DSP plugin interface, weeee :D

audio/ext/ssnes_dsp.h

@@ -0,0 +1,97 @@
+/////
+// API header for external SSNES DSP plugins.
+//
+//
+
+#ifndef __SSNES_DSP_PLUGIN_H
+#define __SSNES_DSP_PLUGIN_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef _WIN32
+#ifdef SSNES_DLL_IMPORT
+#define SSNES_API_EXPORT __declspec(dllimport) 
+#else
+#define SSNES_API_EXPORT __declspec(dllexport) 
+#endif
+#define SSNES_API_CALLTYPE __cdecl
+#else
+#define SSNES_API_EXPORT
+#define SSNES_API_CALLTYPE
+#endif
+
+#define SSNES_FALSE 0
+#define SSNES_TRUE 1
+
+typedef struct ssnes_dsp_info
+{
+   // Input sample rate that the DSP plugin receives. This is generally ~32kHz.
+   // Some small variance is allowed due to syncing behavior.
+   float input_rate;
+   // SSNES requests that the DSP plugin resamples the 
+   // input to a certain frequency.
+   //
+   // However, the plugin might ignore this
+   // using the resample field in ssnes_dsp_output_t (see below).
+   float output_rate;
+} ssnes_dsp_info_t;
+
+typedef struct ssnes_dsp_output
+{
+   // The DSP plugin has to provide the buffering for the output samples.
+   // This is for performance reasons to avoid redundant copying of data.
+   // The samples are laid out in interleaving order: LRLRLRLR
+   // The range of the samples are [-1.0, 1.0]. 
+   // This range cannot be exceeded without horrible audio glitches.
+   const float *samples;
+   // Frames which the DSP plugin outputted for the current process.
+   // One frame is here defined as a combined sample of 
+   // left and right channels. 
+   // (I.e. 44.1kHz, 16bit stereo will have 
+   // 88.2k samples/sec and 44.1k frames/sec.)
+   unsigned frames;
+
+   // If true, the DSP plugin did not resample the input audio, 
+   // and requests resampling to the proper frequency to be 
+   // performed outside the plugin.
+   // If false, 
+   // it is assumed that the output has the same sample rate as the input.
+   int should_resample;
+} ssnes_dsp_output_t;
+
+typedef struct ssnes_dsp_input
+{
+   // Input data for the DSP. The samples are interleaved in order: LRLRLRLR
+   const float *samples;
+   // Number of frames for input data.
+   // One frame is here defined as a combined sample of 
+   // left and right channels. 
+   // (I.e. 44.1kHz, 16bit stereo will have 
+   // 88.2k samples/sec and 44.1k frames/sec.)
+   unsigned frames;
+} ssnes_dsp_input_t;
+
+typedef struct ssnes_dsp_plugin
+{
+   // Creates a handle of the plugin. Returns NULL if failed.
+   void* (*init)(const ssnes_dsp_info_t *info);
+
+   // Processes input data. 
+   // The plugin is allowed to return variable sizes for output data.
+   void (*process)(void *data, ssnes_dsp_output_t *output, 
+         const ssnes_dsp_input_t *input);
+
+   // Frees the handle.
+   void (*free)(void *data);
+} ssnes_dsp_plugin_t;
+
+SSNES_API_EXPORT const ssnes_dsp_plugin_t* SSNES_API_CALLTYPE 
+   ssnes_dsp_plugin_init(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

