Index: input/input.h
===================================================================
--- input/input.h	（版本 23550）
+++ input/input.h	（工作副本）
@@ -95,6 +95,7 @@
 #define MP_CMD_TV_STEP_FREQ 93
 #define MP_CMD_TV_TELETEXT_ADD_DEC 94
 #define MP_CMD_TV_TELETEXT_GO_LINK 95
+#define MP_CMD_BALANCE 96
 
 #define MP_CMD_GUI_EVENTS       5000
 #define MP_CMD_GUI_LOADFILE     5001
Index: input/input.c
===================================================================
--- input/input.c	（版本 23550）
+++ input/input.c	（工作副本）
@@ -71,6 +71,7 @@
   { MP_CMD_OSD_SHOW_TEXT, "osd_show_text", 1, { {MP_CMD_ARG_STRING, {0}}, {MP_CMD_ARG_INT,{-1}}, {MP_CMD_ARG_INT,{0}}, {-1,{0}} } },
   { MP_CMD_OSD_SHOW_PROPERTY_TEXT, "osd_show_property_text",1, { {MP_CMD_ARG_STRING, {0}}, {MP_CMD_ARG_INT,{-1}}, {MP_CMD_ARG_INT,{0}}, {-1,{0}} } },
   { MP_CMD_VOLUME, "volume", 1, { { MP_CMD_ARG_FLOAT,{0} }, {MP_CMD_ARG_INT,{0}}, {-1,{0}} } },
+  { MP_CMD_BALANCE, "balance", 1, { { MP_CMD_ARG_FLOAT,{0} }, {MP_CMD_ARG_INT,{0}}, {-1,{0}} } },
   { MP_CMD_MIXER_USEMASTER, "use_master", 0, { {-1,{0}} } },
   { MP_CMD_MUTE, "mute", 0, { {MP_CMD_ARG_INT,{-1}}, {-1,{0}} } },
   { MP_CMD_CONTRAST, "contrast",1,  { {MP_CMD_ARG_INT,{0}}, {MP_CMD_ARG_INT,{0}}, {-1,{0}} } },
@@ -363,6 +364,8 @@
   { { '/', 0 }, "volume -1" },
   { { '0', 0 }, "volume 1" },
   { { '*', 0 }, "volume 1" },
+  { { '(', 0 }, "balance -0.1" },
+  { { ')', 0 }, "balance 0.1" },
   { { 'm', 0 }, "mute" },
   { { '1', 0 }, "contrast -1" },
   { { '2', 0 }, "contrast 1" },
Index: etc/input.conf
===================================================================
--- etc/input.conf	（版本 23550）
+++ etc/input.conf	（工作副本）
@@ -51,6 +51,8 @@
 6 hue 1
 7 saturation -1
 8 saturation 1
+( balance -0.1          # adjust audio balance in favor of left
+) balance +0.1          #                                  right
 d frame_drop
 r sub_pos -1            # move subtitles up
 t sub_pos +1            #                down
Index: etc/menu.conf
===================================================================
--- etc/menu.conf	（版本 23550）
+++ etc/menu.conf	（工作副本）
@@ -33,6 +33,7 @@
 
 <pref name="audio_pref" title="Audio">
       <e property="volume" name="Volume"/>
+      <e property="balance" name="Balance"/>
       <e property="mute" name="Mute"/>
       <e property="audio_delay" name="Delay"/>
 </pref>
Index: command.c
===================================================================
--- command.c	（版本 23550）
+++ command.c	（工作副本）
@@ -571,6 +571,57 @@
     return m_property_int_ro(prop, action, arg, mpctx->sh_audio->channels);
 }
 
