Don't include common.h from avutil.h
[ffmpeg.git] / libavfilter / avfiltergraph.c
index 2123c28..525a1dc 100644 (file)
@@ -1,22 +1,22 @@
 /*
  * filter graphs
- * copyright (c) 2008 Vitor Sessak
- * copyright (c) 2007 Bobby Bingham
+ * Copyright (c) 2008 Vitor Sessak
+ * Copyright (c) 2007 Bobby Bingham
  *
- * This file is part of FFmpeg.
+ * This file is part of Libav.
  *
- * FFmpeg is free software; you can redistribute it and/or
+ * Libav is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
- * FFmpeg is distributed in the hope that it will be useful,
+ * Libav is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
- * License along with FFmpeg; if not, write to the Free Software
+ * License along with Libav; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 
 #include "avfilter.h"
 #include "avfiltergraph.h"
+#include "formats.h"
+#include "internal.h"
 
-void avfilter_graph_destroy(AVFilterGraph *graph)
+#include "libavutil/audioconvert.h"
+#include "libavutil/avassert.h"
+#include "libavutil/common.h"
+#include "libavutil/log.h"
+
+static const AVClass filtergraph_class = {
+    .class_name = "AVFilterGraph",
+    .item_name  = av_default_item_name,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+AVFilterGraph *avfilter_graph_alloc(void)
 {
-    for(; graph->filter_count > 0; graph->filter_count --)
-        avfilter_destroy(graph->filters[graph->filter_count - 1]);
-    av_freep(&graph->scale_sws_opts);
-    av_freep(&graph->filters);
+    AVFilterGraph *ret = av_mallocz(sizeof(AVFilterGraph));
+    if (!ret)
+        return NULL;
+    ret->av_class = &filtergraph_class;
+    return ret;
+}
+
+void avfilter_graph_free(AVFilterGraph **graph)
+{
+    if (!*graph)
+        return;
+    for (; (*graph)->filter_count > 0; (*graph)->filter_count--)
+        avfilter_free((*graph)->filters[(*graph)->filter_count - 1]);
+    av_freep(&(*graph)->scale_sws_opts);
+    av_freep(&(*graph)->filters);
+    av_freep(graph);
 }
 
 int avfilter_graph_add_filter(AVFilterGraph *graph, AVFilterContext *filter)
@@ -47,29 +72,58 @@ int avfilter_graph_add_filter(AVFilterGraph *graph, AVFilterContext *filter)
     return 0;
 }
 
-int avfilter_graph_check_validity(AVFilterGraph *graph, AVClass *log_ctx)
+int avfilter_graph_create_filter(AVFilterContext **filt_ctx, AVFilter *filt,
+                                 const char *name, const char *args, void *opaque,
+                                 AVFilterGraph *graph_ctx)
+{
+    int ret;
+
+    if ((ret = avfilter_open(filt_ctx, filt, name)) < 0)
+        goto fail;
+    if ((ret = avfilter_init_filter(*filt_ctx, args, opaque)) < 0)
+        goto fail;
+    if ((ret = avfilter_graph_add_filter(graph_ctx, *filt_ctx)) < 0)
+        goto fail;
+    return 0;
+
+fail:
+    if (*filt_ctx)
+        avfilter_free(*filt_ctx);
+    *filt_ctx = NULL;
+    return ret;
+}
+
+/**
+ * Check for the validity of graph.
+ *
+ * A graph is considered valid if all its input and output pads are
+ * connected.
+ *
+ * @return 0 in case of success, a negative value otherwise
+ */
+static int graph_check_validity(AVFilterGraph *graph, AVClass *log_ctx)
 {
     AVFilterContext *filt;
     int i, j;
 
-    for (i=0; i < graph->filter_count; i++) {
+    for (i = 0; i < graph->filter_count; i++) {
         filt = graph->filters[i];
 
-        for (j = 0; j < filt->input_count; j++) {
+        for (j = 0; j < filt->nb_inputs; j++) {
             if (!filt->inputs[j] || !filt->inputs[j]->src) {
                 av_log(log_ctx, AV_LOG_ERROR,
                        "Input pad \"%s\" for the filter \"%s\" of type \"%s\" not connected to any source\n",
                        filt->input_pads[j].name, filt->name, filt->filter->name);
-                return -1;
+                return AVERROR(EINVAL);
             }
         }
 
