[FFmpeg-devel] [PATCH] vf_tinterlace: add vertical low-pass-filter option to mode 4 and 5
Mark Himsley
mark at mdsh.com
Fri Dec 28 01:11:52 CET 2012
On 25/12/2012 10:52, Stefano Sabatini wrote:
> On date Saturday 2012-12-22 23:25:19 +0000, Mark Himsley encoded:
>> On 22/12/2012 12:10, Stefano Sabatini wrote:
>>> On date Friday 2012-12-21 12:58:07 +0000, Mark Himsley encoded:
>>>> 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.
>>>
>>> Sorry for the slow reply.
>>
>> I'm grateful for the review.
>>
>>>> + * Other than low-pass filtering, this functions identicaly to
>>>> + * copy_picture_field() above.
>>>
>>> Note: would it make sense to move this to a separate filter?
>>
>> I don't think so. I can't currently think of a use-case.
>> Were this filter to be separate from tinterlace, to insert just before
>> the tinterlace filter, then it would have to do twice as many
>> calculations - it would calculate all the lines that were about to be
>> dropped in the interleave interlace. I do not think that is a good idea.
>>
>> Updated patch attached.
>>
>
> Wrong patch?
>
True. This is what I should have sent.
--
Mark
-------------- next part --------------
diff --git a/doc/filters.texi b/doc/filters.texi
index 17e2af7..c2ead91 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -3923,9 +3923,25 @@ 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 up to 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} pair.
+
+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 flags
+Specifies flags influencing the filter process.
+
+ at end table
+
+Available values for @var{mode} are:
@table @samp
@item merge, 0
@@ -3965,6 +3981,21 @@ compatibility reasons.
Default mode is @code{merge}.
+Available value for @var{flags} is:
+
+ at table @samp
+ at item low_pass_filter
+Enable vertical low-pass filtering in the filter.
+Vertical 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 Moir@'e
+patterning.
+
+Vertical low-pass filtering can only be enabled for @var{mode}
+ at code{interleave_top} and @code{interleave_bottom}.
+
+ at end table
+
@section transpose
Transpose rows with columns in the input video and optionally flip it.
diff --git a/libavfilter/vf_tinterlace.c b/libavfilter/vf_tinterlace.c
index 843a66c..8926f77 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 flags; ///< flags for the tinterlace filter
int frame; ///< number of the output frame
int vsub; ///< chroma vertical subsampling
AVFilterBufferRef *cur;
@@ -55,6 +56,7 @@ typedef struct {
#define OFFSET(x) offsetof(TInterlaceContext, x)
#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
+#define TINTERLACE_FLAG_VLPF 01
static const AVOption tinterlace_options[] = {
{"mode", "select interlace mode", OFFSET(mode), AV_OPT_TYPE_INT, {.i64=MODE_MERGE}, 0, MODE_NB-1, FLAGS, "mode"},
@@ -65,6 +67,8 @@ 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"},
+ {"flags", "set flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = 0}, 0, INT_MAX, 0, "flags" },
+ {"low_pass_filter", "enable vertical low-pass filter", 0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_VLPF}, INT_MIN, INT_MAX, FLAGS, "flags" },
{NULL}
};
@@ -142,8 +146,15 @@ 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->flags & TINTERLACE_FLAG_VLPF)
+ && !(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->flags &= !TINTERLACE_FLAG_VLPF;
+ }
+ av_log(ctx, AV_LOG_VERBOSE, "mode:%d filter:%s h:%d -> h:%d\n",
+ tinterlace->mode, (tinterlace->flags & TINTERLACE_FLAG_VLPF) ? "on" : "off",
+ inlink->h, outlink->h);
return 0;
}
@@ -159,12 +170,14 @@ static int config_out_props(AVFilterLink *outlink)
* @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
+ * @param flags context flags
*/
static inline
void 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)
+ int src_field, int interleave, int dst_field,
+ int flags)
{
const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
int plane, vsub = desc->log2_chroma_h;
@@ -184,8 +197,30 @@ void copy_picture_field(uint8_t *dst[4], int dst_linesize[4],
srcp += src_linesize[plane];
if (interleave && dst_field == FIELD_LOWER)
dstp += dst_linesize[plane];
- av_image_copy_plane(dstp, dst_linesize[plane] * (interleave ? 2 : 1),
+ if (flags & TINTERLACE_FLAG_VLPF) {
+ // 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.