+/// Balance (RW)
+static int mp_property_balance(m_option_t * prop, int action, void *arg,
+			      MPContext * mpctx)
+{
+    float bal;
+
+    if (!mpctx->sh_audio || mpctx->sh_audio->channels < 2)
+	return M_PROPERTY_UNAVAILABLE;
+
+    switch (action) {
+    case M_PROPERTY_GET:
+	if (!arg)
+	    return M_PROPERTY_ERROR;
+	mixer_getbalance(&mpctx->mixer, arg);
+	return M_PROPERTY_OK;
+    case M_PROPERTY_PRINT: {
+	    char** str = arg;
+	    if (!arg)
+		return M_PROPERTY_ERROR;
+	    mixer_getbalance(&mpctx->mixer, &bal);
+	    if (bal == 0.f)
+		*str = strdup("center");
+	    else if (bal == -1.f)
+		*str = strdup("left only");
+	    else if (bal == 1.f)
+		*str = strdup("right only");
+	    else {
+		unsigned right = (bal + 1.f) / 2.f * 100.f;
+		*str = malloc(sizeof("left xxx%, right xxx%"));
+		sprintf(*str, "left %d%%, right %d%%", 100 - right, right);
+	    }
+	    return M_PROPERTY_OK;
+	}
+    case M_PROPERTY_STEP_UP:
+    case M_PROPERTY_STEP_DOWN:
+	mixer_getbalance(&mpctx->mixer, &bal);
+	bal += (arg ? *(float*)arg : .1f) *
+	    (action == M_PROPERTY_STEP_UP ? 1.f : -1.f);
+	M_PROPERTY_CLAMP(prop, bal);
+	mixer_setbalance(&mpctx->mixer, bal);
+	return M_PROPERTY_OK;
+    case M_PROPERTY_SET:
+	if (!arg)
+	    return M_PROPERTY_ERROR;
+	M_PROPERTY_CLAMP(prop, *(float*)arg);
+	mixer_setbalance(&mpctx->mixer, *(float*)arg);
+	return M_PROPERTY_OK;
+    }
+    return M_PROPERTY_NOT_IMPLEMENTED;
+}
+
 /// Selected audio id (RW)
 static int mp_property_audio(m_option_t * prop, int action, void *arg,
 			     MPContext * mpctx)
@@ -1596,6 +1647,8 @@
      0, 0, 0, NULL },
     { "switch_audio", mp_property_audio, CONF_TYPE_INT,
      CONF_RANGE, -2, MAX_A_STREAMS - 1, NULL },
+    { "balance", mp_property_balance, CONF_TYPE_FLOAT,
+     M_OPT_RANGE, -1, 1, NULL },
 
     // Video
     { "fullscreen", mp_property_fullscreen, CONF_TYPE_FLAG,
@@ -1750,6 +1803,7 @@
     { "mute", MP_CMD_MUTE, 1, 0, -1, MSGTR_MuteStatus },
     { "audio_delay", MP_CMD_AUDIO_DELAY, 0, 0, -1, MSGTR_AVDelayStatus },
     { "switch_audio", MP_CMD_SWITCH_AUDIO, 1, 0, -1, MSGTR_OSDAudio },
+    { "balance", MP_CMD_BALANCE, 0, OSD_BALANCE, -1, MSGTR_Balance },
     // video
     { "fullscreen", MP_CMD_VO_FULLSCREEN, 1, 0, -1, NULL },
     { "panscan", MP_CMD_PANSCAN, 0, OSD_PANSCAN, -1, MSGTR_Panscan },
Index: mixer.h
===================================================================
--- mixer.h	（版本 23550）
+++ mixer.h	（工作副本）
@@ -23,6 +23,8 @@
 void mixer_decvolume(mixer_t *mixer);
 void mixer_getbothvolume(mixer_t *mixer, float *b);
 void mixer_mute(mixer_t *mixer);
+void mixer_getbalance(mixer_t *mixer, float *bal);
+void mixer_setbalance(mixer_t *mixer, float bal);
 
 //extern void mixer_setbothvolume( int v );
 #define mixer_setbothvolume(m, v) mixer_setvolume(m, v, v)
Index: mixer.c
===================================================================
--- mixer.c	（版本 23550）
+++ mixer.c	（工作副本）
@@ -17,6 +17,7 @@
 char * mixer_channel=NULL;
 int soft_vol = 0;
 float soft_vol_max = 110.0;
+static af_instance_t* af_pan_balance;
 
 void mixer_getvolume(mixer_t *mixer, float *l, float *r)
 {
@@ -118,3 +119,78 @@
     mixer->muted=1;
    }
 }
+
+void mixer_getbalance(mixer_t *mixer, float *val)
+{
+  float level[AF_NCH];
+  af_control_ext_t arg_ext = { .arg = level };
+  *val = 0.f;
+
+  if (!af_pan_balance)
+    return;
+
+  arg_ext.ch = 0;
+  if (!af_pan_balance->control(af_pan_balance,
+        AF_CONTROL_PAN_LEVEL | AF_CONTROL_GET, &arg_ext))
+    return;
+  if (level[1]) {
+    *val = level[1];
+    return;
+  }
+
+  arg_ext.ch = 1;
+  if (!af_pan_balance->control(af_pan_balance,
+        AF_CONTROL_PAN_LEVEL | AF_CONTROL_GET, &arg_ext))
+    return;
+  if (level[0])
+    *val = -level[0];
+}
+
+void mixer_setbalance(mixer_t *mixer, float val)
+{
+  float level[AF_NCH];
+  int nout;
+  af_control_ext_t arg_ext = { .arg = level };
+
+  if(!mixer->audio_out || !mixer->afilter)
+    return;
+
+  if (!af_pan_balance) {
+    if ((af_pan_balance = af_add(mixer->afilter, "pan"))) {
+      int i;
+      af_init(mixer->afilter);
+      /* make all other channels pass thru since by default pan blocks all */
+      memset(level, 0, sizeof(level));
+      for (i = 2; i < AF_NCH; i++) {
+        arg_ext.ch = i;
+        level[i] = 1.f;
+        af_pan_balance->control(af_pan_balance,
+            AF_CONTROL_PAN_LEVEL | AF_CONTROL_SET, &arg_ext);
+        level[i] = 0.f;
+      }
+    } else {
+      mp_msg(MSGT_GLOBAL, MSGL_ERR, MSGTR_NoBalance);
+      return;
+    }
+  }
+
+  af_pan_balance->control(af_pan_balance,
+     AF_CONTROL_PAN_NOUT | AF_CONTROL_GET, &nout);
+  if (nout < 2) {
+    mp_msg(MSGT_GLOBAL, MSGL_WARN, MSGTR_MonoBalance);
+    return;
+  }
+
+  arg_ext.ch = 0;
+  level[0] = min(1.f, 1.f - val);
+  level[1] = max(0.f, val);
+  af_pan_balance->control(af_pan_balance,
+      AF_CONTROL_PAN_LEVEL | AF_CONTROL_SET, &arg_ext);
+
+  arg_ext.ch = 1;
+  level[0] = max(0.f, -val);
+  level[1] = min(1.f, 1 + val);
+  af_pan_balance->control(af_pan_balance,
+      AF_CONTROL_PAN_LEVEL | AF_CONTROL_SET, &arg_ext);
+}
+
Index: libvo/sub.h
===================================================================
--- libvo/sub.h	（版本 23550）
+++ libvo/sub.h	（工作副本）
@@ -91,6 +91,7 @@
 #define OSD_VOLUME 0x09
 #define OSD_BRIGHTNESS 0x0A
 #define OSD_HUE 0x0B
+#define OSD_BALANCE 0x0C
 #define OSD_PANSCAN 0x50
 
