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a7f6bfdc18
ffmpeg/libavfilter/vf_tinterlace.c
Thomas Mundt a7f6bfdc18 avfilter/interlace: prevent over-sharpening with the complex low-pass filter 
The complex vertical low-pass filter slightly over-sharpens the picture. This becomes visible when several transcodings are cascaded and the error potentises, e.g. some generations of HD->SD SD->HD.
To prevent this behaviour the destination pixel must not exceed the source pixel when the average of the pixels above and below is less than the source pixel. And the other way around.

Tested and approved in a visual transcoding cascade test by video professionals.
SSIM/PSNR test with the first generation of an HD->SD file as a reference against the 6th generation(3 x SD->HD HD->SD):
Results without the patch:
SSIM Y:0.956508 (13.615881) U:0.991601 (20.757750) V:0.993004 (21.551382) All:0.974405 (15.918463)
PSNR y:31.838009 u:48.424280 v:48.962711 average:34.759466 min:31.699297 max:40.857847
Results with the patch:
SSIM Y:0.970051 (15.236232) U:0.991883 (20.905857) V:0.993174 (21.658049) All:0.981290 (17.279202)
PSNR y:34.412108 u:48.504454 v:48.969496 average:37.264644 min:34.310637 max:42.373392

Signed-off-by: Thomas Mundt <tmundt75@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
2017-09-15 22:40:21 +02:00

477 lines
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/*
* Copyright (c) 2017 Thomas Mundt <tmundt75@gmail.com>
* Copyright (c) 2011 Stefano Sabatini
* Copyright (c) 2010 Baptiste Coudurier
* Copyright (c) 2003 Michael Zucchi <notzed@ximian.com>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with FFmpeg if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/**
* @file
* temporal field interlace filter, ported from MPlayer/libmpcodecs
*/
#include "libavutil/opt.h"
#include "libavutil/imgutils.h"
#include "libavutil/avassert.h"
#include "avfilter.h"
#include "internal.h"
#include "tinterlace.h"
#define OFFSET(x) offsetof(TInterlaceContext, x)
#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
static const AVOption tinterlace_options[] = {
{"mode", "select interlace mode", OFFSET(mode), AV_OPT_TYPE_INT, {.i64=MODE_MERGE}, 0, MODE_NB-1, FLAGS, "mode"},
{"merge", "merge fields", 0, AV_OPT_TYPE_CONST, {.i64=MODE_MERGE}, INT_MIN, INT_MAX, FLAGS, "mode"},
{"drop_even", "drop even fields", 0, AV_OPT_TYPE_CONST, {.i64=MODE_DROP_EVEN}, INT_MIN, INT_MAX, FLAGS, "mode"},
{"drop_odd", "drop odd fields", 0, AV_OPT_TYPE_CONST, {.i64=MODE_DROP_ODD}, INT_MIN, INT_MAX, FLAGS, "mode"},
{"pad", "pad alternate lines with black", 0, AV_OPT_TYPE_CONST, {.i64=MODE_PAD}, INT_MIN, INT_MAX, FLAGS, "mode"},
{"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"},
{"mergex2", "merge fields keeping same frame rate", 0, AV_OPT_TYPE_CONST, {.i64=MODE_MERGEX2}, 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" },
{"vlpf", "enable vertical low-pass filter", 0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_VLPF}, INT_MIN, INT_MAX, FLAGS, "flags" },
{"complex_filter", "enable complex vertical low-pass filter", 0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_CVLPF},INT_MIN, INT_MAX, FLAGS, "flags" },
