[FFmpeg-devel] [PATCH] lavfi/decimate: use named options

[Stefano Sabatini]

TODO: bump micro
---
 doc/filters.texi          |   23 +++++++++++++---------
 libavfilter/vf_decimate.c |   48 ++++++++++++++++++++++++---------------------
 2 files changed, 40 insertions(+), 31 deletions(-)

diff --git a/doc/filters.texi b/doc/filters.texi
index 43bfd9c..3be8363 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -2069,11 +2069,14 @@ for very-low-bitrate encoding (e.g. streaming over dialup modem), but
 it could in theory be used for fixing movies that were
 inverse-telecined incorrectly.
 
-It accepts the following parameters:
- at var{max}:@var{hi}:@var{lo}:@var{frac}.
+The filter accepts parameters as a list of @var{key}=@var{value}
+pairs, separated by ":".  If the key of the first options is omitted,
+the arguments are interpreted according to the syntax:
+ at option{max}:@option{hi}:@option{lo}:@option{frac}.
 
- at table @option
+A description of the accepted options follows.
 
+ at table @option
 @item max
 Set the maximum number of consecutive frames which can be dropped (if
 positive), or the minimum interval between dropped frames (if
@@ -2082,20 +2085,22 @@ number of previous sequentially dropped frames.
 
 Default value is 0.
 
- at item hi, lo, frac
+ at item hi
+ at item lo
+ at item frac
 Set the dropping threshold values.
 
-Values for @var{hi} and @var{lo} are for 8x8 pixel blocks and
+Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
 represent actual pixel value differences, so a threshold of 64
 corresponds to 1 unit of difference for each pixel, or the same spread
 out differently over the block.
 
 A frame is a candidate for dropping if no 8x8 blocks differ by more
-than a threshold of @var{hi}, and if no more than @var{frac} blocks (1
-meaning the whole image) differ by more than a threshold of @var{lo}.
+than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
+meaning the whole image) differ by more than a threshold of @option{lo}.
 
-Default value for @var{hi} is 64*12, default value for @var{lo} is
-64*5, and default value for @var{frac} is 0.33.
+Default value for @option{hi} is 64*12, default value for @option{lo} is
+64*5, and default value for @option{frac} is 0.33.
 @end table
 
 @section delogo
diff --git a/libavfilter/vf_decimate.c b/libavfilter/vf_decimate.c
index 0d89b81..4982f79 100644
--- a/libavfilter/vf_decimate.c
+++ b/libavfilter/vf_decimate.c
@@ -24,6 +24,7 @@
  * Rich Felker.
  */
 
+#include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
 #include "libavutil/timestamp.h"
 #include "libavcodec/dsputil.h"
@@ -33,6 +34,7 @@
 #include "video.h"
 
 typedef struct {
+    const AVClass *class;
     int lo, hi;                    ///< lower and higher threshold number of differences
                                    ///< values for 8x8 blocks
 
@@ -50,6 +52,20 @@ typedef struct {
     AVCodecContext *avctx;         ///< codec context required for the DSPContext
 } DecimateContext;
 
+#define OFFSET(x) offsetof(DecimateContext, x)
+#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
+
+static const AVOption decimate_options[] = {
+    { "max",  "set the maximum number of consecutive dropped frames (positive), or minimum interval between dropped frames (minimum)",
+      OFFSET(max_drop_count), AV_OPT_TYPE_INT, {.i64=0}, INT_MIN, INT_MAX, FLAGS },
+    { "hi",   "set high dropping threshold", OFFSET(hi), AV_OPT_TYPE_INT, {.i64=64*12}, INT_MIN, INT_MAX, FLAGS },
+    { "lo",   "set low dropping threshold", OFFSET(lo), AV_OPT_TYPE_INT, {.i64=64*5}, INT_MIN, INT_MAX, FLAGS },
+    { "frac", "set fraction dropping threshold",  OFFSET(frac), AV_OPT_TYPE_FLOAT, {.dbl=0.33}, 0, 1, FLAGS },
+    { NULL },
+};
+
+AVFILTER_DEFINE_CLASS(decimate);
+
 /**
  * Return 1 if the two planes are different, 0 otherwise.
  */
@@ -116,29 +132,14 @@ static int decimate_frame(AVFilterContext *ctx,
 static av_cold int init(AVFilterContext *ctx, const char *args)
 {
     DecimateContext *decimate = ctx->priv;
+    static const char *shorthand[] = { "max", "hi", "lo", "frac", NULL };
+    int ret;
 
-    /* set default values */
-    decimate->drop_count = decimate->max_drop_count = 0;
-    decimate->lo = 64*5;
-    decimate->hi = 64*12;
-    decimate->frac = 0.33;
-
-    if (args) {
-        char c1, c2, c3, c4;
-        int n = sscanf(args, "%d%c%d%c%d%c%f%c",
-                       &decimate->max_drop_count, &c1,
-                       &decimate->hi, &c2, &decimate->lo, &c3,
-                       &decimate->frac, &c4);
-        if (n != 1 &&
-            (n != 3 || c1 != ':') &&
-            (n != 5 || c1 != ':' || c2 != ':') &&
-            (n != 7 || c1 != ':' || c2 != ':' || c3 != ':')) {
-            av_log(ctx, AV_LOG_ERROR,
-                   "Invalid syntax for argument '%s': "
-                   "must be in the form 'max:hi:lo:frac'\n", args);
-            return AVERROR(EINVAL);
-        }
-    }
+    decimate->class = &decimate_class;
+    av_opt_set_defaults(decimate);
+
+    if ((ret = av_opt_set_from_string(decimate, args, shorthand, "=", ":")) < 0)
+        return ret;
 
     av_log(ctx, AV_LOG_VERBOSE, "max_drop_count:%d hi:%d lo:%d frac:%f\n",
            decimate->max_drop_count, decimate->hi, decimate->lo, decimate->frac);
@@ -156,6 +157,7 @@ static av_cold void uninit(AVFilterContext *ctx)
     DecimateContext *decimate = ctx->priv;
     avfilter_unref_bufferp(&decimate->ref);
     avcodec_close(decimate->avctx);
+    av_opt_free(decimate);
     av_freep(&decimate->avctx);
 }
 
@@ -260,4 +262,6 @@ AVFilter avfilter_vf_decimate = {
     .query_formats = query_formats,
     .inputs        = decimate_inputs,
     .outputs       = decimate_outputs,
+
+    .priv_class    = &decimate_class,
 };
-- 
1.7.9.5