[FFmpeg-devel] [PATCH] vf_tinterlace: add vertical low-pass-filter option to mode 4 and 5
Mark Himsley
mark at mdsh.com
Fri Dec 21 13:58:07 CET 2012
On 19/12/2012 17:17, Mark Himsley wrote:
> Low-pass filtering is required when creating an interlaced destination
> from a progressive source which contains high-frequency vertical detail.
> Filtering will reduce interlace 'twitter' and Moire patterning.
minor update to correct the consts.
--
Mark
-------------- next part --------------
diff --git a/doc/filters.texi b/doc/filters.texi
index a2b4fbe..0198f9a 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -3900,9 +3900,28 @@ Perform various types of temporal field interlacing.
Frames are counted starting from 1, so the first input frame is
considered odd.
-This filter accepts a single option @option{mode} specifying the mode,
-which can be specified either by specyfing @code{mode=VALUE} either
-specifying the value alone. Available values are:
+This filter accepts upto two options in the form of @var{key}=@var{value}
+pairs separated by ":".
+Alternatively, the @var{mode} option can be specified as a value alone,
+optionally followed by a ":" and a @var{key}=@var{value} option.
+
+A description of the accepted options follows.
+
+ at table @option
+
+ at item mode
+Specifies the mode of the interlacing. This option can also be
+specified as a value alone. See below for a list of values for this option.
+
+ at item filter
+Specifies whether a vertical low-pass filtering will be applied.
+The default value is @code{0}, meaning no filtering will be applied.
+The value of @code{1} will enable vertical low-pass filtering for
+ at var{mode} @code{4} and @code{5}.
+
+ at end table
+
+Available values for @var{mode} are:
@table @samp
@item merge, 0
diff --git a/libavfilter/vf_tinterlace.c b/libavfilter/vf_tinterlace.c
index 843a66c..df88674 100644
--- a/libavfilter/vf_tinterlace.c
+++ b/libavfilter/vf_tinterlace.c
@@ -45,6 +45,7 @@ enum TInterlaceMode {
typedef struct {
const AVClass *class;
enum TInterlaceMode mode; ///< interlace mode selected
+ int filter; ///< interlace filtering enabled
int frame; ///< number of the output frame
int vsub; ///< chroma vertical subsampling
AVFilterBufferRef *cur;
@@ -65,6 +66,7 @@ static const AVOption tinterlace_options[] = {
{"interleave_top", "interleave top and bottom fields", 0, AV_OPT_TYPE_CONST, {.i64=MODE_INTERLEAVE_TOP}, INT_MIN, INT_MAX, FLAGS, "mode"},
{"interleave_bottom", "interleave bottom and top fields", 0, AV_OPT_TYPE_CONST, {.i64=MODE_INTERLEAVE_BOTTOM}, INT_MIN, INT_MAX, FLAGS, "mode"},
{"interlacex2", "interlace fields from two consecutive frames", 0, AV_OPT_TYPE_CONST, {.i64=MODE_INTERLACEX2}, INT_MIN, INT_MAX, FLAGS, "mode"},
+ {"filter", "enable interlace filtering", OFFSET(filter), AV_OPT_TYPE_INT, {.i64=0}, 0, 1, FLAGS, "filter"},
{NULL}
};
@@ -142,8 +144,13 @@ static int config_out_props(AVFilterLink *outlink)
tinterlace->black_linesize[i] * h);
}
}
- av_log(ctx, AV_LOG_VERBOSE, "mode:%d h:%d -> h:%d\n",
- tinterlace->mode, inlink->h, outlink->h);
+ if (tinterlace->filter && !(tinterlace->mode == MODE_INTERLEAVE_TOP
+ || tinterlace->mode == MODE_INTERLEAVE_BOTTOM)) {
+ av_log(ctx, AV_LOG_WARNING, "filter not required for mode:%d\n", tinterlace->mode);
+ tinterlace->filter = 0;
+ }
+ av_log(ctx, AV_LOG_VERBOSE, "mode:%d filter:%s h:%d -> h:%d\n",
+ tinterlace->mode, tinterlace->filter ? "on" : "off", inlink->h, outlink->h);
return 0;
}
@@ -189,6 +196,66 @@ void copy_picture_field(uint8_t *dst[4], int dst_linesize[4],
}
}
+/**
+ * Copy with low-pass filter picture field from src to dst.
+ * Low-pass filtering is required when creating an interlaced destination from
+ * a progressive source which contains high-frequency vertical detail.
+ * Filtering will reduce interlace 'twitter' and Moiré patterning.
+ * Other than low-pass filtering, this functions identicaly to
+ * copy_picture_field() above.
