Add WSOLA pitch compensation to timewarp

src/modules/core/producer_timewarp.c

@@ -1,6 +1,6 @@
 /*
  * producer_timewarp.c -- modify speed and direction of a clip
- * Copyright (C) 2015-2021 Meltytech, LLC
+ * Copyright (C) 2015-2026 Meltytech, LLC
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -34,6 +34,7 @@ typedef struct
     mlt_profile clip_profile;
     mlt_properties clip_parameters;
     mlt_filter pitch_filter;
+    int pitch_wsola;
 } private_data;
 
 // Private Functions
@@ -89,6 +90,15 @@ static int producer_probe(mlt_producer parent)
     return 1;
 }
 
+// "wsola" prefers the WSOLA filter for pitch compensation. Anything else,
+// including no value, prefers rubberband. Either way, the other filter is used
+// when the preferred one is not available.
+static int use_wsola_pitch(mlt_properties producer_properties)
+{
+    const char *method = mlt_properties_get(producer_properties, "warp_pitch_method");
+    return method && !strcmp(method, "wsola");
+}
+
 static int producer_get_audio(mlt_frame frame,
                               void **buffer,
                               mlt_audio_format *format,
@@ -169,11 +179,19 @@ static int producer_get_frame(mlt_producer producer, mlt_frame_ptr frame, int in
             // Pitch compensation does not work well for speed *reduction* of 1/10th or less.
             if (mlt_properties_get_int(producer_properties, "warp_pitch")
                 && fabs(pdata->speed) >= 0.1) {
+                int wsola = use_wsola_pitch(producer_properties);
+                if (pdata->pitch_filter && pdata->pitch_wsola != wsola) {
+                    mlt_filter_close(pdata->pitch_filter);
+                    pdata->pitch_filter = NULL;
+                }
                 if (!pdata->pitch_filter) {
-                    pdata->pitch_filter = mlt_factory_filter(mlt_service_profile(
-                                                                 MLT_PRODUCER_SERVICE(producer)),
-                                                             "rbpitch",
-                                                             NULL);
+                    mlt_profile profile = mlt_service_profile(MLT_PRODUCER_SERVICE(producer));
+                    const char *preferred = wsola ? "wsola" : "rbpitch";
+                    const char *fallback = wsola ? "rbpitch" : "wsola";
+                    pdata->pitch_filter = mlt_factory_filter(profile, preferred, NULL);
+                    if (!pdata->pitch_filter)
+                        pdata->pitch_filter = mlt_factory_filter(profile, fallback, NULL);
+                    pdata->pitch_wsola = wsola;
                 }
                 if (pdata->pitch_filter) {
                     mlt_properties_set_double(MLT_FILTER_PROPERTIES(pdata->pitch_filter),

src/modules/core/producer_timewarp.yml

@@ -59,6 +59,21 @@ parameters:
     mutable: no
     default: 0
 
+  - identifier: warp_pitch_method
+    title: Pitch Compensation Method
+    type: string
+    description: >
+      The filter used to shift the pitch of the resampled audio when
+      warp_pitch is enabled: "rubberband" (filter rbpitch) or "wsola" (filter
+      wsola, which needs no external library). When it is not set, rubberband
+      is used if it is available and wsola otherwise. If the selected filter is
+      not available, the other one is used.
+    readonly: no
+    mutable: yes
+    values:
+      - rubberband
+      - wsola
+
   - identifier: warp_speed
     title: Warp Speed
     type: float

src/modules/plus/CMakeLists.txt

@@ -26,12 +26,15 @@ add_library(mltplus MODULE
   filter_text.c
   filter_threshold.c
   filter_timer.c
+  filter_wsola.cpp
   interp.h
   producer_blipflash.c
   producer_count.c
   producer_pgm.c
   producer_subtitle.c
   transition_affine.c
+  wsola/sinc_resampler.cpp
+  wsola/wsola_algorithm.cpp
 )
 
 file(GLOB YML "*.yml")
@@ -64,6 +67,12 @@ else()
   target_compile_definitions(mltplus PRIVATE USE_INTERNAL_LIBEBUR128)
 endif()
 
+# Keep the floating point behavior of the Chromium original (no -ffast-math).
+if(NOT MSVC)
+  set_source_files_properties(filter_wsola.cpp wsola/sinc_resampler.cpp wsola/wsola_algorithm.cpp
+    PROPERTIES COMPILE_OPTIONS -fno-fast-math)
+endif()
+
 set_target_properties(mltplus PROPERTIES LIBRARY_OUTPUT_DIRECTORY "${MLT_MODULE_OUTPUT_DIRECTORY}")
 
 install(TARGETS mltplus LIBRARY DESTINATION ${MLT_INSTALL_MODULE_DIR})
@@ -94,6 +103,7 @@ install(FILES
   filter_text.yml
   filter_threshold.yml
   filter_timer.yml
+  filter_wsola.yml
   producer_blipflash.yml
   producer_count.yml
   producer_pgm.yml

src/modules/plus/factory.c

@@ -153,6 +153,11 @@ extern mlt_filter filter_fft_init(mlt_profile profile,
                                   char *arg);
 #endif
 
+extern mlt_filter filter_wsola_init(mlt_profile profile,
+                                    mlt_service_type type,
+                                    const char *id,
+                                    char *arg);
+
 static mlt_properties metadata(mlt_service_type type, const char *id, void *data)
 {
     char file[PATH_MAX];
@@ -187,6 +192,7 @@ MLTPLUS_EXPORT MLT_REPOSITORY
     MLT_REGISTER(mlt_service_filter_type, "text", filter_text_init);
     MLT_REGISTER(mlt_service_filter_type, "threshold", filter_threshold_init);
     MLT_REGISTER(mlt_service_filter_type, "timer", filter_timer_init);
+    MLT_REGISTER(mlt_service_filter_type, "wsola", filter_wsola_init);
     MLT_REGISTER(mlt_service_producer_type, "blipflash", producer_blipflash_init);
     MLT_REGISTER(mlt_service_producer_type, "count", producer_count_init);
     MLT_REGISTER(mlt_service_producer_type, "pgm", producer_pgm_init);
@@ -252,6 +258,7 @@ MLTPLUS_EXPORT MLT_REPOSITORY
     MLT_REGISTER_METADATA(mlt_service_filter_type, "text", metadata, "filter_text.yml");
     MLT_REGISTER_METADATA(mlt_service_filter_type, "threshold", metadata, "filter_threshold.yml");
     MLT_REGISTER_METADATA(mlt_service_filter_type, "timer", metadata, "filter_timer.yml");
+    MLT_REGISTER_METADATA(mlt_service_filter_type, "wsola", metadata, "filter_wsola.yml");
     MLT_REGISTER_METADATA(mlt_service_producer_type,
                           "blipflash",
                           metadata,