@@ -461,6 +461,74 @@ static void swap_channel_layouts(AVFilterGraph *graph)

         swap_channel_layouts_on_filter(graph->filters[i]);

 }

+static void swap_sample_fmts_on_filter(AVFilterContext *filter)

+{

+    AVFilterLink *link = NULL;

+    int format, bps;

+    int i, j;

+

+    for (i = 0; i < filter->input_count; i++) {

+        link = filter->inputs[i];

+

+        if (link->type == AVMEDIA_TYPE_AUDIO &&

+            link->out_formats->format_count == 1)

+            break;

+    }

+    if (i == filter->input_count)

+        return;

+

+    format = link->out_formats->formats[0];

+    bps    = av_get_bytes_per_sample(format);

+

+    for (i = 0; i < filter->output_count; i++) {

+        AVFilterLink *outlink = filter->outputs[i];

+        int best_idx, best_score = INT_MIN;

+

+        if (outlink->type != AVMEDIA_TYPE_AUDIO ||

+            outlink->in_formats->format_count < 2)

+            continue;

+

+        for (j = 0; j < outlink->in_formats->format_count; j++) {

+            int out_format = outlink->in_formats->formats[j];

+            int out_bps    = av_get_bytes_per_sample(out_format);

+            int score;

+

+            if (av_get_packed_sample_fmt(out_format) == format ||

+                av_get_planar_sample_fmt(out_format) == format) {

+                best_idx   = j;

+                break;

+            }

+

+            /* for s32 and float prefer double to prevent loss of information */

+            if (bps == 4 && out_bps == 8) {

+                best_idx = j;

+                break;

+            }

+

+            /* prefer closest higher or equal bps */

+            score = -abs(out_bps - bps);

+            if (out_bps >= bps)

+                score += INT_MAX/2;

+

+            if (score > best_score) {

+                best_score = score;

+                best_idx   = j;

+            }

+        }

+        FFSWAP(int, outlink->in_formats->formats[0],

+               outlink->in_formats->formats[best_idx]);

+    }

+}

+

+static void swap_sample_fmts(AVFilterGraph *graph)

+{

+    int i;

+

+    for (i = 0; i < graph->filter_count; i++)

+        swap_sample_fmts_on_filter(graph->filters[i]);

+

+}

+

 static int pick_formats(AVFilterGraph *graph)

 {

     int i, j, ret;

@@ -491,8 +559,9 @@ int ff_avfilter_graph_config_formats(AVFilterGraph *graph, AVClass *log_ctx)

      * of format conversion inside filters */

     reduce_formats(graph);

-    /* for audio filters, ensure the best sample rate and channel layout

+    /* for audio filters, ensure the best format, sample rate and channel layout

      * is selected */

+    swap_sample_fmts(graph);

     swap_samplerates(graph);

     swap_channel_layouts(graph);