+ *
+ * @param src_field copy from upper, lower field or both
+ * @param interleave leave a padding line between each copied line
+ * @param dst_field copy to upper or lower field,
+ * only meaningful when interleave is selected
+ */
+static inline
+void filter_copy_picture_field(uint8_t *dst[4], int dst_linesize[4],
+ const uint8_t *src[4], int src_linesize[4],
+ enum AVPixelFormat format, int w, int src_h,
+ int src_field, int interleave, int dst_field)
+{
+ const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
+ int plane, vsub = desc->log2_chroma_h;
+ int k = src_field == FIELD_UPPER_AND_LOWER ? 1 : 2;
+
+ for (plane = 0; plane < desc->nb_components; plane++) {
+ int lines = plane == 1 || plane == 2 ? src_h >> vsub : src_h;
+ int linesize = av_image_get_linesize(format, w, plane);
+ uint8_t *dstp = dst[plane];
+ const uint8_t *srcp = src[plane];
+ int srcp_linesize;
+ int dstp_linesize;
+
+ if (linesize < 0)
+ return;
+
+ lines /= k;
+ if (src_field == FIELD_LOWER)
+ srcp += src_linesize[plane];
+ if (interleave && dst_field == FIELD_LOWER)
+ dstp += dst_linesize[plane];
+
+ srcp_linesize = src_linesize[plane] * k;
+ dstp_linesize = dst_linesize[plane] * (interleave ? 2 : 1);
+
+ for (int h = lines; h > 0; h--) {
+ const uint8_t *srcp_above = srcp - src_linesize[plane];
+ const uint8_t *srcp_below = srcp + src_linesize[plane];
+ if (h == lines) srcp_above = srcp; // there is no line above
+ if (h == 1) srcp_below = srcp; // there is no line below
+ for (int i = 0; i < linesize; i++) {
+ // this calculation is an integer representation of
+ // '0.5 * current + 0.25 * above + 0.25 + below'
+ // '1 +' is for rounding
+ dstp[i] = (1 + srcp[i] + srcp[i] + srcp_above[i] + srcp_below[i]) >> 2;
+ }
+ dstp += dstp_linesize;
+ srcp += srcp_linesize;
+ }
+ }
+}
+
static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *picref)
{
AVFilterContext *ctx = inlink->dst;
@@ -267,17 +334,29 @@ static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *picref)
avfilter_copy_buffer_ref_props(out, cur);
out->video->interlaced = 1;
out->video->top_field_first = tff;
-
- /* copy upper/lower field from cur */
- copy_picture_field(out->data, out->linesize,
- (const uint8_t **)cur->data, cur->linesize,
- inlink->format, inlink->w, inlink->h,
- tff ? FIELD_UPPER : FIELD_LOWER, 1, tff ? FIELD_UPPER : FIELD_LOWER);
- /* copy lower/upper field from next */
- copy_picture_field(out->data, out->linesize,
- (const uint8_t **)next->data, next->linesize,
- inlink->format, inlink->w, inlink->h,
- tff ? FIELD_LOWER : FIELD_UPPER, 1, tff ? FIELD_LOWER : FIELD_UPPER);
+ if (tinterlace->filter) {
+ /* copy upper/lower field from cur */
+ filter_copy_picture_field(out->data, out->linesize,
+ (const uint8_t **)cur->data, cur->linesize,
+ inlink->format, inlink->w, inlink->h,
+ tff ? FIELD_UPPER : FIELD_LOWER, 1, tff ? FIELD_UPPER : FIELD_LOWER);
+ /* copy lower/upper field from next */
+ filter_copy_picture_field(out->data, out->linesize,
+ (const uint8_t **)next->data, next->linesize,
+ inlink->format, inlink->w, inlink->h,
+ tff ? FIELD_LOWER : FIELD_UPPER, 1, tff ? FIELD_LOWER : FIELD_UPPER);
+ } else {
+ /* copy upper/lower field from cur */
+ copy_picture_field(out->data, out->linesize,
+ (const uint8_t **)cur->data, cur->linesize,
+ inlink->format, inlink->w, inlink->h,
+ tff ? FIELD_UPPER : FIELD_LOWER, 1, tff ? FIELD_UPPER : FIELD_LOWER);
+ /* copy lower/upper field from next */
+ copy_picture_field(out->data, out->linesize,
+ (const uint8_t **)next->data, next->linesize,
+ inlink->format, inlink->w, inlink->h,
+ tff ? FIELD_LOWER : FIELD_UPPER, 1, tff ? FIELD_LOWER : FIELD_UPPER);
+ }
avfilter_unref_bufferp(&tinterlace->next);
break;
case MODE_INTERLACEX2: /* re-interlace preserving image height, double frame rate */
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