avformat/apng: set max_fps to no limit by default

Should fix ticket #6252
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: James Almer <jamrial@gmail.com>

libavformat/apngdec.c

@@ -421,7 +421,7 @@ static const AVOption options[] = {
     { "ignore_loop", "ignore loop setting"                         , offsetof(APNGDemuxContext, ignore_loop),
       AV_OPT_TYPE_BOOL, { .i64 = 1 }              , 0, 1      , AV_OPT_FLAG_DECODING_PARAM },
     { "max_fps"    , "maximum framerate (0 is no limit)"           , offsetof(APNGDemuxContext, max_fps),
-      AV_OPT_TYPE_INT, { .i64 = DEFAULT_APNG_FPS }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
+      AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
     { "default_fps", "default framerate (0 is as fast as possible)", offsetof(APNGDemuxContext, default_fps),
       AV_OPT_TYPE_INT, { .i64 = DEFAULT_APNG_FPS }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
     { NULL },