lavc/qsvenc: enable hevc gpb option

GPB is the default type, just contains forward references but the
slice_type is B slice with higher encoding efficiency than regular P
slice, but lower performance.

Add an option to allow user to set regular P slice.

Fix ticket#6870

Test data on Intel Kabylake (i7-7567U CPU @ 3.50GHz):
1. ffmpeg -hwaccel qsv -c:v h264_qsv -i bbb_sunflower_1080p_30fps_normal.mp4 -vsync passthrough
-vframes 1000  -c:v hevc_qsv -gpb 0 -bf 0 -q 25 test_gpb_off_bf0_kbl.mp4

transcoding fps: 85
encoded file size of test_gpb_off_bf0_kbl.mp4: 21960100 (bytes)

2. ffmpeg -hwaccel qsv -c:v h264_qsv -i bbb_sunflower_1080p_30fps_normal.mp4 -vsync passthrough
-vframes 1000  -c:v hevc_qsv -gpb 1 -bf 0 -q 25 test_gpb_on_bf0_kbl.mp4

transcoding fps: 79
encoded file size oftest_gpb_on_bf0_kbl.mp4:  21211449 (bytes)

In this case, enable gpb can bring about 7% performance drop but 3.4% encoding efficiency improvment.

Signed-off-by: Zhong Li <zhong.li@intel.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/libavcodec/qsvenc.c b/libavcodec/qsvenc.c
index 55f1223f02..a03ab69590 100644
--- a/libavcodec/qsvenc.c
+++ b/libavcodec/qsvenc.c
@@ -267,6 +267,11 @@ static void dump_video_param(AVCodecContext *avctx, QSVEncContext *q,
 #endif
 #endif
 
+#if QSV_HAVE_GPB
+    if (avctx->codec_id == AV_CODEC_ID_HEVC)
+        av_log(avctx, AV_LOG_VERBOSE,"GPB: %s\n", print_threestate(co3->GPB));
+#endif
+
     if (avctx->codec_id == AV_CODEC_ID_H264) {
         av_log(avctx, AV_LOG_VERBOSE, "Entropy coding: %s; MaxDecFrameBuffering: %"PRIu16"\n",
                co->CAVLC == MFX_CODINGOPTION_ON ? "CAVLC" : "CABAC", co->MaxDecFrameBuffering);
@@ -748,6 +753,10 @@ FF_ENABLE_DEPRECATION_WARNINGS
 #if QSV_HAVE_CO3
         q->extco3.Header.BufferId      = MFX_EXTBUFF_CODING_OPTION3;
         q->extco3.Header.BufferSz      = sizeof(q->extco3);
+#if QSV_HAVE_GPB
+        if (avctx->codec_id == AV_CODEC_ID_HEVC)
+            q->extco3.GPB              = q->gpb ? MFX_CODINGOPTION_ON : MFX_CODINGOPTION_OFF;
+#endif
         q->extparam_internal[q->nb_extparam_internal++] = (mfxExtBuffer *)&q->extco3;
 #endif
     }