OSS: define HAVE_OSS, and disable on Linux by default

In many cases, OSS was used when the builder forgot to install the
alsa-lib development headers. This should not be an issue anymore, as
ALSA is now required on Linux by default.

I believe the fallback to OSS from ALSA and PulseAudio is causing more
confusion than it solves problem. Besides, the OSS emulation by ALSA
cannot mix, so OSS is almost completely useless on Linux, unless OSSv4
was specifically installed.

Moreover, Linux distributions have started dropping OSS completely.

NEWS

@@ -8,7 +8,9 @@ Important changes for packagers:
    Non-UTF-8 file systems support will be removed in future versions.
  * The VLC plugins path can be overriden with the VLC_PLUGIN_PATH environment
    variable. The --plugin-path command line option was removed.
- * The default tarballs are now .tar.xz
+ * The default tarballs are now compressed with XZ/LZMA: .tar.xz
+ * OSS support is not compiled on Linux by default, pass --enable-oss to the
+   configure script if you use OSSv4 or really want to use OSS emulation.
 
  * The NPAPI webplugin has moved to git://git.videolan.org/npapi-vlc.git
  * The ActiveX webplugin has moved to git://git.videolan.org/activex-vlc.git

configure.ac

@@ -3460,22 +3460,6 @@ dnl
 
 EXTEND_HELP_STRING([Audio plugins:])
 
-dnl
-dnl  OSS /dev/dsp module (enabled by default except on win32)
-dnl
-AC_ARG_ENABLE(oss,
-  [  --enable-oss            Open Sound System OSS support (default enabled)])
-
-if test "${enable_oss}" != "no" &&
-  (test "${SYS}" != "mingw32" -a "${SYS}" != "mingwce" ||
-   test "${enable_oss}" = "yes")
-then
-  AC_CHECK_HEADERS([soundcard.h sys/soundcard.h], [
-    VLC_ADD_PLUGIN([oss access_oss])
-    AC_CHECK_LIB(ossaudio,main,[VLC_ADD_LIBS([oss access_oss],[-lossaudio])])
-  ])
-fi
-
 dnl
 dnl  Pulseaudio module
 dnl
@@ -3516,6 +3500,29 @@ AS_IF([test "${enable_alsa}" != "no"], [
 ])
 AM_CONDITIONAL([HAVE_ALSA], [test "${have_alsa}" = "yes"])
 
+dnl
+dnl  Open Sound System module
+dnl
+AC_ARG_ENABLE(oss,
+  [AS_HELP_STRING([--enable-oss],
+    [support the Open Sound System OSS (default enabled on BSD)])],, [
+  AS_IF([test "$SYS" = "mingw32" -o "$SYS" = "mingwce" -o "$SYS" = "linux"], [
+    enable_oss="no"
+  ])
+])
+have_oss="no"
+OSS_LIBS=""
+AS_IF([test "$enable_oss" != "no"], [
+  AC_CHECK_HEADERS([soundcard.h sys/soundcard.h], [
+    have_oss="yes"
+    AC_CHECK_LIB(ossaudio, main, [
+      OSS_LIBS="-lossaudio"
+    ])
+  ])
+])
+AC_SUBST(OSS_LIBS)
+AM_CONDITIONAL([HAVE_OSS], [test "${have_oss}" = "yes"])
+
 dnl
 dnl  Portaudio module
 dnl

modules/access/Modules.am

@@ -54,7 +54,6 @@ SOURCES_cdda = \
         vcd/cdrom_internals.h \
         $(NULL)
 SOURCES_access_jack = jack.c
-SOURCES_access_oss = oss.c
 SOURCES_access_mtp = mtp.c
 SOURCES_access_sftp = sftp.c
 SOURCES_access_imem = imem.c
@@ -93,6 +92,13 @@ libvlc_LTLIBRARIES += \
 	libaccess_vdr_plugin.la \
 	$(NULL)
 
+libaccess_oss_plugin_la = oss.c
+libaccess_oss_plugin_la_LIBADD = $(AM_LIBADD) $(OSS_LIBS)
+libaccess_oss_plugin_la_DEPENDENCIES =
+if HAVE_OSS
+libvlc_LTLIBRARIES += libaccess_oss_plugin.la
+endif
+
 libaccess_alsa_plugin_la_SOURCES = alsa.c
 libaccess_alsa_plugin_la_CFLAGS = $(AM_CFLAGS) $(ALSA_CFLAGS)
 libaccess_alsa_plugin_la_LIBADD = $(AM_LIBADD) $(ALSA_LIBS)

modules/audio_output/Modules.am

 SOURCES_aout_directx = directx.c windows_audio_common.h
 SOURCES_aout_file = file.c
-SOURCES_oss = oss.c
 SOURCES_aout_sdl = sdl.c
 SOURCES_waveout = waveout.c windows_audio_common.h
 SOURCES_portaudio = portaudio.c
@@ -10,6 +9,13 @@ SOURCES_audioqueue = audioqueue.c
 
 libvlc_LTLIBRARIES += libaout_file_plugin.la
 
+liboss_plugin_la = oss.c
+liboss_plugin_la_LIBADD = $(AM_LIBADD) $(OSS_LIBS)
+liboss_plugin_la_DEPENDENCIES =
+if HAVE_OSS
+libvlc_LTLIBRARIES += liboss_plugin.la
+endif
+
 libalsa_plugin_la_SOURCES = alsa.c
 libalsa_plugin_la_CFLAGS = $(AM_CFLAGS) $(ALSA_CFLAGS)
 libalsa_plugin_la_LIBADD = $(AM_LIBADD) $(ALSA_LIBS)