lavfi: implement ff_all_channel_counts().

libavfilter/formats.c

@@ -376,6 +376,15 @@ AVFilterChannelLayouts *ff_all_channel_layouts(void)
     return ret;
 }
 
+AVFilterChannelLayouts *ff_all_channel_counts(void)
+{
+    AVFilterChannelLayouts *ret = av_mallocz(sizeof(*ret));
+    if (!ret)
+        return NULL;
+    ret->all_layouts = ret->all_counts = 1;
+    return ret;
+}
+
 #define FORMATS_REF(f, ref)                                          \
 do {                                                                 \
     *ref = f;                                                        \

libavfilter/formats.h

@@ -123,11 +123,17 @@ AVFilterFormats *ff_merge_samplerates(AVFilterFormats *a,
 
 /**
  * Construct an empty AVFilterChannelLayouts/AVFilterFormats struct --
- * representing any channel layout/sample rate.
+ * representing any channel layout (with known disposition)/sample rate.
  */
 AVFilterChannelLayouts *ff_all_channel_layouts(void);
 AVFilterFormats *ff_all_samplerates(void);
 
+/**
+ * Construct an AVFilterChannelLayouts coding for any channel layout, with
+ * known or unknown disposition.
+ */
+AVFilterChannelLayouts *ff_all_channel_counts(void);
+
 AVFilterChannelLayouts *avfilter_make_format64_list(const int64_t *fmts);