lavc/qsvenc: expose low_power as a common option for QSV encoder

Always exposes low_power option for all qsv encoder, and reports a warning
if VDENC is not supported in current version of MSDK.
Signed-off-by: Linjie Fu <linjie.fu@intel.com>
Signed-off-by: Zhong Li <zhong.li@intel.com>

libavcodec/qsvenc.c

@@ -488,9 +488,18 @@ static int init_video_param(AVCodecContext *avctx, QSVEncContext *q)
         }
     }
 
+    if (q->low_power) {
 #if QSV_HAVE_VDENC
-    q->param.mfx.LowPower           = q->low_power ? MFX_CODINGOPTION_ON : MFX_CODINGOPTION_OFF;
+        q->param.mfx.LowPower = MFX_CODINGOPTION_ON;
+#else
+        av_log(avctx, AV_LOG_WARNING, "The low_power option is "
+                            "not supported with this MSDK version.\n");
+        q->low_power = 0;
+        q->param.mfx.LowPower = MFX_CODINGOPTION_OFF;
 #endif
+    } else
+        q->param.mfx.LowPower = MFX_CODINGOPTION_OFF;
+
     q->param.mfx.CodecProfile       = q->profile;
     q->param.mfx.TargetUsage        = avctx->compression_level;
     q->param.mfx.GopPicSize         = FFMAX(0, avctx->gop_size);

libavcodec/qsvenc.h

@@ -89,6 +89,7 @@
 { "adaptive_b",     "Adaptive B-frame placement",             OFFSET(qsv.adaptive_b),     AV_OPT_TYPE_INT, { .i64 = -1 }, -1,          1, VE },                         \
 { "b_strategy",     "Strategy to choose between I/P/B-frames", OFFSET(qsv.b_strategy),    AV_OPT_TYPE_INT, { .i64 = -1 }, -1,          1, VE },                         \
 { "forced_idr",     "Forcing I frames as IDR frames",         OFFSET(qsv.forced_idr),     AV_OPT_TYPE_BOOL,{ .i64 = 0  },  0,          1, VE },                         \
+{ "low_power", "enable low power mode(experimental: many limitations by mfx version, BRC modes, etc.)", OFFSET(qsv.low_power), AV_OPT_TYPE_BOOL, { .i64 = 0}, 0, 1, VE},\
 
 typedef int SetEncodeCtrlCB (AVCodecContext *avctx,
                              const AVFrame *frame, mfxEncodeCtrl* enc_ctrl);

libavcodec/qsvenc_h264.c

@@ -148,10 +148,6 @@ static const AVOption options[] = {
     { "auto"   , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = MFX_MF_AUTO     }, INT_MIN, INT_MAX,     VE, "mfmode" },
 #endif
 
-#if QSV_HAVE_VDENC
-    { "low_power", "enable low power mode(experimental: many limitations by mfx version, BRC modes, etc.)", OFFSET(qsv.low_power), AV_OPT_TYPE_BOOL, { .i64 =  0 }, 0, 1, VE},
-#endif
-
     { "repeat_pps", "repeat pps for every frame", OFFSET(qsv.repeat_pps), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VE },
 
     { NULL },