libvpxenc: Allow setting tune parameter

doc/encoders.texi

@@ -1584,6 +1584,12 @@ follows: @code{(minrate * 100 / bitrate)}.
 
 @item crf (@emph{end-usage=cq}, @emph{cq-level})
 
+@item tune (@emph{tune})
+@table @samp
+@item psnr (@emph{psnr})
+@item ssim (@emph{ssim})
+@end table
+
 @item quality, deadline (@emph{deadline})
 @table @samp
 @item best

libavcodec/libvpxenc.c

@@ -88,6 +88,8 @@ typedef struct VP8EncoderContext {
     int arnr_strength;
     int arnr_type;
 
+    int tune;
+
     int lag_in_frames;
     int error_resilient;
     int crf;
@@ -116,6 +118,7 @@ static const char *const ctlidstr[] = {
     [VP8E_SET_ARNR_MAXFRAMES]    = "VP8E_SET_ARNR_MAXFRAMES",
     [VP8E_SET_ARNR_STRENGTH]     = "VP8E_SET_ARNR_STRENGTH",
     [VP8E_SET_ARNR_TYPE]         = "VP8E_SET_ARNR_TYPE",
+    [VP8E_SET_TUNING]            = "VP8E_SET_TUNING",
     [VP8E_SET_CQ_LEVEL]          = "VP8E_SET_CQ_LEVEL",
     [VP8E_SET_MAX_INTRA_BITRATE_PCT] = "VP8E_SET_MAX_INTRA_BITRATE_PCT",
 #if CONFIG_LIBVPX_VP9_ENCODER
@@ -611,6 +614,8 @@ FF_ENABLE_DEPRECATION_WARNINGS
         codecctl_int(avctx, VP8E_SET_ARNR_STRENGTH,    ctx->arnr_strength);
     if (ctx->arnr_type >= 0)
         codecctl_int(avctx, VP8E_SET_ARNR_TYPE,        ctx->arnr_type);
+    if (ctx->tune >= 0)
+        codecctl_int(avctx, VP8E_SET_TUNING,           ctx->tune);
 
     if (CONFIG_LIBVPX_VP8_ENCODER && avctx->codec_id == AV_CODEC_ID_VP8) {
 #if FF_API_PRIVATE_OPT
@@ -1010,6 +1015,9 @@ static int vp8_encode(AVCodecContext *avctx, AVPacket *pkt,
     { "backward",        NULL, 0, AV_OPT_TYPE_CONST, {.i64 = 1}, 0, 0, VE, "arnr_type" }, \
     { "forward",         NULL, 0, AV_OPT_TYPE_CONST, {.i64 = 2}, 0, 0, VE, "arnr_type" }, \
     { "centered",        NULL, 0, AV_OPT_TYPE_CONST, {.i64 = 3}, 0, 0, VE, "arnr_type" }, \
+    { "tune",            "Tune the encoding to a specific scenario", OFFSET(tune),          AV_OPT_TYPE_INT, {.i64 = -1},      -1,      INT_MAX, VE, "tune"}, \
+    { "psnr",            NULL, 0, AV_OPT_TYPE_CONST, {.i64 = VP8_TUNE_PSNR}, 0, 0, VE, "tune"}, \
+    { "ssim",            NULL, 0, AV_OPT_TYPE_CONST, {.i64 = VP8_TUNE_SSIM}, 0, 0, VE, "tune"}, \
     { "deadline",        "Time to spend encoding, in microseconds.", OFFSET(deadline),      AV_OPT_TYPE_INT, {.i64 = VPX_DL_GOOD_QUALITY}, INT_MIN, INT_MAX, VE, "quality"}, \
     { "best",            NULL, 0, AV_OPT_TYPE_CONST, {.i64 = VPX_DL_BEST_QUALITY}, 0, 0, VE, "quality"}, \
     { "good",            NULL, 0, AV_OPT_TYPE_CONST, {.i64 = VPX_DL_GOOD_QUALITY}, 0, 0, VE, "quality"}, \