vp9 encoder: use a decent default speed setting

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

libavcodec/libvpxenc.c

@@ -541,7 +541,7 @@ static int vp8_encode(AVCodecContext *avctx, AVPacket *pkt,
 #define OFFSET(x) offsetof(VP8Context, x)
 #define VE AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
 static const AVOption options[] = {
-    { "cpu-used",        "Quality/Speed ratio modifier",           OFFSET(cpu_used),        AV_OPT_TYPE_INT, {.i64 = INT_MIN}, INT_MIN, INT_MAX, VE},
+    { "cpu-used",        "Quality/Speed ratio modifier",           OFFSET(cpu_used),        AV_OPT_TYPE_INT, {.i64 = 1}, INT_MIN, INT_MAX, VE},
     { "auto-alt-ref",    "Enable use of alternate reference "
                          "frames (2-pass only)",                   OFFSET(auto_alt_ref),    AV_OPT_TYPE_INT, {.i64 = -1},      -1,      1,       VE},
     { "lag-in-frames",   "Number of frames to look ahead for "