-        for (j = 0; j < filt->output_count; j++) {
+        for (j = 0; j < filt->nb_outputs; j++) {
             if (!filt->outputs[j] || !filt->outputs[j]->dst) {
                 av_log(log_ctx, AV_LOG_ERROR,
                        "Output pad \"%s\" for the filter \"%s\" of type \"%s\" not connected to any destination\n",
                        filt->output_pads[j].name, filt->name, filt->filter->name);
-                return -1;
+                return AVERROR(EINVAL);
             }
         }
     }
@@ -77,7 +131,12 @@ int avfilter_graph_check_validity(AVFilterGraph *graph, AVClass *log_ctx)
     return 0;
 }
 
-int avfilter_graph_config_links(AVFilterGraph *graph, AVClass *log_ctx)
+/**
+ * Configure all the links of graphctx.
+ *
+ * @return 0 in case of success, a negative value otherwise
+ */
+static int graph_config_links(AVFilterGraph *graph, AVClass *log_ctx)
 {
     AVFilterContext *filt;
     int i, ret;
@@ -85,7 +144,7 @@ int avfilter_graph_config_links(AVFilterGraph *graph, AVClass *log_ctx)
     for (i=0; i < graph->filter_count; i++) {
         filt = graph->filters[i];
 
-        if (!filt->output_count) {
+        if (!filt->nb_outputs) {
             if ((ret = avfilter_config_links(filt)))
                 return ret;
         }
@@ -98,8 +157,8 @@ AVFilterContext *avfilter_graph_get_filter(AVFilterGraph *graph, char *name)
 {
     int i;
 
-    for(i = 0; i < graph->filter_count; i ++)
-        if(graph->filters[i]->name && !strcmp(name, graph->filters[i]->name))
+    for (i = 0; i < graph->filter_count; i++)
+        if (graph->filters[i]->name && !strcmp(name, graph->filters[i]->name))
             return graph->filters[i];
 
     return NULL;
@@ -107,54 +166,111 @@ AVFilterContext *avfilter_graph_get_filter(AVFilterGraph *graph, char *name)
 
 static int query_formats(AVFilterGraph *graph, AVClass *log_ctx)
 {
-    int i, j;
-    int scaler_count = 0;
-    char inst_name[30];
+    int i, j, ret;
+    int scaler_count = 0, resampler_count = 0;
 
     /* ask all the sub-filters for their supported media formats */
-    for(i = 0; i < graph->filter_count; i ++) {
-        if(graph->filters[i]->filter->query_formats)
+    for (i = 0; i < graph->filter_count; i++) {
+        if (graph->filters[i]->filter->query_formats)
             graph->filters[i]->filter->query_formats(graph->filters[i]);
         else
-            avfilter_default_query_formats(graph->filters[i]);
+            ff_default_query_formats(graph->filters[i]);
     }
 
     /* go through and merge as many format lists as possible */
-    for(i = 0; i < graph->filter_count; i ++) {
+    for (i = 0; i < graph->filter_count; i++) {
         AVFilterContext *filter = graph->filters[i];
 
