lavf/qsv_vpp: add frame format option

1. Currently output format is hard-coded as NV12, thus means
   CSC is always done for not NV12 input such as P010.
   Follow original input format as default output.
2. Add an option to specify output format.
Signed-off-by: Zhong Li <zhong.li@intel.com>

libavfilter/vf_vpp_qsv.c

@@ -57,6 +57,10 @@ typedef struct VPPContext{
 
     int out_width;
     int out_height;
+    /**
+     * Output sw format. AV_PIX_FMT_NONE for no conversion.
+     */
+    enum AVPixelFormat out_format;
 
     AVRational framerate;       /* target framerate */
     int use_frc;                /* use framerate conversion */
@@ -79,6 +83,7 @@ typedef struct VPPContext{
 
     char *cx, *cy, *cw, *ch;
     char *ow, *oh;
+    char *output_format_str;
 } VPPContext;
 
 static const AVOption options[] = {
@@ -104,6 +109,8 @@ static const AVOption options[] = {
     { "width",  "Output video width",  OFFSET(ow), AV_OPT_TYPE_STRING, { .str="cw" }, 0, 255, .flags = FLAGS },
     { "h",      "Output video height", OFFSET(oh), AV_OPT_TYPE_STRING, { .str="w*ch/cw" }, 0, 255, .flags = FLAGS },
     { "height", "Output video height", OFFSET(oh), AV_OPT_TYPE_STRING, { .str="w*ch/cw" }, 0, 255, .flags = FLAGS },
+    { "format", "Output pixel format", OFFSET(output_format_str), AV_OPT_TYPE_STRING, { .str = "same" }, .flags = FLAGS },
+
     { NULL }
 };
 
@@ -207,6 +214,23 @@ release:
     return ret;
 }
 
+static av_cold int vpp_init(AVFilterContext *ctx)
+{
+    VPPContext  *vpp  = ctx->priv;
+
+    if (!strcmp(vpp->output_format_str, "same")) {
+        vpp->out_format = AV_PIX_FMT_NONE;
+    } else {
+        vpp->out_format = av_get_pix_fmt(vpp->output_format_str);
+        if (vpp->out_format == AV_PIX_FMT_NONE) {
+            av_log(ctx, AV_LOG_ERROR, "Unrecognized output pixel format: %s\n", vpp->output_format_str);
+            return AVERROR(EINVAL);
+        }
+    }
+
+    return 0;
+}
+
 static int config_input(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
@@ -251,6 +275,7 @@ static int config_output(AVFilterLink *outlink)
     QSVVPPCrop      crop  = { 0 };
     mfxExtBuffer    *ext_buf[ENH_FILTERS_COUNT];
     AVFilterLink    *inlink = ctx->inputs[0];
+    enum AVPixelFormat in_format;
 
     outlink->w          = vpp->out_width;
     outlink->h          = vpp->out_height;
@@ -258,10 +283,19 @@ static int config_output(AVFilterLink *outlink)
     outlink->time_base  = av_inv_q(vpp->framerate);
 
     param.filter_frame  = NULL;
-    param.out_sw_format = AV_PIX_FMT_NV12;
     param.num_ext_buf   = 0;
     param.ext_buf       = ext_buf;
 
+    if (inlink->format == AV_PIX_FMT_QSV) {
+         if (!inlink->hw_frames_ctx || !inlink->hw_frames_ctx->data)
+             return AVERROR(EINVAL);
+         else
+             in_format = ((AVHWFramesContext*)inlink->hw_frames_ctx->data)->sw_format;
+    } else
+        in_format = inlink->format;
+
+    param.out_sw_format  = (vpp->out_format == AV_PIX_FMT_NONE) ? in_format : vpp->out_format;
+
     if (vpp->use_crop) {
         crop.in_idx = 0;
         crop.x = vpp->crop_x;
@@ -422,6 +456,7 @@ AVFilter ff_vf_vpp_qsv = {
     .description   = NULL_IF_CONFIG_SMALL("Quick Sync Video VPP."),
     .priv_size     = sizeof(VPPContext),
     .query_formats = query_formats,
+    .init          = vpp_init,
     .uninit        = vpp_uninit,
     .inputs        = vpp_inputs,
     .outputs       = vpp_outputs,