 #define OSD_PB_START 0x10
Index: libvo/sub.c
===================================================================
--- libvo/sub.c	（版本 23550）
+++ libvo/sub.c	（工作副本）
@@ -58,9 +58,10 @@
     MSGTR_VO_SUB_Saturation,
     MSGTR_VO_SUB_Volume,
     MSGTR_VO_SUB_Brightness,
-    MSGTR_VO_SUB_Hue
+    MSGTR_VO_SUB_Hue,
+    MSGTR_VO_SUB_Balance
 };
-char * __sub_osd_names_short[] ={ "", "|>", "||", "[]", "<<" , ">>", "", "", "", "", "", ""};
+char * __sub_osd_names_short[] ={ "", "|>", "||", "[]", "<<" , ">>", "", "", "", "", "", "", "" };
 
 //static int vo_font_loaded=-1;
 font_desc_t* vo_font=NULL;
Index: help/help_mp-en.h
===================================================================
--- help/help_mp-en.h	（版本 23550）
+++ help/help_mp-en.h	（工作副本）
@@ -231,6 +231,7 @@
 #define MSGTR_Contrast "Contrast"
 #define MSGTR_Saturation "Saturation"
 #define MSGTR_Hue "Hue"
+#define MSGTR_Balance "Balance"
 
 // property state
 #define MSGTR_MuteStatus "Mute: %s"
@@ -706,6 +707,8 @@
 
 #define MSGTR_InsertingAfVolume "[Mixer] No hardware mixing, inserting volume filter.\n"
 #define MSGTR_NoVolume "[Mixer] No volume control available.\n"
+#define MSGTR_NoBalance "[Mixer] No balance control available.\n"
+#define MSGTR_MonoBalance "[Mixer] Pan filter has mono output; no balance control available.\n"
 
 // ====================== GUI messages/buttons ========================
 
@@ -1077,6 +1080,7 @@
 #define MSGTR_VO_SUB_Volume "Volume"
 #define MSGTR_VO_SUB_Brightness "Brightness"
 #define MSGTR_VO_SUB_Hue "Hue"
+#define MSGTR_VO_SUB_Balance "Balance"
 
 // vo_xv.c
 #define MSGTR_VO_XV_ImagedimTooHigh "Source image dimensions are too high: %ux%u (maximum is %ux%u)\n"
Index: DOCS/man/en/mplayer.1
===================================================================
--- DOCS/man/en/mplayer.1	（版本 23550）
+++ DOCS/man/en/mplayer.1	（工作副本）
@@ -238,6 +238,8 @@
 Decrease/\:increase volume.
 .IPs "9 and 0"
 Decrease/\:increase volume.
+.IPs "( and )"
+Adjust audio balance in favor of left/\:right channel.
 .IPs "m\ \ \ \ "
 Mute sound.
 .IPs "_ (MPEG-TS and libavformat only)"
Index: DOCS/tech/slave.txt
===================================================================
--- DOCS/tech/slave.txt	（版本 23550）
+++ DOCS/tech/slave.txt	（工作副本）
@@ -419,6 +419,7 @@
 metadata           str list                  X            list of metadata key/value
 metadata/*         string                    X            metadata values
 volume             float     0       100     X   X   X    change volume
+balance            float     -1      1       X   X   X    change audio balance
 mute               flag      0       1       X   X   X
 audio_delay        float     -100    100     X   X   X
 audio_format       int                       X