{"cvlpf", "enable complex vertical low-pass filter", 0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_CVLPF},INT_MIN, INT_MAX, FLAGS, "flags" },
{"exact_tb", "force a timebase which can represent timestamps exactly", 0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_EXACT_TB}, INT_MIN, INT_MAX, FLAGS, "flags" },
{NULL}
};
AVFILTER_DEFINE_CLASS(tinterlace);
#define FULL_SCALE_YUVJ_FORMATS \
AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P, AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P
static const enum AVPixelFormat full_scale_yuvj_pix_fmts[] = {
FULL_SCALE_YUVJ_FORMATS, AV_PIX_FMT_NONE
};
static const AVRational standard_tbs[] = {
{1, 25},
{1, 30},
{1001, 30000},
};
static int query_formats(AVFilterContext *ctx)
{
static const enum AVPixelFormat pix_fmts[] = {
AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV411P,
AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV422P,
AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV444P,
AV_PIX_FMT_YUVA420P, AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUVA444P,
AV_PIX_FMT_GRAY8, FULL_SCALE_YUVJ_FORMATS,
AV_PIX_FMT_NONE
};
AVFilterFormats *fmts_list = ff_make_format_list(pix_fmts);
if (!fmts_list)
return AVERROR(ENOMEM);
return ff_set_common_formats(ctx, fmts_list);
}
static void lowpass_line_c(uint8_t *dstp, ptrdiff_t width, const uint8_t *srcp,
ptrdiff_t mref, ptrdiff_t pref)
{
const uint8_t *srcp_above = srcp + mref;
const uint8_t *srcp_below = srcp + pref;
int i;
for (i = 0; i < width; 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;
}
}
static void lowpass_line_complex_c(uint8_t *dstp, ptrdiff_t width, const uint8_t *srcp,
ptrdiff_t mref, ptrdiff_t pref)
{
const uint8_t *srcp_above = srcp + mref;
const uint8_t *srcp_below = srcp + pref;
const uint8_t *srcp_above2 = srcp + mref * 2;
const uint8_t *srcp_below2 = srcp + pref * 2;
int i, srcp_x, srcp_ab;
for (i = 0; i < width; i++) {
// this calculation is an integer representation of
// '0.75 * current + 0.25 * above + 0.25 * below - 0.125 * above2 - 0.125 * below2'
// '4 +' is for rounding.
srcp_x = srcp[i] << 1;
srcp_ab = srcp_above[i] + srcp_below[i];
dstp[i] = av_clip_uint8((4 + ((srcp[i] + srcp_x + srcp_ab) << 1)
- srcp_above2[i] - srcp_below2[i]) >> 3);
// Prevent over-sharpening:
// dst must not exceed src when the average of above and below
// is less than src. And the other way around.
if (srcp_ab > srcp_x) {
if (dstp[i] < srcp[i])
dstp[i] = srcp[i];
} else if (dstp[i] > srcp[i])
dstp[i] = srcp[i];
}
}
static av_cold void uninit(AVFilterContext *ctx)
{
TInterlaceContext *tinterlace = ctx->priv;
av_frame_free(&tinterlace->cur );
av_frame_free(&tinterlace->next);
av_freep(&tinterlace->black_data[0]);
}
static int config_out_props(AVFilterLink *outlink)
{
AVFilterContext *ctx = outlink->src;
AVFilterLink *inlink = outlink->src->inputs[0];
const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(outlink->format);
TInterlaceContext *tinterlace = ctx->priv;
int i;
tinterlace->vsub = desc->log2_chroma_h;
outlink->w = inlink->w;
outlink->h = tinterlace->mode == MODE_MERGE || tinterlace->mode == MODE_PAD || tinterlace->mode == MODE_MERGEX2?
