+ { "data_field", "select data field", OFFSET(data_field), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 1, SD, "data_field" },
+ { "auto", "pick first one that appears", 0, AV_OPT_TYPE_CONST, { .i64 =-1 }, 0, 0, SD, "data_field" },
+ { "first", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 0 }, 0, 0, SD, "data_field" },
+ { "second", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 1 }, 0, 0, SD, "data_field" },