vf_setdar: make config_props work properly when called multiple times.
[ffmpeg.git] / libavfilter / avfiltergraph.c
index aee2b1f..9131026 100644 (file)
 /*
  * 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 <ctype.h>
 #include <string.h>
 
+#include "libavutil/avassert.h"
+#include "libavutil/avstring.h"
+#include "libavutil/channel_layout.h"
+#include "libavutil/common.h"
+#include "libavutil/log.h"
 #include "avfilter.h"
-#include "avfiltergraph.h"
+#include "formats.h"
+#include "internal.h"
 
-/**
- * For use in av_log
- */
-static const char *log_name(void *p)
+static const AVClass filtergraph_class = {
+    .class_name = "AVFilterGraph",
+    .item_name  = av_default_item_name,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+AVFilterGraph *avfilter_graph_alloc(void)
 {
-    return "Filter parser";
+    AVFilterGraph *ret = av_mallocz(sizeof(*ret));
+    if (!ret)
+        return NULL;
+    ret->av_class = &filtergraph_class;
+    return ret;
 }
 
-static const AVClass filter_parser_class = {
-    "Filter parser",
-    log_name
-};
+void ff_filter_graph_remove_filter(AVFilterGraph *graph, AVFilterContext *filter)
+{
+    int i;
+    for (i = 0; i < graph->nb_filters; i++) {
+        if (graph->filters[i] == filter) {
+            FFSWAP(AVFilterContext*, graph->filters[i],
+                   graph->filters[graph->nb_filters - 1]);
+            graph->nb_filters--;
+            return;
+        }
+    }
+}
 
-static const AVClass *log_ctx = &filter_parser_class;
+void avfilter_graph_free(AVFilterGraph **graph)
+{
+    if (!*graph)
+        return;
+
+    while ((*graph)->nb_filters)
+        avfilter_free((*graph)->filters[0]);
+
+    av_freep(&(*graph)->scale_sws_opts);
+    av_freep(&(*graph)->resample_lavr_opts);
+    av_freep(&(*graph)->filters);
+    av_freep(graph);
+}
 
-void avfilter_destroy_graph(AVFilterGraph *graph)
+#if FF_API_AVFILTER_OPEN
+int avfilter_graph_add_filter(AVFilterGraph *graph, AVFilterContext *filter)
 {
-    for(; graph->filter_count > 0; graph->filter_count --)
-        avfilter_destroy(graph->filters[graph->filter_count - 1]);
-    av_freep(&graph->filters);
+    AVFilterContext **filters = av_realloc(graph->filters,
+                                           sizeof(*filters) * (graph->nb_filters + 1));
+    if (!filters)
+        return AVERROR(ENOMEM);
+
+    graph->filters = filters;
+    graph->filters[graph->nb_filters++] = filter;
+
+#if FF_API_FOO_COUNT
+    graph->filter_count = graph->nb_filters;
+#endif
+
+    filter->graph = graph;
+
+    return 0;
 }
+#endif
 
-/* TODO: insert in sorted order */
-void avfilter_graph_add_filter(AVFilterGraph *graph, AVFilterContext *filter)
+int avfilter_graph_create_filter(AVFilterContext **filt_ctx, AVFilter *filt,
+                                 const char *name, const char *args, void *opaque,
+                                 AVFilterGraph *graph_ctx)
 {
-    graph->filters = av_realloc(graph->filters,
-                                sizeof(AVFilterContext*) * ++graph->filter_count);
-    graph->filters[graph->filter_count - 1] = filter;
+    int ret;
+
+    *filt_ctx = avfilter_graph_alloc_filter(graph_ctx, filt, name);
+    if (!*filt_ctx)
+        return AVERROR(ENOMEM);
+
+    ret = avfilter_init_str(*filt_ctx, args);
+    if (ret < 0)
+        goto fail;
+
+    return 0;
+
+fail:
+    if (*filt_ctx)
+        avfilter_free(*filt_ctx);
+    *filt_ctx = NULL;
+    return ret;
 }
 
-/* search intelligently, once we insert in order */
-AVFilterContext *avfilter_graph_get_filter(AVFilterGraph *graph, char *name)
+AVFilterContext *avfilter_graph_alloc_filter(AVFilterGraph *graph,
+                                             const AVFilter *filter,
+                                             const char *name)
 {
-    int i;
+    AVFilterContext **filters, *s;
 
