+/*****************************************************************************
+ * Probe: probe the audio device for available formats and channels
+ *****************************************************************************/
+static void Probe( aout_instance_t * p_aout )
+{
+ struct aout_sys_t * p_sys = p_aout->output.p_sys;
+ vlc_value_t val;
+ int i_format, i_nb_channels;
+
+ var_Create( p_aout, "audio-device", VLC_VAR_STRING | VLC_VAR_ISLIST );
+
+ if( ioctl( p_sys->i_fd, SNDCTL_DSP_RESET, NULL ) < 0 )
+ {
+ msg_Err( p_aout, "cannot reset OSS audio device" );
+ var_Destroy( p_aout, "audio-device" );
+ return;
+ }
+
+ if ( AOUT_FMT_NON_LINEAR( &p_aout->output.output ) )
+ {
+ i_format = AFMT_AC3;
+
+ if( ioctl( p_sys->i_fd, SNDCTL_DSP_SETFMT, &i_format ) >= 0
+ && i_format == AFMT_AC3 )
+ {
+ val.psz_string = N_("S/PDIF");
+ var_Change( p_aout, "audio-device", VLC_VAR_ADDCHOICE, &val );
+ }
+ }
+
+ /* Go to PCM mode. */
+ i_format = AFMT_S16_NE;
+ if( ioctl( p_sys->i_fd, SNDCTL_DSP_RESET, NULL ) < 0 ||
+ ioctl( p_sys->i_fd, SNDCTL_DSP_SETFMT, &i_format ) < 0 )
+ {
+ return;
+ }
+
+#ifdef SNDCTL_DSP_GETCHANNELMASK
+ if ( aout_FormatNbChannels( &p_aout->output.output ) > 2 )
+ {
+ /* Check that the device supports this. */
+
+ int i_chanmask;
+ if ( ioctl( p_sys->i_fd, SNDCTL_DSP_GETCHANNELMASK,
+ &i_chanmask ) == 0 )
+ {
+ if ( !(i_chanmask & DSP_BIND_FRONT) )
+ {
+ msg_Err( p_aout, "No front channels ! (%x)",
+ i_chanmask );
+ return;
+ }
+
+ if ( (i_chanmask & (DSP_BIND_SURR | DSP_BIND_CENTER_LFE))
+ && (p_aout->output.output.i_physical_channels ==
+ (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
+ | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT
+ | AOUT_CHAN_LFE)) )
+ {
+ val.psz_string = N_("5.1");
+ var_Change( p_aout, "audio-device", VLC_VAR_ADDCHOICE, &val );
+ }
+
+ if ( (i_chanmask & DSP_BIND_SURR)
+ && (p_aout->output.output.i_physical_channels &
+ (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
+ | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT)) )
+ {
+ val.psz_string = N_("2 Front 2 Rear");
+ var_Change( p_aout, "audio-device", VLC_VAR_ADDCHOICE, &val );
+ }
+ }
+ }
+#endif
+
+ /* Test for stereo. */
+ i_nb_channels = 2;
+ if( ioctl( p_sys->i_fd, SNDCTL_DSP_CHANNELS, &i_nb_channels ) >= 0
+ && i_nb_channels == 2 )
+ {
+ val.psz_string = N_("Stereo");
+ var_Change( p_aout, "audio-device", VLC_VAR_ADDCHOICE, &val );
+ }
+
+ /* Reset all. */
+ i_format = AFMT_S16_NE;
+ if( ioctl( p_sys->i_fd, SNDCTL_DSP_RESET, NULL ) < 0 ||
+ ioctl( p_sys->i_fd, SNDCTL_DSP_SETFMT, &i_format ) < 0 )
+ {
+ msg_Err( p_aout, "cannot reset OSS audio device" );
+ var_Destroy( p_aout, "audio-device" );
+ return;
+ }
+
+ /* Test for mono. */
+ i_nb_channels = 1;
+ if( ioctl( p_sys->i_fd, SNDCTL_DSP_CHANNELS, &i_nb_channels ) >= 0
+ && i_nb_channels == 1 )
+ {
+ val.psz_string = N_("Mono");
+ var_Change( p_aout, "audio-device", VLC_VAR_ADDCHOICE, &val );
+ }
+}
+