mixer: keep user volume setting when --softvol is used

When --softvol is enabled, the volume set by the "volume" property is
reset when changing to a new file or crossing ordered chapter boundaries.

Fix this by explicitly restoring the volume on audio reinitialization.
Now the behavior with --softvol should be the same as if a system mixer
is used, and the volume should be persistent across file changes.

This also works around an inconsistency with the mute flag. The frontend
assumed the mute flag is persistent across file changes, which was not
true with --softvol.

If not resetting the volume on playing new files is undesired, it can
be avoided by putting volume=100 in the mplayer config file.

3 files changed, 17 insertions, 0 deletions

diff --git a/mixer.c b/mixer.c
index ba58ed8a85..4c196e4bdf 100644
--- a/mixer.c
+++ b/mixer.c
@@ -35,6 +35,16 @@ char *mixer_channel = NULL;
 int soft_vol = 0;
 float soft_vol_max = 110.0;
 
+// Called after the audio filter chain is built or rebuilt.
+void mixer_reinit(mixer_t *mixer)
+{
+    if (mixer->restore_softvol) {
+        int muted = mixer->muted;
+        mixer_setvolume(mixer, mixer->softvol_l, mixer->softvol_r);
+        mixer->muted = muted;
+    }
+}
+
 void mixer_getvolume(mixer_t *mixer, float *l, float *r)
 {
     ao_control_vol_t vol;
@@ -76,6 +86,9 @@ void mixer_setvolume(mixer_t *mixer, float l, float r)
             // af_volume uses values in dB
             float db_vals[AF_NCH];
             int i;
+            mixer->softvol_l = l;
+            mixer->softvol_r = r;
+            mixer->restore_softvol = 1;
             db_vals[0] = (l / 100.0) * (soft_vol_max / 100.0);
             db_vals[1] = (r / 100.0) * (soft_vol_max / 100.0);
             for (i = 2; i < AF_NCH; i++)
diff --git a/mixer.h b/mixer.h
index 23c7f3ade0..473933ecbe 100644
--- a/mixer.h
+++ b/mixer.h
@@ -33,8 +33,11 @@ typedef struct mixer_s {
     int volstep;
     int muted;
     float last_l, last_r;
+    float softvol_l, softvol_r;
+    int restore_softvol;
 } mixer_t;
 
+void mixer_reinit(mixer_t *mixer);
 void mixer_getvolume(mixer_t *mixer, float *l, float *r);
 void mixer_setvolume(mixer_t *mixer, float l, float r);
 void mixer_incvolume(mixer_t *mixer);
diff --git a/mplayer.c b/mplayer.c
index d79d45f057..6b57c695e6 100644
--- a/mplayer.c
+++ b/mplayer.c
@@ -1448,6 +1448,7 @@ static int build_afilter_chain(struct MPContext *mpctx)
     result =  init_audio_filters(sh_audio, new_srate,
                                  &ao->samplerate, &ao->channels, &ao->format);
     mpctx->mixer.afilter = sh_audio->afilter;
+    mixer_reinit(&mpctx->mixer);
     return result;
 }