+ int srcp_linesize = src_linesize[plane] * k;
+ int 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;
+ }
+ } else {
+ av_image_copy_plane(dstp, dst_linesize[plane] * (interleave ? 2 : 1),
srcp, src_linesize[plane]*k, linesize, lines);
+ }
}
}
@@ -222,12 +257,12 @@ static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *picref)
copy_picture_field(out->data, out->linesize,
(const uint8_t **)cur->data, cur->linesize,
inlink->format, inlink->w, inlink->h,
- FIELD_UPPER_AND_LOWER, 1, FIELD_UPPER);
+ FIELD_UPPER_AND_LOWER, 1, FIELD_UPPER, tinterlace->flags);
/* write even frame lines into the lower field of the new frame */
copy_picture_field(out->data, out->linesize,
(const uint8_t **)next->data, next->linesize,
inlink->format, inlink->w, inlink->h,
- FIELD_UPPER_AND_LOWER, 1, FIELD_LOWER);
+ FIELD_UPPER_AND_LOWER, 1, FIELD_LOWER, tinterlace->flags);
avfilter_unref_bufferp(&tinterlace->next);
break;
@@ -248,12 +283,12 @@ static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *picref)
copy_picture_field(out->data, out->linesize,
(const uint8_t **)cur->data, cur->linesize,
inlink->format, inlink->w, inlink->h,
- FIELD_UPPER_AND_LOWER, 1, field);
+ FIELD_UPPER_AND_LOWER, 1, field, tinterlace->flags);
/* pad with black the other field */
copy_picture_field(out->data, out->linesize,
(const uint8_t **)tinterlace->black_data, tinterlace->black_linesize,
inlink->format, inlink->w, inlink->h,
- FIELD_UPPER_AND_LOWER, 1, !field);
+ FIELD_UPPER_AND_LOWER, 1, !field, tinterlace->flags);
break;
/* interleave upper/lower lines from odd frames with lower/upper lines from even frames,
@@ -272,12 +307,14 @@ static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *picref)
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);
+ tff ? FIELD_UPPER : FIELD_LOWER, 1, tff ? FIELD_UPPER : FIELD_LOWER,
+ tinterlace->flags);
/* 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);
+ tff ? FIELD_LOWER : FIELD_UPPER, 1, tff ? FIELD_LOWER : FIELD_UPPER,
+ tinterlace->flags);
avfilter_unref_bufferp(&tinterlace->next);
break;
case MODE_INTERLACEX2: /* re-interlace preserving image height, double frame rate */
@@ -302,12 +339,14 @@ static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *picref)
copy_picture_field(out->data, out->linesize,
(const uint8_t **)cur->data, cur->linesize,
inlink->format, inlink->w, inlink->h,
- tff ? FIELD_LOWER : FIELD_UPPER, 1, tff ? FIELD_LOWER : FIELD_UPPER);
+ tff ? FIELD_LOWER : FIELD_UPPER, 1, tff ? FIELD_LOWER : FIELD_UPPER,
+ tinterlace->flags);
/* write next frame first field lines into the first field of the new frame */
copy_picture_field(out->data, out->linesize,
(const uint8_t **)next->data, next->linesize,
inlink->format, inlink->w, inlink->h,
- tff ? FIELD_UPPER : FIELD_LOWER, 1, tff ? FIELD_UPPER : FIELD_LOWER);
+ tff ? FIELD_UPPER : FIELD_LOWER, 1, tff ? FIELD_UPPER : FIELD_LOWER,
+ tinterlace->flags);
break;
default:
av_assert0(0);
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