-        for(j = 0; j < filter->input_count; j ++) {
+        for (j = 0; j < filter->nb_inputs; j++) {
             AVFilterLink *link = filter->inputs[j];
-            if(link && link->in_formats != link->out_formats) {
-                if(!avfilter_merge_formats(link->in_formats,
-                                           link->out_formats)) {
-                    AVFilterContext *scale;
-                    char scale_args[256];
-                    /* couldn't merge format lists. auto-insert scale filter */
+            int convert_needed = 0;
+
+            if (!link)
+                continue;
+
+            if (link->in_formats != link->out_formats &&
+                !ff_merge_formats(link->in_formats,
+                                        link->out_formats))
+                convert_needed = 1;
+            if (link->type == AVMEDIA_TYPE_AUDIO) {
+                if (link->in_channel_layouts != link->out_channel_layouts &&
+                    !ff_merge_channel_layouts(link->in_channel_layouts,
+                                              link->out_channel_layouts))
+                    convert_needed = 1;
+                if (link->in_samplerates != link->out_samplerates &&
+                    !ff_merge_samplerates(link->in_samplerates,
+                                          link->out_samplerates))
+                    convert_needed = 1;
+            }
+
+            if (convert_needed) {
+                AVFilterContext *convert;
+                AVFilter *filter;
+                AVFilterLink *inlink, *outlink;
+                char scale_args[256];
+                char inst_name[30];
+
+                /* couldn't merge format lists. auto-insert conversion filter */
+                switch (link->type) {
+                case AVMEDIA_TYPE_VIDEO:
+                    if (!(filter = avfilter_get_by_name("scale"))) {
+                        av_log(log_ctx, AV_LOG_ERROR, "'scale' filter "
+                               "not present, cannot convert pixel formats.\n");
+                        return AVERROR(EINVAL);
+                    }
+
                     snprintf(inst_name, sizeof(inst_name), "auto-inserted scaler %d",
                              scaler_count++);
-                    avfilter_open(&scale, avfilter_get_by_name("scale"), inst_name);
-
                     snprintf(scale_args, sizeof(scale_args), "0:0:%s", graph->scale_sws_opts);
-                    if(!scale || scale->filter->init(scale, scale_args, NULL) ||
-                                 avfilter_insert_filter(link, scale, 0, 0)) {
-                        avfilter_destroy(scale);
-                        return -1;
+                    if ((ret = avfilter_graph_create_filter(&convert, filter,
+                                                            inst_name, scale_args, NULL,
+                                                            graph)) < 0)
+                        return ret;
+                    break;
+                case AVMEDIA_TYPE_AUDIO:
+                    if (!(filter = avfilter_get_by_name("resample"))) {
+                        av_log(log_ctx, AV_LOG_ERROR, "'resample' filter "
+                               "not present, cannot convert audio formats.\n");
+                        return AVERROR(EINVAL);
                     }
 
-                    if (avfilter_graph_add_filter(graph, scale) < 0)
-                        return -1;
-
-                    scale->filter->query_formats(scale);
-                    if (((link = scale-> inputs[0]) &&
-                         !avfilter_merge_formats(link->in_formats, link->out_formats)) ||
-                        ((link = scale->outputs[0]) &&
-                         !avfilter_merge_formats(link->in_formats, link->out_formats))) {
-                        av_log(log_ctx, AV_LOG_ERROR,
-                               "Impossible to convert between the formats supported by the filter "
-                               "'%s' and the filter '%s'\n", link->src->name, link->dst->name);
-                        return -1;
-                    }
+                    snprintf(inst_name, sizeof(inst_name), "auto-inserted resampler %d",
+                             resampler_count++);
+                    if ((ret = avfilter_graph_create_filter(&convert, filter,
+                                                            inst_name, NULL, NULL, graph)) < 0)
+                        return ret;
+                    break;
+                default:
+                    return AVERROR(EINVAL);
+                }
+
+                if ((ret = avfilter_insert_filter(link, convert, 0, 0)) < 0)
+                    return ret;
+
+                convert->filter->query_formats(convert);
+                inlink  = convert->inputs[0];
+                outlink = convert->outputs[0];
+                if (!ff_merge_formats( inlink->in_formats,  inlink->out_formats) ||
+                    !ff_merge_formats(outlink->in_formats, outlink->out_formats))
+                    ret |= AVERROR(ENOSYS);
+                if (inlink->type == AVMEDIA_TYPE_AUDIO &&
+                    (!ff_merge_samplerates(inlink->in_samplerates,
+                                           inlink->out_samplerates) ||
+                     !ff_merge_channel_layouts(inlink->in_channel_layouts,
+                                               inlink->out_channel_layouts)))
+                    ret |= AVERROR(ENOSYS);
+                if (outlink->type == AVMEDIA_TYPE_AUDIO &&
+                    (!ff_merge_samplerates(outlink->in_samplerates,
+                                           outlink->out_samplerates) ||
+                     !ff_merge_channel_layouts(outlink->in_channel_layouts,
+                                               outlink->out_channel_layouts)))
+                    ret |= AVERROR(ENOSYS);
+
+                if (ret < 0) {
+                    av_log(log_ctx, AV_LOG_ERROR,
+                           "Impossible to convert between the formats supported by the filter "
+                           "'%s' and the filter '%s'\n", link->src->name, link->dst->name);
+                    return ret;
                 }
             }
         }
@@ -163,42 +279,430 @@ static int query_formats(AVFilterGraph *graph, AVClass *log_ctx)
     return 0;
 }
 
