avfilter/avfiltergraph: add an "auto" constant to the threads option

Signed-off-by: James Almer <jamrial@gmail.com>

libavfilter/avfiltergraph.c

@@ -50,8 +50,9 @@ static const AVOption filtergraph_options[] = {
     { "thread_type", "Allowed thread types", OFFSET(thread_type), AV_OPT_TYPE_FLAGS,
         { .i64 = AVFILTER_THREAD_SLICE }, 0, INT_MAX, F|V|A, "thread_type" },
         { "slice", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AVFILTER_THREAD_SLICE }, .flags = F|V|A, .unit = "thread_type" },
-    { "threads",     "Maximum number of threads", OFFSET(nb_threads),
+    { "threads",     "Maximum number of threads", OFFSET(nb_threads), AV_OPT_TYPE_INT,
-        AV_OPT_TYPE_INT,   { .i64 = 0 }, 0, INT_MAX, F|V|A },
+        { .i64 = 0 }, 0, INT_MAX, F|V|A, "threads"},
+        {"auto", "autodetect a suitable number of threads to use", 0, AV_OPT_TYPE_CONST, {.i64 = 0 }, .flags = F|V|A, .unit = "threads"},
     {"scale_sws_opts"       , "default scale filter options"        , OFFSET(scale_sws_opts)        ,
         AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, F|V },
     {"aresample_swr_opts"   , "default aresample filter options"    , OFFSET(aresample_swr_opts)    ,

libavfilter/version.h

@@ -31,7 +31,7 @@
 
 #define LIBAVFILTER_VERSION_MAJOR   8
 #define LIBAVFILTER_VERSION_MINOR   7
-#define LIBAVFILTER_VERSION_MICRO 100
+#define LIBAVFILTER_VERSION_MICRO 101
 
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \