@@ -12023,6 +12023,9 @@ The expression can use the following variables:

 @item VOLUME

 Current max volume of channel in dB.

 @end table

+

+@item t

+If set, displays channel names. Default is enabled.

 @end table

 @section showwaves

@@ -23,6 +23,7 @@

 #include "libavutil/intreadwrite.h"

 #include "libavutil/opt.h"

 #include "libavutil/parseutils.h"

+#include "libavutil/xga_font_data.h"

 #include "avfilter.h"

 #include "formats.h"

 #include "audio.h"

@@ -38,6 +39,7 @@ typedef struct ShowVolumeContext {

     AVFrame *out;

     AVExpr *c_expr;

+    int draw_text;

 } ShowVolumeContext;

 #define OFFSET(x) offsetof(ShowVolumeContext, x)

@@ -51,6 +53,7 @@ static const AVOption showvolume_options[] = {

     { "h", "set channel height", OFFSET(h), AV_OPT_TYPE_INT, {.i64=20}, 1, 100, FLAGS },

     { "f", "set fade",           OFFSET(f), AV_OPT_TYPE_INT, {.i64=20}, 1, 255, FLAGS },

     { "c", "set volume color expression", OFFSET(color), AV_OPT_TYPE_STRING, {.str="if(gte(VOLUME,-2), if(gte(VOLUME,-1),0xff, 0xffff),0xff00)"}, 0, 0, FLAGS },

+    { "t", "display channel names", OFFSET(draw_text), AV_OPT_TYPE_INT, {.i64=1}, 0, 1, FLAGS },

     { NULL }

 };

@@ -133,6 +136,29 @@ static int config_output(AVFilterLink *outlink)

     return 0;

 }

+static void drawtext(AVFrame *pic, int x, int y, const char *txt)

+{

+    const uint8_t *font;

+    int font_height;

+    int i;

+

+    font = avpriv_cga_font,   font_height =  8;

+

+    for (i = 0; txt[i]; i++) {

+        int char_y, mask;

+        uint8_t *p = pic->data[0] + y*pic->linesize[0] + (x + i*8)*4;

+

+        for (char_y = 0; char_y < font_height; char_y++) {

+            for (mask = 0x80; mask; mask >>= 1) {

+                if (font[txt[i] * font_height + char_y] & mask)

+                    AV_WN32(p, ~AV_RN32(p));

+                p += 4;

+            }

+            p += pic->linesize[0] - 8*4;

+        }

+    }

+}

+

 static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)

 {

     AVFilterContext *ctx = inlink->dst;

@@ -183,6 +209,10 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)

             for (k = 0; k < s->w * max; k++)

                 AV_WN32A(dst + k * 4, color);

         }

+

+        if (s->h >= 8 && s->draw_text)

+            drawtext(s->out, 2, c * (s->h + s->b) + (s->h - 8) / 2,

+                     av_get_channel_name(av_channel_layout_extract_channel(insamples->channel_layout, c)));

     }

     av_frame_free(&insamples);