-static void pick_format(AVFilterLink *link)
+static int pick_format(AVFilterLink *link)
 {
-    if(!link || !link->in_formats)
-        return;
+    if (!link || !link->in_formats)
+        return 0;
 
     link->in_formats->format_count = 1;
     link->format = link->in_formats->formats[0];
 
-    avfilter_formats_unref(&link->in_formats);
-    avfilter_formats_unref(&link->out_formats);
+    if (link->type == AVMEDIA_TYPE_AUDIO) {
+        if (!link->in_samplerates->format_count) {
+            av_log(link->src, AV_LOG_ERROR, "Cannot select sample rate for"
+                   " the link between filters %s and %s.\n", link->src->name,
+                   link->dst->name);
+            return AVERROR(EINVAL);
+        }
+        link->in_samplerates->format_count = 1;
+        link->sample_rate = link->in_samplerates->formats[0];
+
+        if (!link->in_channel_layouts->nb_channel_layouts) {
+            av_log(link->src, AV_LOG_ERROR, "Cannot select channel layout for"
+                   "the link between filters %s and %s.\n", link->src->name,
+                   link->dst->name);
+            return AVERROR(EINVAL);
+        }
+        link->in_channel_layouts->nb_channel_layouts = 1;
+        link->channel_layout = link->in_channel_layouts->channel_layouts[0];
+    }
+
+    ff_formats_unref(&link->in_formats);
+    ff_formats_unref(&link->out_formats);
+    ff_formats_unref(&link->in_samplerates);
+    ff_formats_unref(&link->out_samplerates);
+    ff_channel_layouts_unref(&link->in_channel_layouts);
+    ff_channel_layouts_unref(&link->out_channel_layouts);
+
+    return 0;
+}
+
+#define REDUCE_FORMATS(fmt_type, list_type, list, var, nb, add_format) \
+do {                                                                   \
+    for (i = 0; i < filter->nb_inputs; i++) {                          \
+        AVFilterLink *link = filter->inputs[i];                        \
+        fmt_type fmt;                                                  \
+                                                                       \
+        if (!link->out_ ## list || link->out_ ## list->nb != 1)        \
+            continue;                                                  \
+        fmt = link->out_ ## list->var[0];                              \
+                                                                       \
+        for (j = 0; j < filter->nb_outputs; j++) {                     \
+            AVFilterLink *out_link = filter->outputs[j];               \
+            list_type *fmts;                                           \
+                                                                       \
+            if (link->type != out_link->type ||                        \
+                out_link->in_ ## list->nb == 1)                        \
+                continue;                                              \
+            fmts = out_link->in_ ## list;                              \
+                                                                       \
+            if (!out_link->in_ ## list->nb) {                          \
+                add_format(&out_link->in_ ##list, fmt);                \
+                break;                                                 \
+            }                                                          \
+                                                                       \
+            for (k = 0; k < out_link->in_ ## list->nb; k++)            \
+                if (fmts->var[k] == fmt) {                             \
+                    fmts->var[0]  = fmt;                               \
+                    fmts->nb = 1;                                      \
