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FFmpeg/libavfilter/scale.c

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avfilter/scale: refactor common code for scaling height/width expressions Implements support for height/width expressions in vf_scale_vaapi, by refactoring common code into a new libavfilter/scale.c Signed-off-by: Mark Thompson <sw@jkqxz.net>
8 years ago
/*
* Copyright (c) 2007 Bobby Bingham
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser 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
*/
#include <stdint.h>
#include "scale.h"
#include "libavutil/eval.h"
#include "libavutil/mathematics.h"
#include "libavutil/pixdesc.h"
static const char *const var_names[] = {
"PI",
"PHI",
"E",
"in_w", "iw",
"in_h", "ih",
"out_w", "ow",
"out_h", "oh",
"a",
"sar",
"dar",
"hsub",
"vsub",
"ohsub",
"ovsub",
NULL
};
enum var_name {
VAR_PI,
VAR_PHI,
VAR_E,
VAR_IN_W, VAR_IW,
VAR_IN_H, VAR_IH,
VAR_OUT_W, VAR_OW,
VAR_OUT_H, VAR_OH,
VAR_A,
VAR_SAR,
VAR_DAR,
VAR_HSUB,
VAR_VSUB,
VAR_OHSUB,
VAR_OVSUB,
VARS_NB
};
libavfilter/scale2ref: Add constants for the primary input Variables pertaining to the main video are now available when using the scale2ref filter. This allows, as an example, scaling a video with another as a reference point while maintaining the original aspect ratio of the primary/non-reference video. Consider the following graph: scale2ref=iw/6:-1 [main][ref] This will scale [main] to 1/6 the width of [ref] while maintaining the aspect ratio. This works well when the AR of [ref] is equal to the AR of [main] only. What the above filter really does is maintain the AR of [ref] when scaling [main]. So in all non-same-AR situations [main] will appear stretched or compressed to conform to the same AR of the reference video. Without doing this calculation externally there is no way to scale in reference to another input while maintaining AR in libavfilter. To make this possible, we introduce eight new constants to be used in the w and h expressions only in the scale2ref filter: * main_w/main_h: width/height of the main input video * main_a: aspect ratio of the main input video * main_sar: sample aspect ratio of the main input video * main_dar: display aspect ratio of the main input video * main_hsub/main_vsub: horiz/vert chroma subsample vals of main * mdar: a shorthand alias of main_dar Of course, not all of these constants are needed for maintaining the AR, but adding additional constants in line of what is available for in/out allows for other scaling possibilities I have not imagined. So to now scale a video to 1/6 the size of another video using the width and maintaining its own aspect ratio you can do this: scale2ref=iw/6:ow/mdar [main][ref] This is ideal for picture-in-picture configurations where you could have a square or 4:3 video overlaid on a corner of a larger 16:9 feed all while keeping the scaled video in the corner at its correct aspect ratio and always the same size relative to the larger video. I've tried to re-use as much code as possible. I could not find a way to avoid duplication of the var_names array. It must now be kept in sync with the other (the normal one and the scale2ref one) for everything to work which does not seem ideal. For every new variable introduced/removed into/from the normal scale filter one must be added/removed to/from the scale2ref version. Suggestions on how to avoid var_names duplication are welcome. var_values has been increased to always be large enough for the additional scale2ref variables. I do not forsee this being a problem as the names variable will always be the correct size. From my understanding of av_expr_parse_and_eval it will stop processing variables when it runs out of names even though there may be additional (potentially uninitialized) entries in the values array. The ideal solution here would be using a variable-length array but that is unsupported in C90. This patch does not remove any functionality and is strictly a feature patch. There are no API changes. Behavior does not change for any previously valid inputs. The applicable documentation has also been updated. Signed-off-by: Kevin Mark <kmark937@gmail.com> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
8 years ago
/**
* This must be kept in sync with var_names so that it is always a
* complete list of var_names with the scale2ref specific names
* appended. scale2ref values must appear in the order they appear
* in the var_name_scale2ref enum but also be below all of the
* non-scale2ref specific values.
