avcodec/options_table: improve max/min rate help text

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/options_table.h

@@ -179,8 +179,8 @@ static const AVOption avcodec_options[] = {
           "bits2qp(bits), qp2bits(qp). Also the following constants are available: iTex pTex tex mv "
           "fCode iCount mcVar var isI isP isB avgQP qComp avgIITex avgPITex avgPPTex avgBPTex avgTex.",
           OFFSET(rc_eq), AV_OPT_TYPE_STRING, {.str = NULL}, CHAR_MIN, CHAR_MAX, V|E},
-{"maxrate", "Set maximum bitrate tolerance (in bits/s). Requires bufsize to be set.", OFFSET(rc_max_rate), AV_OPT_TYPE_INT, {.i64 = DEFAULT }, INT_MIN, INT_MAX, V|A|E},
-{"minrate", "Set minimum bitrate tolerance (in bits/s). Most useful in setting up a CBR encode. It is of little use otherwise.",
+{"maxrate", "maximum bitrate (in bits/s). Used for VBV together with bufsize.", OFFSET(rc_max_rate), AV_OPT_TYPE_INT, {.i64 = DEFAULT }, 0, INT_MAX, V|A|E},
+{"minrate", "minimum bitrate (in bits/s). Most useful in setting up a CBR encode. It is of little use otherwise.",
             OFFSET(rc_min_rate), AV_OPT_TYPE_INT, {.i64 = DEFAULT }, INT_MIN, INT_MAX, V|A|E},
 {"bufsize", "set ratecontrol buffer size (in bits)", OFFSET(rc_buffer_size), AV_OPT_TYPE_INT, {.i64 = DEFAULT }, INT_MIN, INT_MAX, A|V|E},
 {"rc_buf_aggressivity", "currently useless", OFFSET(rc_buffer_aggressivity), AV_OPT_TYPE_FLOAT, {.dbl = 1.0 }, -FLT_MAX, FLT_MAX, V|E},