-    if(!name)
+    s = ff_filter_alloc(filter, name);
+    if (!s)
         return NULL;
 
-    for(i = 0; i < graph->filter_count; i ++)
-        if(graph->filters[i]->name && !strcmp(name, graph->filters[i]->name))
+    filters = av_realloc(graph->filters, sizeof(*filters) * (graph->nb_filters + 1));
+    if (!filters) {
+        avfilter_free(s);
+        return NULL;
+    }
+
+    graph->filters = filters;
+    graph->filters[graph->nb_filters++] = s;
+
+#if FF_API_FOO_COUNT
+    graph->filter_count = graph->nb_filters;
+#endif
+
+    s->graph = graph;
+
+    return s;
+}
+
+/**
+ * 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->nb_filters; i++) {
+        filt = graph->filters[i];
+
+        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 AVERROR(EINVAL);
+            }
+        }
+
+        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 AVERROR(EINVAL);
+            }
+        }
+    }
+
+    return 0;
+}
+
+/**
+ * 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;
+
+    for (i = 0; i < graph->nb_filters; i++) {
+        filt = graph->filters[i];
+
+        if (!filt->nb_outputs) {
+            if ((ret = avfilter_config_links(filt)))
+                return ret;
+        }
+    }
+
+    return 0;
+}
+
+AVFilterContext *avfilter_graph_get_filter(AVFilterGraph *graph, char *name)
+{
+    int i;
+
+    for (i = 0; i < graph->nb_filters; i++)
+        if (graph->filters[i]->name && !strcmp(name, graph->filters[i]->name))
             return graph->filters[i];
 
     return NULL;
 }
 
-static int query_formats(AVFilterGraph *graph)
+static int query_formats(AVFilterGraph *graph, AVClass *log_ctx)
 {
-    int i, j;
+    int i, j, ret;
+    int scaler_count = 0, resampler_count = 0;
 
-    /* ask all the sub-filters for their supported colorspaces */
-    for(i = 0; i < graph->filter_count; i ++) {
-        if(graph->filters[i]->filter->query_formats)
+    /* ask all the sub-filters for their supported media formats */
+    for (i = 0; i < graph->nb_filters; 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->nb_filters; i++) {
         AVFilterContext *filter = graph->filters[i];
 
-        for(j = 0; j < filter->input_count; j ++) {
-            AVFilterLink *link;
-            if(!(link = filter->inputs[j]))
+        for (j = 0; j < filter->nb_inputs; j++) {
+            AVFilterLink *link = filter->inputs[j];
+            int convert_needed = 0;
+
+            if (!link)
                 continue;
-            if(link->in_formats != link->out_formats) {
-                if(!avfilter_merge_formats(link->in_formats,
-                                           link->out_formats)) {
-                    /* couldn't merge format lists. auto-insert scale filter */
-                    AVFilterContext *scale;
-
-                    if(!(scale =
-                         avfilter_open(avfilter_get_by_name("scale"), NULL)))
-                        return -1;
-                    if(scale->filter->init(scale, NULL, NULL) ||
-                       avfilter_insert_filter(link, scale, 0, 0)) {
-                        avfilter_destroy(scale);
-                        return -1;
+
+            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++);
+
+                    if ((ret = avfilter_graph_create_filter(&convert, filter,
+                                                            inst_name, graph->scale_sws_opts, 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);
                     }
 
-                    avfilter_graph_add_filter(graph, scale);
-                    scale->filter->query_formats(scale);
-                    if(!avfilter_merge_formats(scale-> inputs[0]->in_formats,
-                                              scale-> inputs[0]->out_formats) ||
-                       !avfilter_merge_formats(scale->outputs[0]->in_formats,
-                                              scale->outputs[0]->out_formats))
-                        return -1;
+                    snprintf(inst_name, sizeof(inst_name), "auto-inserted resampler %d",
+                             resampler_count++);
+                    scale_args[0] = '\0';
+                    if (graph->resample_lavr_opts)
+                        snprintf(scale_args, sizeof(scale_args), "%s",
+                                 graph->resample_lavr_opts);
+                    if ((ret = avfilter_graph_create_filter(&convert, filter,
+                                                            inst_name, scale_args,
+                                                            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;
                 }
             }
         }
@@ -121,389 +336,431 @@ static int query_formats(AVFilterGraph *graph)
     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;
 }
 