+                    ret = 1;                                           \
+                    break;                                             \
+                }                                                      \
+        }                                                              \
+    }                                                                  \
+} while (0)
+
+static int reduce_formats_on_filter(AVFilterContext *filter)
+{
+    int i, j, k, ret = 0;
+
+    REDUCE_FORMATS(int,      AVFilterFormats,        formats,         formats,
+                   format_count, ff_add_format);
+    REDUCE_FORMATS(int,      AVFilterFormats,        samplerates,     formats,
+                   format_count, ff_add_format);
+    REDUCE_FORMATS(uint64_t, AVFilterChannelLayouts, channel_layouts,
+                   channel_layouts, nb_channel_layouts, ff_add_channel_layout);
+
+    return ret;
+}
+
+static void reduce_formats(AVFilterGraph *graph)
+{
+    int i, reduced;
+
+    do {
+        reduced = 0;
+
+        for (i = 0; i < graph->filter_count; i++)
+            reduced |= reduce_formats_on_filter(graph->filters[i]);
+    } while (reduced);
+}
+
+static void swap_samplerates_on_filter(AVFilterContext *filter)
+{
+    AVFilterLink *link = NULL;
+    int sample_rate;
+    int i, j;
+
+    for (i = 0; i < filter->nb_inputs; i++) {
+        link = filter->inputs[i];
+
+        if (link->type == AVMEDIA_TYPE_AUDIO &&
+            link->out_samplerates->format_count == 1)
+            break;
+    }
+    if (i == filter->nb_inputs)
+        return;
+
+    sample_rate = link->out_samplerates->formats[0];
+
+    for (i = 0; i < filter->nb_outputs; i++) {
+        AVFilterLink *outlink = filter->outputs[i];
+        int best_idx, best_diff = INT_MAX;
+
+        if (outlink->type != AVMEDIA_TYPE_AUDIO ||
+            outlink->in_samplerates->format_count < 2)
+            continue;
+
+        for (j = 0; j < outlink->in_samplerates->format_count; j++) {
+            int diff = abs(sample_rate - outlink->in_samplerates->formats[j]);
+
+            if (diff < best_diff) {
+                best_diff = diff;
+                best_idx  = j;
+            }
+        }
+        FFSWAP(int, outlink->in_samplerates->formats[0],
+               outlink->in_samplerates->formats[best_idx]);
+    }
+}
+
+static void swap_samplerates(AVFilterGraph *graph)
+{
+    int i;
+
+    for (i = 0; i < graph->filter_count; i++)
+        swap_samplerates_on_filter(graph->filters[i]);
+}
+
+#define CH_CENTER_PAIR (AV_CH_FRONT_LEFT_OF_CENTER | AV_CH_FRONT_RIGHT_OF_CENTER)
+#define CH_FRONT_PAIR  (AV_CH_FRONT_LEFT           | AV_CH_FRONT_RIGHT)
+#define CH_STEREO_PAIR (AV_CH_STEREO_LEFT          | AV_CH_STEREO_RIGHT)
+#define CH_WIDE_PAIR   (AV_CH_WIDE_LEFT            | AV_CH_WIDE_RIGHT)
+#define CH_SIDE_PAIR   (AV_CH_SIDE_LEFT            | AV_CH_SIDE_RIGHT)
+#define CH_DIRECT_PAIR (AV_CH_SURROUND_DIRECT_LEFT | AV_CH_SURROUND_DIRECT_RIGHT)
+#define CH_BACK_PAIR   (AV_CH_BACK_LEFT            | AV_CH_BACK_RIGHT)
+
+/* allowable substitutions for channel pairs when comparing layouts,
+ * ordered by priority for both values */
+static const uint64_t ch_subst[][2] = {
+    { CH_FRONT_PAIR,      CH_CENTER_PAIR     },
+    { CH_FRONT_PAIR,      CH_WIDE_PAIR       },
+    { CH_FRONT_PAIR,      AV_CH_FRONT_CENTER },
+    { CH_CENTER_PAIR,     CH_FRONT_PAIR      },
+    { CH_CENTER_PAIR,     CH_WIDE_PAIR       },
+    { CH_CENTER_PAIR,     AV_CH_FRONT_CENTER },
+    { CH_WIDE_PAIR,       CH_FRONT_PAIR      },
+    { CH_WIDE_PAIR,       CH_CENTER_PAIR     },
+    { CH_WIDE_PAIR,       AV_CH_FRONT_CENTER },
+    { AV_CH_FRONT_CENTER, CH_FRONT_PAIR      },
+    { AV_CH_FRONT_CENTER, CH_CENTER_PAIR     },
+    { AV_CH_FRONT_CENTER, CH_WIDE_PAIR       },
+    { CH_SIDE_PAIR,       CH_DIRECT_PAIR     },
+    { CH_SIDE_PAIR,       CH_BACK_PAIR       },
+    { CH_SIDE_PAIR,       AV_CH_BACK_CENTER  },
+    { CH_BACK_PAIR,       CH_DIRECT_PAIR     },
+    { CH_BACK_PAIR,       CH_SIDE_PAIR       },
+    { CH_BACK_PAIR,       AV_CH_BACK_CENTER  },
+    { AV_CH_BACK_CENTER,  CH_BACK_PAIR       },
+    { AV_CH_BACK_CENTER,  CH_DIRECT_PAIR     },
+    { AV_CH_BACK_CENTER,  CH_SIDE_PAIR       },
+};
+
+static void swap_channel_layouts_on_filter(AVFilterContext *filter)
+{
+    AVFilterLink *link = NULL;
+    int i, j, k;
+
+    for (i = 0; i < filter->nb_inputs; i++) {
+        link = filter->inputs[i];
+
+        if (link->type == AVMEDIA_TYPE_AUDIO &&
+            link->out_channel_layouts->nb_channel_layouts == 1)
+            break;
+    }
+    if (i == filter->nb_inputs)
+        return;
+
+    for (i = 0; i < filter->nb_outputs; i++) {
+        AVFilterLink *outlink = filter->outputs[i];
+        int best_idx, best_score = INT_MIN, best_count_diff = INT_MAX;
+
+        if (outlink->type != AVMEDIA_TYPE_AUDIO ||
+            outlink->in_channel_layouts->nb_channel_layouts < 2)
+            continue;
+
+        for (j = 0; j < outlink->in_channel_layouts->nb_channel_layouts; j++) {
+            uint64_t  in_chlayout = link->out_channel_layouts->channel_layouts[0];
+            uint64_t out_chlayout = outlink->in_channel_layouts->channel_layouts[j];
+            int  in_channels      = av_get_channel_layout_nb_channels(in_chlayout);
+            int out_channels      = av_get_channel_layout_nb_channels(out_chlayout);
+            int count_diff        = out_channels - in_channels;
+            int matched_channels, extra_channels;
+            int score = 0;
+
+            /* channel substitution */
+            for (k = 0; k < FF_ARRAY_ELEMS(ch_subst); k++) {
+                uint64_t cmp0 = ch_subst[k][0];
+                uint64_t cmp1 = ch_subst[k][1];
+                if (( in_chlayout & cmp0) && (!(out_chlayout & cmp0)) &&
+                    (out_chlayout & cmp1) && (!( in_chlayout & cmp1))) {
+                    in_chlayout  &= ~cmp0;
+                    out_chlayout &= ~cmp1;
+                    /* add score for channel match, minus a deduction for
+                       having to do the substitution */
+                    score += 10 * av_get_channel_layout_nb_channels(cmp1) - 2;
+                }
+            }
+
+            /* no penalty for LFE channel mismatch */
+            if ( (in_chlayout & AV_CH_LOW_FREQUENCY) &&
+                (out_chlayout & AV_CH_LOW_FREQUENCY))
+                score += 10;
+            in_chlayout  &= ~AV_CH_LOW_FREQUENCY;
+            out_chlayout &= ~AV_CH_LOW_FREQUENCY;
+
+            matched_channels = av_get_channel_layout_nb_channels(in_chlayout &
+                                                                 out_chlayout);
+            extra_channels   = av_get_channel_layout_nb_channels(out_chlayout &
+                                                                 (~in_chlayout));
+            score += 10 * matched_channels - 5 * extra_channels;
+
+            if (score > best_score ||
+                (count_diff < best_count_diff && score == best_score)) {
+                best_score = score;
+                best_idx   = j;
+                best_count_diff = count_diff;
+            }
+        }
+        FFSWAP(uint64_t, outlink->in_channel_layouts->channel_layouts[0],
+               outlink->in_channel_layouts->channel_layouts[best_idx]);
+    }
+
 }
 
