libx264: fix setting some options.

Specifically: gop_size, max_b_frames, scenechange_threshold, qmin, qmax,
max_qdiff, qblur, qcompress and refs.

Change their default values to -1 and only use them if the user
explicitly set them. Otherwise x264 defaults are used.

Move setting those options after x264_param_default_preset(), so they
don't get overwritten by it.

libavcodec/libx264.c

@@ -189,9 +189,6 @@ static av_cold int X264_init(AVCodecContext *avctx)
 
     x264_param_default(&x4->params);
 
-    x4->params.i_keyint_max         = avctx->gop_size;
-
-    x4->params.i_bframe          = avctx->max_b_frames;
     x4->params.b_cabac           = avctx->coder_type == FF_CODER_TYPE_AC;
     x4->params.i_bframe_adaptive = avctx->b_frame_strategy;
     x4->params.i_bframe_bias     = avctx->bframebias;
@@ -200,22 +197,12 @@ static av_cold int X264_init(AVCodecContext *avctx)
     if (x4->params.i_keyint_min > x4->params.i_keyint_max)
         x4->params.i_keyint_min = x4->params.i_keyint_max;
 
-    x4->params.i_scenecut_threshold        = avctx->scenechange_threshold;
-
     x4->params.b_deblocking_filter         = avctx->flags & CODEC_FLAG_LOOP_FILTER;
     x4->params.i_deblocking_filter_alphac0 = avctx->deblockalpha;
     x4->params.i_deblocking_filter_beta    = avctx->deblockbeta;
 
-    x4->params.rc.i_qp_min                 = avctx->qmin;
-    x4->params.rc.i_qp_max                 = avctx->qmax;
-    x4->params.rc.i_qp_step                = avctx->max_qdiff;
-
-    x4->params.rc.f_qcompress       = avctx->qcompress; /* 0.0 => cbr, 1.0 => constant qp */
-    x4->params.rc.f_qblur           = avctx->qblur;     /* temporally blur quants */
     x4->params.rc.f_complexity_blur = avctx->complexityblur;
 
-    x4->params.i_frame_reference    = avctx->refs;
-
     x4->params.analyse.inter    = 0;
     if (avctx->partitions) {
         if (avctx->partitions & X264_PART_I4X4)
@@ -333,6 +320,25 @@ static av_cold int X264_init(AVCodecContext *avctx)
     x4->params.rc.b_mb_tree               = !!(avctx->flags2 & CODEC_FLAG2_MBTREE);
 #endif
 
+    if (avctx->gop_size >= 0)
+        x4->params.i_keyint_max         = avctx->gop_size;
+    if (avctx->max_b_frames >= 0)
+        x4->params.i_bframe             = avctx->max_b_frames;
+    if (avctx->scenechange_threshold >= 0)
+        x4->params.i_scenecut_threshold = avctx->scenechange_threshold;
+    if (avctx->qmin >= 0)
+        x4->params.rc.i_qp_min          = avctx->qmin;
+    if (avctx->qmax >= 0)
+        x4->params.rc.i_qp_max          = avctx->qmax;
+    if (avctx->max_qdiff >= 0)
+        x4->params.rc.i_qp_step         = avctx->max_qdiff;
+    if (avctx->qblur >= 0)
+        x4->params.rc.f_qblur           = avctx->qblur;     /* temporally blur quants */
+    if (avctx->qcompress >= 0)
+        x4->params.rc.f_qcompress       = avctx->qcompress; /* 0.0 => cbr, 1.0 => constant qp */
+    if (avctx->refs >= 0)
+        x4->params.i_frame_reference    = avctx->refs;
+
     if (x4->aq_mode >= 0)
         x4->params.rc.i_aq_mode = x4->aq_mode;
     if (x4->aq_strength >= 0)
@@ -475,6 +481,15 @@ static const AVClass class = {
 
 static const AVCodecDefault x264_defaults[] = {
     { "b",                "0" },
+    { "bf",               "-1" },
+    { "g",                "-1" },
+    { "qmin",             "-1" },
+    { "qmax",             "-1" },
+    { "qdiff",            "-1" },
+    { "qblur",            "-1" },
+    { "qcomp",            "-1" },
+    { "refs",             "-1" },
+    { "sc_threshold",     "-1" },
     { "threads",          AV_STRINGIFY(X264_THREADS_AUTO) },
     { NULL },
 };

libavcodec/options.c

@@ -147,11 +147,11 @@ static const AVOption options[]={
 {"frame_number", NULL, OFFSET(frame_number), FF_OPT_TYPE_INT, {.dbl = DEFAULT }, INT_MIN, INT_MAX},
 {"delay", NULL, OFFSET(delay), FF_OPT_TYPE_INT, {.dbl = DEFAULT }, INT_MIN, INT_MAX},
 {"qcomp", "video quantizer scale compression (VBR)", OFFSET(qcompress), FF_OPT_TYPE_FLOAT, {.dbl = 0.5 }, -FLT_MAX, FLT_MAX, V|E},
-{"qblur", "video quantizer scale blur (VBR)", OFFSET(qblur), FF_OPT_TYPE_FLOAT, {.dbl = 0.5 }, 0, FLT_MAX, V|E},
+{"qblur", "video quantizer scale blur (VBR)", OFFSET(qblur), FF_OPT_TYPE_FLOAT, {.dbl = 0.5 }, -1, FLT_MAX, V|E},
-{"qmin", "min video quantizer scale (VBR)", OFFSET(qmin), FF_OPT_TYPE_INT, {.dbl = 2 }, 0, 69, V|E},
+{"qmin", "min video quantizer scale (VBR)", OFFSET(qmin), FF_OPT_TYPE_INT, {.dbl = 2 }, -1, 69, V|E},
-{"qmax", "max video quantizer scale (VBR)", OFFSET(qmax), FF_OPT_TYPE_INT, {.dbl = 31 }, 0, 69, V|E},
+{"qmax", "max video quantizer scale (VBR)", OFFSET(qmax), FF_OPT_TYPE_INT, {.dbl = 31 }, -1, 69, V|E},
 {"qdiff", "max difference between the quantizer scale (VBR)", OFFSET(max_qdiff), FF_OPT_TYPE_INT, {.dbl = 3 }, INT_MIN, INT_MAX, V|E},
-{"bf", "use 'frames' B frames", OFFSET(max_b_frames), FF_OPT_TYPE_INT, {.dbl = DEFAULT }, 0, FF_MAX_B_FRAMES, V|E},
+{"bf", "use 'frames' B frames", OFFSET(max_b_frames), FF_OPT_TYPE_INT, {.dbl = DEFAULT }, -1, FF_MAX_B_FRAMES, V|E},
 {"b_qfactor", "qp factor between p and b frames", OFFSET(b_quant_factor), FF_OPT_TYPE_FLOAT, {.dbl = 1.25 }, -FLT_MAX, FLT_MAX, V|E},
 {"rc_strategy", "ratecontrol method", OFFSET(rc_strategy), FF_OPT_TYPE_INT, {.dbl = DEFAULT }, INT_MIN, INT_MAX, V|E},
 {"b_strategy", "strategy to choose between I/P/B-frames", OFFSET(b_frame_strategy), FF_OPT_TYPE_INT, {.dbl = 0 }, INT_MIN, INT_MAX, V|E},