lavfi/af_amix: make sure the output does not depend on input ordering

Signed-off-by: Anton Khirnov <anton@khirnov.net>

libavfilter/af_amix.c

@@ -394,6 +394,8 @@ static int request_samples(AVFilterContext *ctx, int min_samples)
     int i;
 
     av_assert0(s->nb_inputs > 1);
+    if (min_samples == 1 && s->duration_mode == DURATION_FIRST)
+        min_samples = av_audio_fifo_size(s->fifos[0]);
 
     for (i = 1; i < s->nb_inputs; i++) {
         if (!(s->input_state[i] & INPUT_ON) ||
@@ -402,6 +404,7 @@ static int request_samples(AVFilterContext *ctx, int min_samples)
         if (av_audio_fifo_size(s->fifos[i]) >= min_samples)
             continue;
         ff_inlink_request_frame(ctx->inputs[i]);
+        return 0;
     }
     return output_frame(ctx->outputs[0]);
 }
@@ -471,17 +474,13 @@ static int activate(AVFilterContext *ctx)
 
         if (ff_inlink_acknowledge_status(ctx->inputs[i], &status, &pts)) {
             if (status == AVERROR_EOF) {
-                if (i == 0) {
-                    s->input_state[i] = 0;
+                s->input_state[i] |= INPUT_EOF;
+                if (av_audio_fifo_size(s->fifos[i]) == 0) {
+                    s->input_state[i] &= ~INPUT_ON;
                     if (s->nb_inputs == 1) {
                         ff_outlink_set_status(outlink, status, pts);
                         return 0;
                     }
-                } else {
-                    s->input_state[i] |= INPUT_EOF;
-                    if (av_audio_fifo_size(s->fifos[i]) == 0) {
-                        s->input_state[i] = 0;
-                    }
                 }
             }
         }