-static void pick_formats(AVFilterGraph *graph)
+static void swap_channel_layouts(AVFilterGraph *graph)
 {
+    int i;
+
+    for (i = 0; i < graph->filter_count; i++)
+        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 < graph->filter_count; i ++) {
+    for (i = 0; i < filter->nb_inputs; i++) {
+        link = filter->inputs[i];
+
+        if (link->type == AVMEDIA_TYPE_AUDIO &&
+            link->out_formats->format_count == 1)
+            break;
+    }
+    if (i == filter->nb_inputs)
+        return;
+
+    format = link->out_formats->formats[0];
+    bps    = av_get_bytes_per_sample(format);
+
+    for (i = 0; i < filter->nb_outputs; i++) {
+        AVFilterLink *outlink = filter->outputs[i];
+        int best_idx = -1, 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;
+            }
+        }
+        av_assert0(best_idx >= 0);
+        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;
+
+    for (i = 0; i < graph->filter_count; i++) {
         AVFilterContext *filter = graph->filters[i];
 
-        for(j = 0; j < filter->input_count; j ++)
-            pick_format(filter->inputs[j]);
-        for(j = 0; j < filter->output_count; j ++)
-            pick_format(filter->outputs[j]);
+        for (j = 0; j < filter->nb_inputs; j++)
+            if ((ret = pick_format(filter->inputs[j])) < 0)
+                return ret;
+        for (j = 0; j < filter->nb_outputs; j++)
+            if ((ret = pick_format(filter->outputs[j])) < 0)
+                return ret;
     }
+    return 0;
 }
 
-int avfilter_graph_config_formats(AVFilterGraph *graph, AVClass *log_ctx)
+/**
+ * Configure the formats of all the links in the graph.
+ */
+static int graph_config_formats(AVFilterGraph *graph, AVClass *log_ctx)
 {
+    int ret;
+
     /* find supported formats from sub-filters, and merge along links */
-    if(query_formats(graph, log_ctx))
-        return -1;
+    if ((ret = query_formats(graph, log_ctx)) < 0)
+        return ret;
 
     /* Once everything is merged, it's possible that we'll still have
-     * multiple valid media format choices. We pick the first one. */
-    pick_formats(graph);
+     * multiple valid media format choices. We try to minimize the amount
+     * of format conversion inside filters */
+    reduce_formats(graph);
+
+    /* 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);
+
+    if ((ret = pick_formats(graph)) < 0)
+        return ret;
+
+    return 0;
+}
+
+static int graph_insert_fifos(AVFilterGraph *graph, AVClass *log_ctx)
+{
+    AVFilterContext *f;
+    int i, j, ret;
+    int fifo_count = 0;
+
+    for (i = 0; i < graph->filter_count; i++) {
+        f = graph->filters[i];
+
+        for (j = 0; j < f->nb_inputs; j++) {
+            AVFilterLink *link = f->inputs[j];
+            AVFilterContext *fifo_ctx;
+            AVFilter *fifo;
+            char name[32];
+
+            if (!link->dstpad->needs_fifo)
+                continue;
+
+            fifo = f->inputs[j]->type == AVMEDIA_TYPE_VIDEO ?
+                   avfilter_get_by_name("fifo") :
+                   avfilter_get_by_name("afifo");
+
+            snprintf(name, sizeof(name), "auto-inserted fifo %d", fifo_count++);
+
+            ret = avfilter_graph_create_filter(&fifo_ctx, fifo, name, NULL,
+                                               NULL, graph);
+            if (ret < 0)
+                return ret;
+
+            ret = avfilter_insert_filter(link, fifo_ctx, 0, 0);
+            if (ret < 0)
+                return ret;
+        }
+    }
 
     return 0;
 }
 
+int avfilter_graph_config(AVFilterGraph *graphctx, void *log_ctx)
+{
+    int ret;
+
+    if ((ret = graph_check_validity(graphctx, log_ctx)))
+        return ret;
+    if ((ret = graph_insert_fifos(graphctx, log_ctx)) < 0)
+        return ret;
+    if ((ret = graph_config_formats(graphctx, log_ctx)))
+        return ret;
+    if ((ret = graph_config_links(graphctx, log_ctx)))
+        return ret;
+
+    return 0;
+}