driver.c

@@ -146,6 +146,60 @@ void uninit_drivers(void)
    uninit_audio();
 }
 
+static void init_dsp_plugin(void)
+{
+   if (!(*g_settings.audio.dsp_plugin))
+      return;
+
+   g_extern.audio_data.dsp_lib = dylib_load(g_settings.audio.dsp_plugin);
+   if (!g_extern.audio_data.dsp_lib)
+   {
+      SSNES_ERR("Failed to open DSP plugin: \"%s\" ...\n", g_settings.audio.dsp_plugin);
+      return;
+   }
+
+   const ssnes_dsp_plugin_t* (*SSNES_API_CALLTYPE plugin_init)(void) = dylib_proc(g_extern.audio_data.dsp_lib, "ssnes_dsp_plugin_init");
+   if (!plugin_init)
+   {
+      SSNES_ERR("Failed to find symbol \"ssnes_dsp_plugin_init\" in DSP plugin.\n");
+      dylib_close(g_extern.audio_data.dsp_lib);
+      g_extern.audio_data.dsp_lib = NULL;
+      return;
+   }
+
+   g_extern.audio_data.dsp_plugin = plugin_init();
+   if (!g_extern.audio_data.dsp_plugin)
+   {
+      SSNES_ERR("Failed to get a valid DSP plugin.\n");
+      dylib_close(g_extern.audio_data.dsp_lib);
+      g_extern.audio_data.dsp_lib = NULL;
+      return;
+   }
+
+   ssnes_dsp_info_t info = {
+      .input_rate = g_settings.audio.in_rate,
+      .output_rate = g_settings.audio.out_rate
+   };
+   g_extern.audio_data.dsp_handle = g_extern.audio_data.dsp_plugin->init(&info);
+   if (!g_extern.audio_data.dsp_handle)
+   {
+      SSNES_ERR("Failed to init DSP plugin.\n");
+      dylib_close(g_extern.audio_data.dsp_lib);
+      g_extern.audio_data.dsp_plugin = NULL;
+      g_extern.audio_data.dsp_lib = NULL;
+      return;
+   }
+}
+
+static void deinit_dsp_plugin(void)
+{
+   if (g_extern.audio_data.dsp_lib && g_extern.audio_data.dsp_plugin)
+   {
+      g_extern.audio_data.dsp_plugin->free(g_extern.audio_data.dsp_handle);
+      dylib_close(g_extern.audio_data.dsp_lib);
+   }
+}
+
 #define AUDIO_CHUNK_SIZE_BLOCKING 64
 #define AUDIO_CHUNK_SIZE_NONBLOCKING 2048 // So we don't get complete line-noise when fast-forwarding audio.
 #define AUDIO_MAX_RATIO 16
@@ -196,6 +250,8 @@ void init_audio(void)
    g_extern.audio_data.data_ptr = 0;
    assert((g_extern.audio_data.outsamples = malloc(max_bufsamples * sizeof(float) * AUDIO_MAX_RATIO)));
    assert((g_extern.audio_data.conv_outsamples = malloc(max_bufsamples * sizeof(int16_t) * AUDIO_MAX_RATIO)));
+
+   init_dsp_plugin();
 }
 
 void uninit_audio(void)
@@ -221,6 +277,8 @@ void uninit_audio(void)
    free(g_extern.audio_data.data); g_extern.audio_data.data = NULL;
    free(g_extern.audio_data.outsamples); g_extern.audio_data.outsamples = NULL;
    free(g_extern.audio_data.conv_outsamples); g_extern.audio_data.conv_outsamples = NULL;
+
+   deinit_dsp_plugin();
 }
 
 #ifdef HAVE_DYLIB

general.h

@@ -30,6 +30,7 @@
 #include "netplay.h"
 #include "dynamic.h"
 #include "cheats.h"
+#include "audio/ext/ssnes_dsp.h"
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
@@ -103,6 +104,8 @@ struct settings
       unsigned latency;
       bool sync;
       int src_quality;
+
+      char dsp_plugin[256];
    } audio;
 
    struct
@@ -191,6 +194,10 @@ struct global
 
       float *outsamples;
       int16_t *conv_outsamples;
+
+      dylib_t dsp_lib;
+      const ssnes_dsp_plugin_t *dsp_plugin;
+      void *dsp_handle;
    } audio_data;
 
    struct

settings.c

@@ -367,6 +367,7 @@ static void parse_config_file(void)
 
    CONFIG_GET_STRING(video.driver, "video_driver");
    CONFIG_GET_STRING(audio.driver, "audio_driver");
+   CONFIG_GET_STRING(audio.dsp_plugin, "audio_dsp_plugin");
    CONFIG_GET_STRING(input.driver, "input_driver");
    CONFIG_GET_STRING(libsnes, "libsnes_path");
 

ssnes.c

@@ -152,58 +152,85 @@ static void audio_sample(uint16_t left, uint16_t right)
    }
 #endif
 
+   const float *output_data = NULL;
+   unsigned output_frames = 0;
+
    g_extern.audio_data.data[g_extern.audio_data.data_ptr++] = (float)(int16_t)left/0x8000; 
    g_extern.audio_data.data[g_extern.audio_data.data_ptr++] = (float)(int16_t)right/0x8000;
 
-   if (g_extern.audio_data.data_ptr >= g_extern.audio_data.chunk_size)
-   {
+   if (g_extern.audio_data.data_ptr < g_extern.audio_data.chunk_size)
+      return;
 
-      if (g_extern.frame_is_reverse) // Disable fucked up audio when rewinding...
-         memset(g_extern.audio_data.data, 0, g_extern.audio_data.chunk_size * sizeof(float));
+   ssnes_dsp_input_t dsp_input = {
+      .samples = g_extern.audio_data.data,
+      .frames = g_extern.audio_data.data_ptr / 2
+   };
+
+   ssnes_dsp_output_t dsp_output = {
+      .should_resample = SSNES_TRUE
+   };
+
+   if (g_extern.audio_data.dsp_plugin)
+      g_extern.audio_data.dsp_plugin->process(g_extern.audio_data.dsp_handle, &dsp_output, &dsp_input);
+
+   if (g_extern.frame_is_reverse) // Disable fucked up audio when rewinding...
+      memset(g_extern.audio_data.data, 0, g_extern.audio_data.chunk_size * sizeof(float));
 
