audio: enable pitch correction by default when playing fast

Apparently this is what users want. When playing with normal speed,
nothing is done. When playing slower than normal, resampling is used
instead, because scaletempo (which does the pitch correction) adds
too many artifacts.

1 files changed, 37 insertions, 2 deletions

diff --git a/player/audio.c b/player/audio.c
index f532f1167b..969b0ca816 100644
--- a/player/audio.c
+++ b/player/audio.c
@@ -88,6 +88,23 @@ int reinit_audio_filters(struct MPContext *mpctx)
     return 1;
 }
 
+static int try_filter(struct MPContext *mpctx,
+                      char *name, char *label, char **args)
+{
+    struct dec_audio *d_audio = mpctx->d_audio;
+
+    if (af_find_by_label(d_audio->afilter, label))
+        return 0;
+
+    struct af_instance *af = af_add(d_audio->afilter, name, args);
+    if (!af)
+        return -1;
+
+    af->label = talloc_strdup(af, label);
+
+    return 1;
+}
+
 void set_playback_speed(struct MPContext *mpctx, double new_speed)
 {
     struct MPOpts *opts = mpctx->opts;
@@ -97,8 +114,23 @@ void set_playback_speed(struct MPContext *mpctx, double new_speed)
 
     opts->playback_speed = new_speed;
 
-    if (mpctx->d_audio)
-        recreate_audio_filters(mpctx);
+    if (!mpctx->d_audio)
+        return;
+
+    if (new_speed > 1.0 && opts->pitch_correction) {
+        if (!af_control_any_rev(mpctx->d_audio->afilter,
+                                AF_CONTROL_SET_PLAYBACK_SPEED,
+                                &new_speed))
+        {
+            if (try_filter(mpctx, "scaletempo", "playback-speed", NULL) < 0)
+                return;
+        }
+    } else {
+        if (af_remove_by_label(mpctx->d_audio->afilter, "playback-speed") < 0)
+            return;
+    }
+
+    recreate_audio_filters(mpctx);
 }
 
 void reset_audio_state(struct MPContext *mpctx)
@@ -155,6 +187,7 @@ void reinit_audio_chain(struct MPContext *mpctx)
         return;
     }
 
+    // Weak gapless audio: drain AO on decoder format changes
     if (mpctx->ao_decoder_fmt && (mpctx->initialized_flags & INITIALIZED_AO) &&
         !mp_audio_config_equals(mpctx->ao_decoder_fmt, &in_format) &&
         opts->gapless_audio < 0)
@@ -222,6 +255,8 @@ void reinit_audio_chain(struct MPContext *mpctx)
     if (recreate_audio_filters(mpctx) < 0)
         goto init_error;
 
+    set_playback_speed(mpctx, opts->playback_speed);
+
     return;
 
 init_error: