[vlc-devel] [PATCH 2/2] audiofilter: add softclip using Opus

[Tristan Matthews]

---
 NEWS                 |  1 +
 modules/MODULES_LIST |  2 +-
 modules/codec/opus.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/NEWS b/NEWS
index 9eae56c..e009d6c 100644
--- a/NEWS
+++ b/NEWS
@@ -148,6 +148,7 @@ Audio output:
  * Support EAC3 and TRUEHD pass-through for PulseAudio
 
 Audio filters:
+ * Add softclip filter using Opus
  * Add SoX Resampler library audio filter module (converter and resampler)
  * a52tospdif and dtstospdif audio converters are merged into tospdif,
    this new converter can convert AC3, DTS, EAC3 and TRUEHD to a IEC61937 frame
diff --git a/modules/MODULES_LIST b/modules/MODULES_LIST
index 04468e4..aa2e223 100644
--- a/modules/MODULES_LIST
+++ b/modules/MODULES_LIST
@@ -274,7 +274,7 @@ $Id$
  * opencv_example: OpenCV example (face identification)
  * opencv_wrapper: OpenCV wrapper video filter
  * opensles_android: OpenSL ES audio output for Android
- * opus: a opus audio decoder/packetizer/encoder using the libopus library
+ * opus: a opus audio decoder/packetizer/encoder/filter using the libopus library
  * os2drive: service discovery for OS/2 drives
  * oss: audio output module using the OSS /dev/dsp interface
  * osx_notifications: announce currently playing stream to OS X/Growl
diff --git a/modules/codec/opus.c b/modules/codec/opus.c
index a5953bc..7c2cdd1 100644
--- a/modules/codec/opus.c
+++ b/modules/codec/opus.c
@@ -33,6 +33,7 @@
 #include <vlc_input.h>
 #include <vlc_codec.h>
 #include <vlc_aout.h>
+#include <vlc_filter.h>
 #include "../demux/xiph.h"
 
 #include <ogg/ogg.h>
@@ -54,6 +55,8 @@ static void CloseDecoder  ( vlc_object_t * );
 static int  OpenEncoder   ( vlc_object_t * );
 static void CloseEncoder  ( vlc_object_t * );
 #endif
+static int  OpenFilter ( vlc_object_t * );
+static void CloseFilter ( vlc_object_t * );
 
 vlc_module_begin ()
     set_category( CAT_INPUT )
@@ -72,8 +75,16 @@ vlc_module_begin ()
     set_callbacks( OpenEncoder, CloseEncoder )
 #endif
 
+    add_submodule ()
+    set_shortname( N_("Softclip") )
+    set_description( N_("Opus softclip") )
+    set_capability( "audio filter", 50 )
+    set_callbacks( OpenFilter, CloseFilter )
+
 vlc_module_end ()
 
+static block_t *ApplyFilter (filter_t *, block_t *);
+
 /*****************************************************************************
  * decoder_sys_t : opus decoder descriptor
  *****************************************************************************/
@@ -743,3 +754,36 @@ static void CloseEncoder(vlc_object_t *p_this)
     free(sys);
 }
 #endif /* ENABLE_SOUT */
+
+static int OpenFilter (vlc_object_t *obj)
+{
+    filter_t *filter = (filter_t *)obj;
+
+    filter->fmt_out.audio.i_format = filter->fmt_in.audio.i_format = VLC_CODEC_FL32;
+    /* Cannot remix */
+    if (filter->fmt_in.audio.i_physical_channels != filter->fmt_out.audio.i_physical_channels
+     || filter->fmt_in.audio.i_original_channels != filter->fmt_out.audio.i_original_channels)
+        return VLC_EGENERIC;
+
+    filter->pf_audio_filter = ApplyFilter;
+    filter->p_sys = calloc( AOUT_CHAN_MAX, sizeof( float ) );
+    if( unlikely( filter->p_sys == NULL ) )
+        return VLC_ENOMEM;
+
+    return VLC_SUCCESS;
+}
+
+static block_t *ApplyFilter (filter_t *filter, block_t *block)
+{
+    float *p_softclip_state = (float *)filter->p_sys;
+    int channels = aout_FormatNbChannels(&filter->fmt_in.audio);
+    opus_pcm_soft_clip((float *)block->p_buffer, block->i_nb_samples, channels,
+        p_softclip_state);
+    return block;
+}
+
+static void CloseFilter (vlc_object_t *obj)
+{
+    filter_t *filter = (filter_t *)obj;
+    free(filter->p_sys);
+}
-- 
2.7.4