avcodec/qsv : Added look ahead rate control mode

Reviewed-by: Ivan Uskov <ivan.uskov@nablet.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/qsvenc.c

@@ -107,8 +107,16 @@ static int init_video_param(AVCodecContext *avctx, QSVEncContext *q)
         q->param.mfx.RateControlMethod = MFX_RATECONTROL_CBR;
         ratecontrol_desc = "constant bitrate (CBR)";
     } else if (!avctx->rc_max_rate) {
-        q->param.mfx.RateControlMethod = MFX_RATECONTROL_AVBR;
-        ratecontrol_desc = "average variable bitrate (AVBR)";
+#if QSV_VERSION_ATLEAST(1,7)
+        if (q->look_ahead) {
+            q->param.mfx.RateControlMethod = MFX_RATECONTROL_LA;
+            ratecontrol_desc = "lookahead (LA)";
+        } else
+#endif
+        {
+            q->param.mfx.RateControlMethod = MFX_RATECONTROL_AVBR;
+            ratecontrol_desc = "average variable bitrate (AVBR)";
+        }
     } else {
         q->param.mfx.RateControlMethod = MFX_RATECONTROL_VBR;
         ratecontrol_desc = "variable bitrate (VBR)";
@@ -132,6 +140,9 @@ static int init_video_param(AVCodecContext *avctx, QSVEncContext *q)
 
         break;
     case MFX_RATECONTROL_AVBR:
+#if QSV_VERSION_ATLEAST(1,7)
+    case MFX_RATECONTROL_LA:
+#endif
         q->param.mfx.TargetKbps  = avctx->bit_rate / 1000;
         q->param.mfx.Convergence = q->avbr_convergence;
         q->param.mfx.Accuracy    = q->avbr_accuracy;
@@ -151,6 +162,22 @@ static int init_video_param(AVCodecContext *avctx, QSVEncContext *q)
 
         q->extparam[0] = (mfxExtBuffer *)&q->extco;
 
+#if QSV_VERSION_ATLEAST(1,6)
+        q->extco2.Header.BufferId      = MFX_EXTBUFF_CODING_OPTION2;
+        q->extco2.Header.BufferSz      = sizeof(q->extco2);
+
+#if QSV_VERSION_ATLEAST(1,7)
+        // valid value range is from 10 to 100 inclusive
+        // to instruct the encoder to use the default value this should be set to zero
+        q->extco2.LookAheadDepth        = q->look_ahead_depth != 0 ? FFMAX(10, q->look_ahead_depth) : 0;
+#endif
+#if QSV_VERSION_ATLEAST(1,8)
+        q->extco2.LookAheadDS           = q->look_ahead_downsampling;
+#endif
+
+        q->extparam[1] = (mfxExtBuffer *)&q->extco2;
+
+#endif
         q->param.ExtParam    = q->extparam;
         q->param.NumExtParam = FF_ARRAY_ELEMS(q->extparam);
     }

libavcodec/qsvenc.h

@@ -50,7 +50,12 @@ typedef struct QSVEncContext {
     mfxFrameAllocRequest req;
 
     mfxExtCodingOption  extco;
+#if QSV_VERSION_ATLEAST(1,6)
+    mfxExtCodingOption2 extco2;
+    mfxExtBuffer *extparam[2];
+#else
     mfxExtBuffer *extparam[1];
+#endif
 
     AVFifoBuffer *async_fifo;
 
@@ -62,6 +67,9 @@ typedef struct QSVEncContext {
     int avbr_accuracy;
     int avbr_convergence;
     int pic_timing_sei;
+    int look_ahead;
+    int look_ahead_depth;
+    int look_ahead_downsampling;
 
     char *load_plugins;
 } QSVEncContext;

libavcodec/qsvenc_h264.c

@@ -71,6 +71,18 @@ static const AVOption options[] = {
     { "avbr_convergence", "Convergence of the AVBR ratecontrol", OFFSET(qsv.avbr_convergence), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, VE },
     { "pic_timing_sei",    "Insert picture timing SEI with pic_struct_syntax element", OFFSET(qsv.pic_timing_sei), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, VE },
 
+#if QSV_VERSION_ATLEAST(1,7)
+    { "look_ahead",       "Use VBR algorithm with look ahead",    OFFSET(qsv.look_ahead),       AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, VE },
+    { "look_ahead_depth", "Depth of look ahead in number frames", OFFSET(qsv.look_ahead_depth), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 100, VE },
+#endif
+
+#if QSV_VERSION_ATLEAST(1,8)
+    { "look_ahead_downsampling", NULL, OFFSET(qsv.look_ahead_downsampling), AV_OPT_TYPE_INT, { .i64 = MFX_LOOKAHEAD_DS_UNKNOWN }, MFX_LOOKAHEAD_DS_UNKNOWN, MFX_LOOKAHEAD_DS_2x, VE, "look_ahead_downsampling" },
+    { "unknown"                , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = MFX_LOOKAHEAD_DS_UNKNOWN }, INT_MIN, INT_MAX,     VE, "look_ahead_downsampling" },
+    { "off"                    , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = MFX_LOOKAHEAD_DS_OFF     }, INT_MIN, INT_MAX,     VE, "look_ahead_downsampling" },
+    { "2x"                     , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = MFX_LOOKAHEAD_DS_2x      }, INT_MIN, INT_MAX,     VE, "look_ahead_downsampling" },
+#endif
+
     { "profile", NULL, OFFSET(qsv.profile), AV_OPT_TYPE_INT, { .i64 = MFX_PROFILE_UNKNOWN }, 0, INT_MAX, VE, "profile" },
     { "unknown" , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = MFX_PROFILE_UNKNOWN      }, INT_MIN, INT_MAX,     VE, "profile" },
     { "baseline", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = MFX_PROFILE_AVC_BASELINE }, INT_MIN, INT_MAX,     VE, "profile" },