', version : '>= 1.9.10', required: get_option('jack'))
   summary({'JACK2': jack_dep.found()}, bool_yn: true, section: 'Backend')
   vulkan_dep = dependency('vulkan', disabler : true, version : '>= 1.1.69', required: get_option('vulkan'))

spa/plugins/alsa/alsa.c

@@ -22,6 +22,8 @@
  * DEALINGS IN THE SOFTWARE.
  */
 
+#include "config.h"
+
 #include <errno.h>
 
 #include <spa/support/plugin.h>
@@ -33,6 +35,9 @@ extern const struct spa_handle_factory spa_alsa_udev_factory;
 extern const struct spa_handle_factory spa_alsa_device_factory;
 extern const struct spa_handle_factory spa_alsa_seq_bridge_factory;
 extern const struct spa_handle_factory spa_alsa_acp_device_factory;
+#ifdef HAVE_COMPRESSED_OFFLOAD
+extern const struct spa_handle_factory spa_alsa_compressed_sink_factory;
+#endif
 
 struct spa_log_topic log_topic = SPA_LOG_TOPIC(0, "spa.alsa");
 struct spa_log_topic *alsa_log_topic = &log_topic;
@@ -62,6 +67,11 @@ int spa_handle_factory_enum(const struct spa_handle_factory **factory, uint32_t
 	case 5:
 		*factory = &spa_alsa_acp_device_factory;
 		break;
+#ifdef HAVE_COMPRESSED_OFFLOAD
+	case 6:
+		*factory = &spa_alsa_compressed_sink_factory;
+		break;
+#endif
 	default:
 		return 0;
 	}

spa/plugins/alsa/meson.build

@@ -1,6 +1,8 @@
 subdir('acp')
 subdir('mixer')
 
+spa_alsa_dependencies = [ spa_dep, alsa_dep, libudev_dep, mathlib, epoll_shim_dep, libinotify_dep ]
+
 spa_alsa_sources = ['alsa.c',
                 'alsa.h',
                 'alsa-udev.c',
@@ -12,12 +14,17 @@ spa_alsa_sources = ['alsa.c',
                 'alsa-seq-bridge.c',
                 'alsa-seq.c']
 
+if tinycompress_dep.found()
+  spa_alsa_sources += [ 'alsa-compressed-sink.c' ]
+  spa_alsa_dependencies += tinycompress_dep
+endif
+
 spa_alsa = shared_library(
   'spa-alsa',
   [ spa_alsa_sources ],
   c_args : acp_c_args,
   include_directories : [configinc],
-  dependencies : [ spa_dep, alsa_dep, libudev_dep, mathlib, epoll_shim_dep, libinotify_dep ],
+  dependencies : spa_alsa_dependencies,
   link_with : [ acp_lib ],
   install : true,
   install_dir : spa_plugindir / 'alsa'