-static void pick_formats(AVFilterGraph *graph)
+#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;
+    int i, j, k, ret = 0;
 
-    for(i = 0; i < graph->filter_count; i ++) {
-        AVFilterContext *filter = graph->filters[i];
+    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);
 
-        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]);
-    }
+    return ret;
 }
 
-int avfilter_graph_config_formats(AVFilterGraph *graph)
+static void reduce_formats(AVFilterGraph *graph)
 {
-    /* find supported formats from sub-filters, and merge along links */
-    if(query_formats(graph))
-        return -1;
+    int i, reduced;
 
-    /* Once everything is merged, it's possible that we'll still have
-     * multiple valid colorspace choices. We pick the first one. */
-    pick_formats(graph);
+    do {
+        reduced = 0;
 
-    return 0;
+        for (i = 0; i < graph->nb_filters; i++)
+            reduced |= reduce_formats_on_filter(graph->filters[i]);
+    } while (reduced);
 }
 
-static int create_filter(AVFilterGraph *ctx, int index, char *name,
-                         char *args)
+static void swap_samplerates_on_filter(AVFilterContext *filter)
 {
-    AVFilterContext *filt;
+    AVFilterLink *link = NULL;
+    int sample_rate;
+    int i, j;
 
-    AVFilter *filterdef;
-    char tmp[20];
+    for (i = 0; i < filter->nb_inputs; i++) {
+        link = filter->inputs[i];
 
-    snprintf(tmp, 20, "%d", index);
-    if(!(filterdef = avfilter_get_by_name(name)) ||
-       !(filt = avfilter_open(filterdef, tmp))) {
-        av_log(&log_ctx, AV_LOG_ERROR,
-               "error creating filter '%s'\n", name);
-        return -1;
-    }
-    avfilter_graph_add_filter(ctx, filt);
-    if(avfilter_init_filter(filt, args, NULL)) {
-        av_log(&log_ctx, AV_LOG_ERROR,
-               "error initializing filter '%s'\n", name);
-        return -1;
+        if (link->type == AVMEDIA_TYPE_AUDIO &&
+            link->out_samplerates->format_count == 1)
+            break;
     }
+    if (i == filter->nb_inputs)
+        return;
 
-    return 0;
-}
+    sample_rate = link->out_samplerates->formats[0];
 
-static int link_filter(AVFilterGraph *ctx, int src, int srcpad,
-                       int dst, int dstpad)
-{
-    AVFilterContext *filt, *filtb;
+    for (i = 0; i < filter->nb_outputs; i++) {
+        AVFilterLink *outlink = filter->outputs[i];
+        int best_idx, best_diff = INT_MAX;
 
-    char tmp[20];
+        if (outlink->type != AVMEDIA_TYPE_AUDIO ||
+            outlink->in_samplerates->format_count < 2)
+            continue;
 
-    snprintf(tmp, 20, "%d", src);
-    if(!(filt = avfilter_graph_get_filter(ctx, tmp))) {
-        av_log(&log_ctx, AV_LOG_ERROR, "link source does not exist in graph\n");
-        return -1;
-    }
-    snprintf(tmp, 20, "%d", dst);
-    if(!(filtb = avfilter_graph_get_filter(ctx, tmp))) {
-        av_log(&log_ctx, AV_LOG_ERROR, "link destination does not exist in graph\n");
-        return -1;
-    }
-    if(avfilter_link(filt, srcpad, filtb, dstpad)) {
-        av_log(&log_ctx, AV_LOG_ERROR, "cannot create link between source and destination filters\n");
-        return -1;
-    }
+        for (j = 0; j < outlink->in_samplerates->format_count; j++) {
+            int diff = abs(sample_rate - outlink->in_samplerates->formats[j]);
 
-    return 0;
+            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 consume_whitespace(const char **buf)
+static void swap_samplerates(AVFilterGraph *graph)
 {
-    *buf += strspn(*buf, " \n\t");
+    int i;
+
+    for (i = 0; i < graph->nb_filters; i++)
+        swap_samplerates_on_filter(graph->filters[i]);
 }
 
-/**
- * get the next non-whitespace char
- */
-static char consume_char(const char **buf)
+#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)
 {
-    char out;
-    consume_whitespace(buf);
+    AVFilterLink *link = NULL;
+    int i, j, k;
 
