From 3cb4116243e54b0452d88c70a7acd4af17cf8d02 Mon Sep 17 00:00:00 2001
From: wm4 <wm4@nowhere>
Date: Sun, 10 Nov 2013 23:05:51 +0100
Subject: ao: add ao_play_silence, use for ao_alsa and ao_oss

Also add a corresponding function to audio/format.c, which fills an
audio block with silence.
---
 audio/format.c      |  6 ++++++
 audio/format.h      |  5 +++++
 audio/out/ao.c      | 12 ++++++++++++
 audio/out/ao.h      |  2 ++
 audio/out/ao_alsa.c |  8 ++------
 audio/out/ao_oss.c  | 11 ++++-------
 6 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/audio/format.c b/audio/format.c
index b933d07e16..448b670671 100644
--- a/audio/format.c
+++ b/audio/format.c
@@ -127,3 +127,9 @@ int af_str2fmt_short(bstr str)
     }
     return 0;
 }
+
+void af_fill_silence(void *dst, size_t bytes, int format)
+{
+    bool us = (format & AF_FORMAT_SIGN_MASK) == AF_FORMAT_US;
+    memset(dst, us ? 0x80 : 0, bytes);
+}
diff --git a/audio/format.h b/audio/format.h
index 3a80a601c5..95e792340c 100644
--- a/audio/format.h
+++ b/audio/format.h
@@ -134,6 +134,9 @@ enum af_format {
     (AF_FORMAT_IS_AC3(fmt) ||      \
      ((fmt) & AF_FORMAT_SPECIAL_MASK) == AF_FORMAT_S_IEC61937)
 
+#define AF_FORMAT_IS_SPECIAL(fmt) \
+    ((fmt & AF_FORMAT_SPECIAL_MASK) != 0)
+
 struct af_fmt_entry {
     const char *name;
     int format;
@@ -152,4 +155,6 @@ int af_fmt_seconds_to_bytes(int format, float seconds, int channels, int sampler
 
 bool af_fmt_is_valid(int format);
 
+void af_fill_silence(void *dst, size_t bytes, int format);
+
 #endif /* MPLAYER_AF_FORMAT_H */
diff --git a/audio/out/ao.c b/audio/out/ao.c
index 88f0b2223d..55db34becb 100644
--- a/audio/out/ao.c
+++ b/audio/out/ao.c
@@ -250,6 +250,18 @@ void ao_resume(struct ao *ao)
         ao->driver->resume(ao);
 }
 
+int ao_play_silence(struct ao *ao, int samples)
+{
+    if (samples <= 0 || AF_FORMAT_IS_SPECIAL(ao->format))
+        return 0;
+    int s = ao->channels.num * (af_fmt2bits(ao->format) / 8);
+    char *p = talloc_size(NULL, samples * s);
+    af_fill_silence(p, samples * s, ao->format);
+    int r = ao_play(ao, p, samples * s, 0);
+    talloc_free(p);
+    return r;
+}
+
 bool ao_chmap_sel_adjust(struct ao *ao, const struct mp_chmap_sel *s,
                          struct mp_chmap *map)
 {
diff --git a/audio/out/ao.h b/audio/out/ao.h
index c6ad5455d2..159a6adc0f 100644
--- a/audio/out/ao.h
+++ b/audio/out/ao.h
@@ -103,6 +103,8 @@ void ao_reset(struct ao *ao);
 void ao_pause(struct ao *ao);
 void ao_resume(struct ao *ao);
 
+int ao_play_silence(struct ao *ao, int samples);
+
 bool ao_chmap_sel_adjust(struct ao *ao, const struct mp_chmap_sel *s,
                          struct mp_chmap *map);
 bool ao_chmap_sel_get_def(struct ao *ao, const struct mp_chmap_sel *s,
diff --git a/audio/out/ao_alsa.c b/audio/out/ao_alsa.c
index bdfd8fae76..5816ee5f5f 100644
--- a/audio/out/ao_alsa.c
+++ b/audio/out/ao_alsa.c
@@ -78,7 +78,6 @@ struct priv {
     } while (0)
 
 static float get_delay(struct ao *ao);
-static int play(struct ao *ao, void *data, int len, int flags);
 static void uninit(struct ao *ao, bool immed);
 
 static void alsa_error_handler(const char *file, int line, const char *function,
@@ -612,11 +611,8 @@ static void audio_resume(struct ao *ao)
         MP_VERBOSE(ao, "resume not supported by hardware\n");
         err = snd_pcm_prepare(p->alsa);
         CHECK_ALSA_ERROR("pcm prepare error");
-        if (p->prepause_frames) {
-            void *silence = calloc(p->prepause_frames, p->bytes_per_sample);
-            play(ao, silence, p->prepause_frames * p->bytes_per_sample, 0);
-            free(silence);
-        }
+        if (p->prepause_frames)
+            ao_play_silence(ao, p->prepause_frames);
     }
 
 alsa_error: ;
diff --git a/audio/out/ao_oss.c b/audio/out/ao_oss.c
index 556f3c25c9..db9847851d 100644
--- a/audio/out/ao_oss.c
+++ b/audio/out/ao_oss.c
@@ -508,16 +508,13 @@ static int play(struct ao *ao, void *data, int len, int flags)
 static void audio_resume(struct ao *ao)
 {
     struct priv *p = ao->priv;
-    int fillcnt;
 #ifndef SNDCTL_DSP_RESET
     reset(ao);
 #endif
-    fillcnt = get_space(ao) - p->prepause_space;
-    if (fillcnt > 0 && !(ao->format & AF_FORMAT_SPECIAL_MASK)) {
-        void *silence = calloc(fillcnt, 1);
-        play(ao, silence, fillcnt, 0);
-        free(silence);
-    }
+    int fillframes = (get_space(ao) - p->prepause_space) /
+                     (af_fmt2bits(ao->format) / 8 * ao->channels.num);
+    if (fillframes > 0)
+        ao_play_silence(ao, fillframes);
 }
 
 // return: delay in seconds between first and last sample in buffer
-- 
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