[FFmpeg-devel] [PATCH] lavfi/overlay: add process_command callback

[Stefano Sabatini]

---
 doc/filters.texi         |   14 ++++++++++++
 libavfilter/vf_overlay.c |   53 ++++++++++++++++++++++++++++++----------------
 2 files changed, 49 insertions(+), 18 deletions(-)

diff --git a/doc/filters.texi b/doc/filters.texi
index 8ddbac4..f8279bd 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -3936,6 +3936,20 @@ the @var{movie} filter.
 You can chain together more overlays but you should test the
 efficiency of such approach.
 
+ at subsection Commands
+
+This filter supports the following command:
+ at table @option
+ at item x
+Set the @option{x} option expression.
+
+ at item y
+Set the @option{y} option expression.
+
+ at item enable
+Set the @option{enable} option expression.
+ at end table
+
 @subsection Examples
 
 @itemize
diff --git a/libavfilter/vf_overlay.c b/libavfilter/vf_overlay.c
index c9dedb5..b2d68ba 100644
--- a/libavfilter/vf_overlay.c
+++ b/libavfilter/vf_overlay.c
@@ -168,6 +168,36 @@ static av_cold void uninit(AVFilterContext *ctx)
     ff_bufqueue_discard_all(&over->queue_over);
 }
 
+static int configure_expr(AVExpr **pexpr, const char *expr, void *log_ctx)
+{
+    int ret;
+
+    if (*pexpr)
+        av_expr_free(*pexpr);
+    *pexpr = NULL;
+    ret = av_expr_parse(pexpr, expr, var_names,
+                        NULL, NULL, NULL, NULL, 0, log_ctx);
+    if (ret < 0)
+        av_log(NULL, AV_LOG_ERROR,
+               "Error when evaluating the expression '%s'\n", expr);
+    return ret;
+}
+
+static int process_command(AVFilterContext *ctx, const char *cmd, const char *args,
+                           char *res, int res_len, int flags)
+{
+    OverlayContext *over = ctx->priv;
+
+    if      (!strcmp(cmd, "x"))
+        return configure_expr(&over->x_pexpr, args, ctx);
+    else if (!strcmp(cmd, "y"))
+        return configure_expr(&over->y_pexpr, args, ctx);
+    else if (!strcmp(cmd, "enable"))
+        return configure_expr(&over->enable_pexpr, args, ctx);
+    else
+        return AVERROR(ENOSYS);
+}
+
 static int query_formats(AVFilterContext *ctx)
 {
     OverlayContext *over = ctx->priv;
@@ -250,7 +280,6 @@ static int config_input_overlay(AVFilterLink *inlink)
 {
     AVFilterContext *ctx  = inlink->dst;
     OverlayContext  *over = inlink->dst->priv;
-    char *expr;
     int ret;
     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
 
@@ -270,18 +299,10 @@ static int config_input_overlay(AVFilterLink *inlink)
     over->var_values[VAR_T]     = NAN;
     over->var_values[VAR_POS]   = NAN;
 
-    expr = over->x_expr;
-    if ((ret = av_expr_parse(&over->x_pexpr, expr, var_names,
-                             NULL, NULL, NULL, NULL, 0, ctx)) < 0)
-        goto fail;
-    expr = over->y_expr;
-    if ((ret = av_expr_parse(&over->y_pexpr, expr, var_names,
-                             NULL, NULL, NULL, NULL, 0, ctx)) < 0)
-        goto fail;
-    expr = over->enable_expr;
-    if ((ret = av_expr_parse(&over->enable_pexpr, expr, var_names,
-                             NULL, NULL, NULL, NULL, 0, ctx)) < 0)
-        goto fail;
+    if ((ret = configure_expr(&over->x_pexpr, over->x_expr, ctx) < 0) ||
+        (ret = configure_expr(&over->y_pexpr, over->y_expr, ctx) < 0) ||
+        (ret = configure_expr(&over->enable_pexpr, over->enable_expr, ctx) < 0))
+        return ret;
 
     over->overlay_is_packed_rgb =
         ff_fill_rgba_map(over->overlay_rgba_map, inlink->format) >= 0;
@@ -294,11 +315,6 @@ static int config_input_overlay(AVFilterLink *inlink)
            ctx->inputs[OVERLAY]->w, ctx->inputs[OVERLAY]->h,
            av_get_pix_fmt_name(ctx->inputs[OVERLAY]->format));
     return 0;
-
-fail:
-    av_log(NULL, AV_LOG_ERROR,
-           "Error when evaluating the expression '%s'\n", expr);
-    return ret;
 }
 
 static int config_output(AVFilterLink *outlink)
@@ -695,6 +711,7 @@ AVFilter avfilter_vf_overlay = {
     .priv_size = sizeof(OverlayContext),
 
     .query_formats = query_formats,
+    .process_command = process_command,
 
     .inputs    = avfilter_vf_overlay_inputs,
     .outputs   = avfilter_vf_overlay_outputs,
-- 
1.7.9.5