-    out = **buf;
+    for (i = 0; i < filter->nb_inputs; i++) {
+        link = filter->inputs[i];
 
-    if (out)
-        (*buf)++;
+        if (link->type == AVMEDIA_TYPE_AUDIO &&
+            link->out_channel_layouts->nb_channel_layouts == 1)
+            break;
+    }
+    if (i == filter->nb_inputs)
+        return;
 
-    return out;
-}
+    for (i = 0; i < filter->nb_outputs; i++) {
+        AVFilterLink *outlink = filter->outputs[i];
+        int best_idx = -1, 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;
+                }
+            }
 
-/**
- * remove the quotation marks from a string. Ex: "aaa'bb'cc" -> "aaabbcc"
- */
-static void unquote(char *str)
-{
-    char *p1, *p2;
-    p1=p2=str;
-    while (*p1 != 0) {
-        if (*p1 != '\'')
-            *p2++ = *p1;
-        p1++;
+            /* 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;
+            }
+        }
+        av_assert0(best_idx >= 0);
+        FFSWAP(uint64_t, outlink->in_channel_layouts->channel_layouts[0],
+               outlink->in_channel_layouts->channel_layouts[best_idx]);
     }
 
-    *p2 = 0;
 }
 
-/**
- * Consumes a string from *buf.
- * @return a copy of the consumed string, which should be free'd after use
- */
-static char *consume_string(const char **buf)
+static void swap_channel_layouts(AVFilterGraph *graph)
 {
-    const char *start;
-    char *ret;
-    int size;
-
-    consume_whitespace(buf);
+    int i;
 
-    if (!(**buf))
-        return av_mallocz(1);
+    for (i = 0; i < graph->nb_filters; i++)
+        swap_channel_layouts_on_filter(graph->filters[i]);
+}
 
-    start = *buf;
+static void swap_sample_fmts_on_filter(AVFilterContext *filter)
+{
+    AVFilterLink *link = NULL;
+    int format, bps;
+    int i, j;
 
-    *buf += strcspn(*buf, " ()=,'");
+    for (i = 0; i < filter->nb_inputs; i++) {
+        link = filter->inputs[i];
 
-    if (**buf == '\'') {
-        char *p = strchr(*buf + 1, '\'');
-        if (p)
-            *buf = p + 1;
-        else
-            *buf += strlen(*buf); // Move the pointer to the null end byte
+        if (link->type == AVMEDIA_TYPE_AUDIO &&
+            link->out_formats->format_count == 1)
+            break;
     }
+    if (i == filter->nb_inputs)
+        return;
 
-    size = *buf - start + 1;
-    ret = av_malloc(size);
-    memcpy(ret, start, size - 1);
-    ret[size-1] = 0;
-
-    unquote(ret);
+    format = link->out_formats->formats[0];
+    bps    = av_get_bytes_per_sample(format);
 
-    return ret;
-}
+    for (i = 0; i < filter->nb_outputs; i++) {
+        AVFilterLink *outlink = filter->outputs[i];
+        int best_idx = -1, best_score = INT_MIN;
 
-/**
- * Parse "(linkname)"
- * @arg name a pointer (that need to be free'd after use) to the name between
- *           parenthesis
- */
-static void parse_link_name(const char **buf, char **name)
-{
-    consume_char(buf);
+        if (outlink->type != AVMEDIA_TYPE_AUDIO ||
+            outlink->in_formats->format_count < 2)
+            continue;
 
-    *name = consume_string(buf);
+        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 (!*name[0])
-        goto fail;
+            if (av_get_packed_sample_fmt(out_format) == format ||
+                av_get_planar_sample_fmt(out_format) == format) {
+                best_idx   = j;
+                break;
+            }
 
-    if (consume_char(buf) != ')')
-        goto fail;
+            /* for s32 and float prefer double to prevent loss of information */
+            if (bps == 4 && out_bps == 8) {
+                best_idx = j;
+                break;
+            }
 
-    return;
- fail:
-    av_freep(name);
-    av_log(&log_ctx, AV_LOG_ERROR, "Could not parse link name!\n");
-}
+            /* prefer closest higher or equal bps */
+            score = -abs(out_bps - bps);
+            if (out_bps >= bps)
+                score += INT_MAX/2;
 
-/**
- * Parse "filter=params"
- * @arg name a pointer (that need to be free'd after use) to the name of the
- *           filter
- * @arg ars  a pointer (that need to be free'd after use) to the args of the
- *           filter
- */
-static int parse_filter(const char **buf, AVFilterGraph *graph, int index)
-{
-    char *name, *opts;
-    name = consume_string(buf);
-
-    if (**buf == '=') {
-        consume_char(buf);
-        opts = consume_string(buf);
-    } else {
-        opts = NULL;
+            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]);
     }
-
-    return create_filter(graph, index, name, opts);
 }
 
-enum LinkType {
-    LinkTypeIn,
-    LinkTypeOut,
-};
-
-/**
- * A linked-list of the inputs/outputs of the filter chain.
- */
-typedef struct AVFilterInOut {
-    enum LinkType type;
-    char *name;
-    int instance;
-    int pad_idx;
+static void swap_sample_fmts(AVFilterGraph *graph)
+{
+    int i;
 
-    struct AVFilterInOut *next;
-} AVFilterInOut;
+    for (i = 0; i < graph->nb_filters; i++)
+        swap_sample_fmts_on_filter(graph->filters[i]);
 
-static void free_inout(AVFilterInOut *head)
-{
-    while (head) {
-        AVFilterInOut *next;
-        next = head->next;
-        av_free(head);
-        head = next;
-    }
 }
 
-/**
- * Parse "(a1)(link2) ... (etc)"
- */
-static int parse_inouts(const char **buf, AVFilterInOut **inout, int firstpad,
-                        enum LinkType type, int instance)
+static int pick_formats(AVFilterGraph *graph)
 {
-    int pad = firstpad;
-    while (**buf == '(') {
-        AVFilterInOut *inoutn = av_malloc(sizeof(AVFilterInOut));
-        parse_link_name(buf, &inoutn->name);
-        inoutn->type = type;
-        inoutn->instance = instance;
-        inoutn->pad_idx = pad++;
-        inoutn->next = *inout;
-        *inout = inoutn;
+    int i, j, ret;
+
+    for (i = 0; i < graph->nb_filters; i++) {
+        AVFilterContext *filter = graph->filters[i];
+
+        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 pad;
+    return 0;
 }
 
 /**
- * Parse a string describing a filter graph.
+ * Configure the formats of all the links in the graph.
  */
-int avfilter_graph_parse_chain(AVFilterGraph *graph, const char *filters, AVFilterContext *in, int inpad, AVFilterContext *out, int outpad)
+static int graph_config_formats(AVFilterGraph *graph, AVClass *log_ctx)
 {
-    AVFilterInOut           *inout=NULL;
-    AVFilterInOut           *head=NULL;
-
-    int index = 0;
-    char chr = 0;
-    int pad = 0;
-    int has_out = 0;
+    int ret;
 
-    char tmp[20];
-    AVFilterContext *filt;
-
-    consume_whitespace(&filters);
+    /* find supported formats from sub-filters, and merge along links */
+    if ((ret = query_formats(graph, log_ctx)) < 0)
+        return ret;
 
-    do {
-        int oldpad = pad;
+    /* Once everything is merged, it's possible that we'll still have
+     * multiple valid media format choices. We try to minimize the amount
+     * of format conversion inside filters */
+    reduce_formats(graph);
 
-        pad = parse_inouts(&filters, &inout, chr == ',', LinkTypeIn, index);
+    /* 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 (parse_filter(&filters, graph, index) < 0)
-            goto fail;
+    if ((ret = pick_formats(graph)) < 0)
+        return ret;
 
-        // If the first filter has an input and none was given, it is
-        // implicitly the input of the whole graph.
-        if (pad == 0 && graph->filters[graph->filter_count-1]->input_count == 1) {
-            snprintf(tmp, 20, "%d", index);
-            if(!(filt = avfilter_graph_get_filter(graph, tmp))) {
-                av_log(&log_ctx, AV_LOG_ERROR, "filter owning exported pad does not exist\n");
-                goto fail;
-            }
-            if(avfilter_link(in, inpad, filt, 0)) {
-                av_log(&log_ctx, AV_LOG_ERROR, "cannot create link between source and destination filters\n");
-                goto fail;
-            }
-        }
+    return 0;
+}
 
