lavfi: add types and functions for channel layout/samplerate negotiation

libavfilter/avfilter.h

@@ -618,6 +618,22 @@ struct AVFilterLink {
      * input link is assumed to be an unchangeable property.
      */
     AVRational time_base;
+
+    /*****************************************************************
+     * All fields below this line are not part of the public API. They
+     * may not be used outside of libavfilter and can be changed and
+     * removed at will.
+     * New public fields should be added right above.
+     *****************************************************************
+     */
+    /**
+     * Lists of channel layouts and sample rates used for automatic
+     * negotiation.
+     */
+    AVFilterFormats  *in_samplerates;
+    AVFilterFormats *out_samplerates;
+    struct AVFilterChannelLayouts  *in_channel_layouts;
+    struct AVFilterChannelLayouts *out_channel_layouts;
 };
 
 /**

libavfilter/formats.h

+/*
+ * This file is part of Libav.
+ *
+ * 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.
+ *
+ * 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVFILTER_FORMATS_H
+#define AVFILTER_FORMATS_H
+
+#include "avfilter.h"
+
+typedef struct AVFilterChannelLayouts {
+    uint64_t *channel_layouts;  ///< list of channel layouts
+    int    nb_channel_layouts;  ///< number of channel layouts
+
+    unsigned refcount;          ///< number of references to this list
+    struct AVFilterChannelLayouts ***refs; ///< references to this list
+} AVFilterChannelLayouts;
+
+/**
+ * Return a channel layouts/samplerates list which contains the intersection of
+ * the layouts/samplerates of a and b. Also, all the references of a, all the
+ * references of b, and a and b themselves will be deallocated.
+ *
+ * If a and b do not share any common elements, neither is modified, and NULL
+ * is returned.
+ */
+AVFilterChannelLayouts *ff_merge_channel_layouts(AVFilterChannelLayouts *a,
+                                                 AVFilterChannelLayouts *b);
+AVFilterFormats *ff_merge_samplerates(AVFilterFormats *a,
+                                      AVFilterFormats *b);
+
+/**
+ * Construct an empty AVFilterChannelLayouts/AVFilterFormats struct --
+ * representing any channel layout/sample rate.
+ */
+AVFilterChannelLayouts *ff_all_channel_layouts(void);
+AVFilterFormats *ff_all_samplerates(void);
+
+/**
+ * A helper for query_formats() which sets all links to the same list of channel
+ * layouts/sample rates. If there are no links hooked to this filter, the list
+ * is freed.
+ */
+void ff_set_common_channel_layouts(AVFilterContext *ctx,
+                                   AVFilterChannelLayouts *layouts);
+void ff_set_common_samplerates(AVFilterContext *ctx,
+                               AVFilterFormats *samplerates);
+
+int ff_add_channel_layout(AVFilterChannelLayouts **l, uint64_t channel_layout);
+
+/**
+ * Add *ref as a new reference to f.
+ */
+void ff_channel_layouts_ref(AVFilterChannelLayouts *f,
+                            AVFilterChannelLayouts **ref);
+
+/**
+ * Remove a reference to a channel layouts list.
+ */
+void ff_channel_layouts_unref(AVFilterChannelLayouts **ref);
+
+void ff_channel_layouts_changeref(AVFilterChannelLayouts **oldref,
+                                  AVFilterChannelLayouts **newref);
+
+#endif // AVFILTER_FORMATS_H