inlink->h*2 : inlink->h;
if (tinterlace->mode == MODE_MERGE || tinterlace->mode == MODE_PAD || tinterlace->mode == MODE_MERGEX2)
outlink->sample_aspect_ratio = av_mul_q(inlink->sample_aspect_ratio,
av_make_q(2, 1));
if (tinterlace->mode == MODE_PAD) {
uint8_t black[4] = { 16, 128, 128, 16 };
int i, ret;
if (ff_fmt_is_in(outlink->format, full_scale_yuvj_pix_fmts))
black[0] = black[3] = 0;
ret = av_image_alloc(tinterlace->black_data, tinterlace->black_linesize,
outlink->w, outlink->h, outlink->format, 16);
if (ret < 0)
return ret;
/* fill black picture with black */
for (i = 0; i < 4 && tinterlace->black_data[i]; i++) {
int h = i == 1 || i == 2 ? AV_CEIL_RSHIFT(outlink->h, desc->log2_chroma_h) : outlink->h;
memset(tinterlace->black_data[i], black[i],
tinterlace->black_linesize[i] * h);
}
}
if ((tinterlace->flags & TINTERLACE_FLAG_VLPF
|| tinterlace->flags & TINTERLACE_FLAG_CVLPF)
&& !(tinterlace->mode == MODE_INTERLEAVE_TOP
|| tinterlace->mode == MODE_INTERLEAVE_BOTTOM)) {
av_log(ctx, AV_LOG_WARNING, "low_pass_filter flags ignored with mode %d\n",
tinterlace->mode);
tinterlace->flags &= ~TINTERLACE_FLAG_VLPF;
tinterlace->flags &= ~TINTERLACE_FLAG_CVLPF;
}
tinterlace->preout_time_base = inlink->time_base;
if (tinterlace->mode == MODE_INTERLACEX2) {
tinterlace->preout_time_base.den *= 2;
outlink->frame_rate = av_mul_q(inlink->frame_rate, (AVRational){2,1});
outlink->time_base = av_mul_q(inlink->time_base , (AVRational){1,2});
} else if (tinterlace->mode == MODE_MERGEX2) {
outlink->frame_rate = inlink->frame_rate;
outlink->time_base = inlink->time_base;
} else if (tinterlace->mode != MODE_PAD) {
outlink->frame_rate = av_mul_q(inlink->frame_rate, (AVRational){1,2});
outlink->time_base = av_mul_q(inlink->time_base , (AVRational){2,1});
}
for (i = 0; i<FF_ARRAY_ELEMS(standard_tbs); i++){
if (!av_cmp_q(standard_tbs[i], outlink->time_base))
break;
}
if (i == FF_ARRAY_ELEMS(standard_tbs) ||
(tinterlace->flags & TINTERLACE_FLAG_EXACT_TB))
outlink->time_base = tinterlace->preout_time_base;
if (tinterlace->flags & TINTERLACE_FLAG_CVLPF) {
tinterlace->lowpass_line = lowpass_line_complex_c;
if (ARCH_X86)
ff_tinterlace_init_x86(tinterlace);
} else if (tinterlace->flags & TINTERLACE_FLAG_VLPF) {
tinterlace->lowpass_line = lowpass_line_c;
if (ARCH_X86)
ff_tinterlace_init_x86(tinterlace);
}
av_log(ctx, AV_LOG_VERBOSE, "mode:%d filter:%s h:%d -> h:%d\n", tinterlace->mode,
(tinterlace->flags & TINTERLACE_FLAG_CVLPF) ? "complex" :
(tinterlace->flags & TINTERLACE_FLAG_VLPF) ? "linear" : "off",
inlink->h, outlink->h);
return 0;
}
#define FIELD_UPPER 0
#define FIELD_LOWER 1
#define FIELD_UPPER_AND_LOWER 2
/**
* Copy picture field from src to dst.
*
* @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
* @param flags context flags
*/
static inline
void copy_picture_field(TInterlaceContext *tinterlace,
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 flags)
{
const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
int hsub = desc->log2_chroma_w;
int plane, vsub = desc->log2_chroma_h;
int k = src_field == FIELD_UPPER_AND_LOWER ? 1 : 2;
int h;
for (plane = 0; plane < desc->nb_components; plane++) {
int lines = plane == 1 || plane == 2 ? AV_CEIL_RSHIFT(src_h, vsub) : src_h;
int cols = plane == 1 || plane == 2 ? AV_CEIL_RSHIFT( w, hsub) : w;
uint8_t *dstp = dst[plane];
const uint8_t *srcp = src[plane];
lines = (lines + (src_field == FIELD_UPPER)) / k;
if (src_field == FIELD_LOWER)
srcp += src_linesize[plane];
if (interleave && dst_field == FIELD_LOWER)
dstp += dst_linesize[plane];
// 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.
if (flags & TINTERLACE_FLAG_CVLPF) {
int srcp_linesize = src_linesize[plane] * k;
int dstp_linesize = dst_linesize[plane] * (interleave ? 2 : 1);
for (h = lines; h > 0; h--) {
ptrdiff_t pref = src_linesize[plane];
ptrdiff_t mref = -pref;
if (h >= (lines - 1)) mref = 0;
else if (h <= 2) pref = 0;
tinterlace->lowpass_line(dstp, cols, srcp, mref, pref);
dstp += dstp_linesize;
srcp += srcp_linesize;
}
} else if (flags & TINTERLACE_FLAG_VLPF) {
int srcp_linesize = src_linesize[plane] * k;
int dstp_linesize = dst_linesize[plane] * (interleave ? 2 : 1);
for (h = lines; h > 0; h--) {
ptrdiff_t pref = src_linesize[plane];
ptrdiff_t mref = -pref;
if (h == lines) mref = 0; // there is no line above
else if (h == 1) pref = 0; // there is no line below
tinterlace->lowpass_line(dstp, cols, srcp, mref, pref);
dstp += dstp_linesize;
srcp += srcp_linesize;
}
} else {
av_image_copy_plane(dstp, dst_linesize[plane] * (interleave ? 2 : 1),
srcp, src_linesize[plane]*k, cols, lines);
}
}
}
static int filter_frame(AVFilterLink *inlink, AVFrame *picref)
{
AVFilterContext *ctx = inlink->dst;
AVFilterLink *outlink = ctx->outputs[0];
TInterlaceContext *tinterlace = ctx->priv;
AVFrame *cur, *next, *out;
int field, tff, ret;
av_frame_free(&tinterlace->cur);
tinterlace->cur = tinterlace->next;
tinterlace->next = picref;
cur = tinterlace->cur;
next = tinterlace->next;
/* we need at least two frames */
if (!tinterlace->cur)
return 0;
switch (tinterlace->mode) {
case MODE_MERGEX2: /* move the odd frame into the upper field of the new image, even into
* the lower field, generating a double-height video at same framerate */
case MODE_MERGE: /* move the odd frame into the upper field of the new image, even into
* the lower field, generating a double-height video at half framerate */
out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
if (!out)
return AVERROR(ENOMEM);
av_frame_copy_props(out, cur);
out->height = outlink->h;
out->interlaced_frame = 1;
out->top_field_first = 1;
out->sample_aspect_ratio = av_mul_q(cur->sample_aspect_ratio, av_make_q(2, 1));
/* write odd frame lines into the upper field of the new frame */
copy_picture_field(tinterlace, out->data, out->linesize,
(const uint8_t **)cur->data, cur->linesize,
inlink->format, inlink->w, inlink->h,
FIELD_UPPER_AND_LOWER, 1, tinterlace->mode == MODE_MERGEX2 ? inlink->frame_count_out & 1 ? FIELD_LOWER : FIELD_UPPER : FIELD_UPPER, tinterlace->flags);
/* write even frame lines into the lower field of the new frame */
copy_picture_field(tinterlace, out->data, out->linesize,
(const uint8_t **)next->data, next->linesize,
inlink->format, inlink->w, inlink->h,
FIELD_UPPER_AND_LOWER, 1, tinterlace->mode == MODE_MERGEX2 ? inlink->frame_count_out & 1 ? FIELD_UPPER : FIELD_LOWER : FIELD_LOWER, tinterlace->flags);
if (tinterlace->mode != MODE_MERGEX2)
av_frame_free(&tinterlace->next);
break;
case MODE_DROP_ODD: /* only output even frames, odd frames are dropped; height unchanged, half framerate */
case MODE_DROP_EVEN: /* only output odd frames, even frames are dropped; height unchanged, half framerate */
out = av_frame_clone(tinterlace->mode == MODE_DROP_EVEN ? cur : next);
if (!out)
return AVERROR(ENOMEM);
av_frame_free(&tinterlace->next);
break;
case MODE_PAD: /* expand each frame to double height, but pad alternate
* lines with black; framerate unchanged */
out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
if (!out)
return AVERROR(ENOMEM);
av_frame_copy_props(out, cur);
out->height = outlink->h;
out->sample_aspect_ratio = av_mul_q(cur->sample_aspect_ratio, av_make_q(2, 1));
field = (1 + tinterlace->frame) & 1 ? FIELD_UPPER : FIELD_LOWER;
/* copy upper and lower fields */
copy_picture_field(tinterlace, out->data, out->linesize,
(const uint8_t **)cur->data, cur->linesize,
inlink->format, inlink->w, inlink->h,
FIELD_UPPER_AND_LOWER, 1, field, tinterlace->flags);
/* pad with black the other field */
copy_picture_field(tinterlace, 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, tinterlace->flags);
break;
/* interleave upper/lower lines from odd frames with lower/upper lines from even frames,
* halving the frame rate and preserving image height */
case MODE_INTERLEAVE_TOP: /* top field first */
case MODE_INTERLEAVE_BOTTOM: /* bottom field first */
tff = tinterlace->mode == MODE_INTERLEAVE_TOP;
out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
if (!out)
return AVERROR(ENOMEM);
av_frame_copy_props(out, cur);
out->interlaced_frame = 1;
out->top_field_first = tff;
/* copy upper/lower field from cur */
copy_picture_field(tinterlace, 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,
tinterlace->flags);
/* copy lower/upper field from next */
copy_picture_field(tinterlace, 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,
tinterlace->flags);
av_frame_free(&tinterlace->next);
break;
case MODE_INTERLACEX2: /* re-interlace preserving image height, double frame rate */
/* output current frame first */
out = av_frame_clone(cur);
if (!out)
return AVERROR(ENOMEM);
out->interlaced_frame = 1;
if (cur->pts != AV_NOPTS_VALUE)
out->pts = cur->pts*2;
out->pts = av_rescale_q(out->pts, tinterlace->preout_time_base, outlink->time_base);
if ((ret = ff_filter_frame(outlink, out)) < 0)
return ret;
/* output mix of current and next frame */
tff = next->top_field_first;
out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
if (!out)
return AVERROR(ENOMEM);
av_frame_copy_props(out, next);
out->interlaced_frame = 1;
out->top_field_first = !tff;
if (next->pts != AV_NOPTS_VALUE && cur->pts != AV_NOPTS_VALUE)
out->pts = cur->pts + next->pts;
else
out->pts = AV_NOPTS_VALUE;
/* write current frame second field lines into the second field of the new frame */
copy_picture_field(tinterlace, 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,
tinterlace->flags);
/* write next frame first field lines into the first field of the new frame */
copy_picture_field(tinterlace, 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,
tinterlace->flags);
break;
default:
av_assert0(0);
}
out->pts = av_rescale_q(out->pts, tinterlace->preout_time_base, outlink->time_base);
ret = ff_filter_frame(outlink, out);
tinterlace->frame++;
return ret;
}
static const AVFilterPad tinterlace_inputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.filter_frame = filter_frame,
},
{ NULL }
};
static const AVFilterPad tinterlace_outputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.config_props = config_out_props,
},
{ NULL }
};
AVFilter ff_vf_tinterlace = {
.name = "tinterlace",
.description = NULL_IF_CONFIG_SMALL("Perform temporal field interlacing."),
.priv_size = sizeof(TInterlaceContext),
.uninit = uninit,
.query_formats = query_formats,
.inputs = tinterlace_inputs,
.outputs = tinterlace_outputs,
.priv_class = &tinterlace_class,
};
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