-        if(chr == ',') {
-            if (link_filter(graph, index-1, oldpad, index, 0) < 0)
-                goto fail;
+static int graph_insert_fifos(AVFilterGraph *graph, AVClass *log_ctx)
+{
+    AVFilterContext *f;
+    int i, j, ret;
+    int fifo_count = 0;
 
-        }
-        pad = parse_inouts(&filters, &inout, 0, LinkTypeOut, index);
-        chr = consume_char(&filters);
-        index++;
-    } while (chr == ',' || chr == ';');
-
-    head = inout;
-    for (; inout != NULL; inout = inout->next) {
-        if (inout->instance == -1)
-            continue; // Already processed
-
-        if (!strcmp(inout->name, "in")) {
-            snprintf(tmp, 20, "%d", inout->instance);
-            if(!(filt = avfilter_graph_get_filter(graph, tmp))) {
-                av_log(&log_ctx, AV_LOG_ERROR, "filter owning exported pad does not exist\n");
-                goto fail;
-            }
-            if(avfilter_link(in, inpad, filt, inout->pad_idx)) {
-                av_log(&log_ctx, AV_LOG_ERROR, "cannot create link between source and destination filters\n");
-                goto fail;
-            }
-        } else if (!strcmp(inout->name, "out")) {
-            has_out = 1;
-            snprintf(tmp, 20, "%d", inout->instance);
-            if(!(filt = avfilter_graph_get_filter(graph, tmp))) {
-                av_log(&log_ctx, AV_LOG_ERROR, "filter owning exported pad does not exist\n");
-                goto fail;
-            }
+    for (i = 0; i < graph->nb_filters; i++) {
+        f = graph->filters[i];
 
-            if(avfilter_link(filt, inout->pad_idx, out, outpad)) {
-                av_log(&log_ctx, AV_LOG_ERROR, "cannot create link between source and destination filters\n");
-                goto fail;
-        }
+        for (j = 0; j < f->nb_inputs; j++) {
+            AVFilterLink *link = f->inputs[j];
+            AVFilterContext *fifo_ctx;
+            AVFilter *fifo;
+            char name[32];
 
-        } else {
-            AVFilterInOut *p, *src, *dst;
-            for (p = inout->next;
-                 p && strcmp(p->name,inout->name); p = p->next);
+            if (!link->dstpad->needs_fifo)
+                continue;
 
-            if (!p) {
-                av_log(&log_ctx, AV_LOG_ERROR, "Unmatched link: %s.\n",
-                       inout->name);
-                goto fail;
-            }
+            fifo = f->inputs[j]->type == AVMEDIA_TYPE_VIDEO ?
+                   avfilter_get_by_name("fifo") :
+                   avfilter_get_by_name("afifo");
 
-            if (p->type == LinkTypeIn && inout->type == LinkTypeOut) {
-                src = inout;
-                dst = p;
-            } else if (p->type == LinkTypeOut && inout->type == LinkTypeIn) {
-                src = p;
-                dst = inout;
-            } else {
-                av_log(&log_ctx, AV_LOG_ERROR, "Two links named '%s' are either both input or both output\n",
-                       inout->name);
-                goto fail;
-            }
+            snprintf(name, sizeof(name), "auto-inserted fifo %d", fifo_count++);
 
-            if (link_filter(graph, src->instance, src->pad_idx, dst->instance, dst->pad_idx) < 0)
-                goto fail;
+            ret = avfilter_graph_create_filter(&fifo_ctx, fifo, name, NULL,
+                                               NULL, graph);
+            if (ret < 0)
+                return ret;
 
-            src->instance = -1;
-            dst->instance = -1;
+            ret = avfilter_insert_filter(link, fifo_ctx, 0, 0);
+            if (ret < 0)
+                return ret;
         }
     }
 
-    free_inout(head);
-
-    if (!has_out) {
-        snprintf(tmp, 20, "%d", index-1);
-        if(!(filt = avfilter_graph_get_filter(graph, tmp))) {
-            av_log(&log_ctx, AV_LOG_ERROR, "filter owning exported pad does not exist\n");
-            goto fail;
-        }
+    return 0;
+}
 
-        if(avfilter_link(filt, pad, out, outpad)) {
-            av_log(&log_ctx, AV_LOG_ERROR, "cannot create link between source and destination filters\n");
-            goto fail;
-        }
+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;
-
- fail:
-    free_inout(head);
-    avfilter_destroy_graph(graph);
-    return -1;
 }