lavfi/amerge: switch to an AVOptions-based system.

doc/filters.texi

@@ -759,7 +759,7 @@ aformat=sample_fmts=u8|s16:channel_layouts=stereo
 
 Merge two or more audio streams into a single multi-channel stream.
 
-The filter accepts the following named options:
+The filter accepts the following options:
 
 @table @option
 

libavfilter/af_amerge.c

@@ -306,15 +306,8 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)
 static av_cold int init(AVFilterContext *ctx, const char *args)
 {
     AMergeContext *am = ctx->priv;
-    int ret, i;
+    int i;
 
-    am->class = &amerge_class;
-    av_opt_set_defaults(am);
-    ret = av_set_options_string(am, args, "=", ":");
-    if (ret < 0) {
-        av_log(ctx, AV_LOG_ERROR, "Error parsing options: '%s'\n", args);
-        return ret;
-    }
     am->in = av_calloc(am->nb_inputs, sizeof(*am->in));
     if (!am->in)
         return AVERROR(ENOMEM);

libavfilter/avfilter.c

@@ -674,7 +674,6 @@ static int process_options(AVFilterContext *ctx, AVDictionary **options,
 static const char *const filters_left_to_update[] = {
     "abuffer",
     "aconvert",
-    "amerge",
     "aresample",
     "atempo",
     "buffer",