 #ifdef HAVE_SRC
-      SRC_DATA src_data = {
+   SRC_DATA src_data = {
 #else
-      struct hermite_data src_data = {
+   struct hermite_data src_data = {
 #endif
-         .data_in = g_extern.audio_data.data,
-         .data_out = g_extern.audio_data.outsamples,
-         .input_frames = g_extern.audio_data.chunk_size / 2,
-         .output_frames = g_extern.audio_data.chunk_size * 8,
-         .end_of_input = 0,
-         .src_ratio = (double)g_settings.audio.out_rate / (double)g_settings.audio.in_rate,
-      };
+      .data_in = dsp_output.samples ? dsp_output.samples : g_extern.audio_data.data,
+      .data_out = g_extern.audio_data.outsamples,
+      .input_frames = dsp_output.samples ? dsp_output.frames : (g_extern.audio_data.chunk_size / 2),
+      .output_frames = g_extern.audio_data.chunk_size * 8,
+      .end_of_input = 0,
+      .src_ratio = (double)g_settings.audio.out_rate / (double)g_settings.audio.in_rate,
+   };
 
+   if (dsp_output.should_resample)
+   {
 #ifdef HAVE_SRC
       src_process(g_extern.audio_data.source, &src_data);
 #else
       hermite_process(g_extern.audio_data.source, &src_data);
 #endif
-      if (g_extern.audio_data.use_float)
-      {
-         if (driver.audio->write(driver.audio_data, g_extern.audio_data.outsamples, src_data.output_frames_gen * sizeof(float) * 2) < 0)
-         {
-            fprintf(stderr, "SSNES [ERROR]: Audio backend failed to write. Will continue without sound.\n");
-            g_extern.audio_active = false;
-         }
-      }
-      else
-      {
-         for (unsigned i = 0; i < src_data.output_frames_gen * 2; i++)
-         {
-            int32_t val = g_extern.audio_data.outsamples[i] * 0x8000;
-            g_extern.audio_data.conv_outsamples[i] = (val > 0x7FFF) ? 0x7FFF : (val < -0x8000 ? -0x8000 : (int16_t)val);
-         }
 
-         if (driver.audio->write(driver.audio_data, g_extern.audio_data.conv_outsamples, src_data.output_frames_gen * sizeof(int16_t) * 2) < 0)
-         {
-            fprintf(stderr, "SSNES [ERROR]: Audio backend failed to write. Will continue without sound.\n");
-            g_extern.audio_active = false;
-         }
-      }
-
-      g_extern.audio_data.data_ptr = 0;
+      output_data = g_extern.audio_data.outsamples;
+      output_frames = src_data.output_frames_gen;
    }
+   else
+   {
+      output_data = dsp_output.samples;
+      output_frames = dsp_output.frames;
+   }
+
+
+   if (g_extern.audio_data.use_float)
+   {
+      if (driver.audio->write(driver.audio_data, g_extern.audio_data.outsamples, src_data.output_frames_gen * sizeof(float) * 2) < 0)
+      {
+         fprintf(stderr, "SSNES [ERROR]: Audio backend failed to write. Will continue without sound.\n");
+         g_extern.audio_active = false;
+      }
+   }
+   else
+   {
+      for (unsigned i = 0; i < src_data.output_frames_gen * 2; i++)
+      {
+         int32_t val = output_data[i] * 0x8000;
+         g_extern.audio_data.conv_outsamples[i] = (val > 0x7FFF) ? 0x7FFF : (val < -0x8000 ? -0x8000 : (int16_t)val);
+      }
+
+      if (driver.audio->write(driver.audio_data, g_extern.audio_data.conv_outsamples, output_frames * sizeof(int16_t) * 2) < 0)
+      {
+         fprintf(stderr, "SSNES [ERROR]: Audio backend failed to write. Will continue without sound.\n");
+         g_extern.audio_active = false;
+      }
+   }
+
+   g_extern.audio_data.data_ptr = 0;
 }
 
 static void input_poll(void)

ssnes.cfg

@@ -105,6 +105,9 @@
 # Override the default audio device the audio_driver uses. This is driver dependant. E.g. ALSA wants a PCM device, OSS wants a path (e.g. /dev/dsp), Jack wants portnames (e.g. system:playback1,system:playback_2), and so on ...
 # audio_device =
 
+# External DSP plugin that processes audio before it's sent to the driver.
+# audio_dsp_plugin =
+
 # Will sync (block) on audio. Recommended.
 # audio_sync = true