*/
static const char *const var_names_scale2ref[] = {
"PI",
"PHI",
"E",
"in_w", "iw",
"in_h", "ih",
"out_w", "ow",
"out_h", "oh",
"a",
"sar",
"dar",
"hsub",
"vsub",
"ohsub",
"ovsub",
"main_w",
"main_h",
"main_a",
"main_sar",
"main_dar", "mdar",
"main_hsub",
"main_vsub",
NULL
};
enum var_name_scale2ref {
VAR_S2R_MAIN_W,
VAR_S2R_MAIN_H,
VAR_S2R_MAIN_A,
VAR_S2R_MAIN_SAR,
VAR_S2R_MAIN_DAR, VAR_S2R_MDAR,
VAR_S2R_MAIN_HSUB,
VAR_S2R_MAIN_VSUB,
VARS_S2R_NB
};
avfilter/scale: refactor common code for scaling height/width expressions Implements support for height/width expressions in vf_scale_vaapi, by refactoring common code into a new libavfilter/scale.c Signed-off-by: Mark Thompson <sw@jkqxz.net>
8 years ago
int ff_scale_eval_dimensions(void *log_ctx,
const char *w_expr, const char *h_expr,
AVFilterLink *inlink, AVFilterLink *outlink,
int *ret_w, int *ret_h)
{
const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
const AVPixFmtDescriptor *out_desc = av_pix_fmt_desc_get(outlink->format);
const char *expr;
int w, h;
int factor_w, factor_h;
int eval_w, eval_h;
int ret;
libavfilter/scale2ref: Fix out-of-bounds array access ff_scale_eval_dimensions blindly assumes that two inputs are always available as of 3385989b98be7940044e4f0a6b431a0a00abf2fa. This is notably not the case when the function is called for the scale filter. With the scale filter inputs[1] does not exist. ff_scale_eval_dimensions now has an updated scale2ref check that makes certain two inputs are actually available before attempting to access the second one. Thanks to James Almer for reporting this bug. This should fix the 820 Valgrind tests I single-handedly managed to break. Signed-off-by: Kevin Mark <kmark937@gmail.com> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
8 years ago
const char scale2ref = outlink->src->nb_inputs == 2 && outlink->src->inputs[1] == inlink;
libavfilter/scale2ref: Add constants for the primary input Variables pertaining to the main video are now available when using the scale2ref filter. This allows, as an example, scaling a video with another as a reference point while maintaining the original aspect ratio of the primary/non-reference video. Consider the following graph: scale2ref=iw/6:-1 [main][ref] This will scale [main] to 1/6 the width of [ref] while maintaining the aspect ratio. This works well when the AR of [ref] is equal to the AR of [main] only. What the above filter really does is maintain the AR of [ref] when scaling [main]. So in all non-same-AR situations [main] will appear stretched or compressed to conform to the same AR of the reference video. Without doing this calculation externally there is no way to scale in reference to another input while maintaining AR in libavfilter. To make this possible, we introduce eight new constants to be used in the w and h expressions only in the scale2ref filter: * main_w/main_h: width/height of the main input video * main_a: aspect ratio of the main input video * main_sar: sample aspect ratio of the main input video * main_dar: display aspect ratio of the main input video * main_hsub/main_vsub: horiz/vert chroma subsample vals of main * mdar: a shorthand alias of main_dar Of course, not all of these constants are needed for maintaining the AR, but adding additional constants in line of what is available for in/out allows for other scaling possibilities I have not imagined. So to now scale a video to 1/6 the size of another video using the width and maintaining its own aspect ratio you can do this: scale2ref=iw/6:ow/mdar [main][ref] This is ideal for picture-in-picture configurations where you could have a square or 4:3 video overlaid on a corner of a larger 16:9 feed all while keeping the scaled video in the corner at its correct aspect ratio and always the same size relative to the larger video. I've tried to re-use as much code as possible. I could not find a way to avoid duplication of the var_names array. It must now be kept in sync with the other (the normal one and the scale2ref one) for everything to work which does not seem ideal. For every new variable introduced/removed into/from the normal scale filter one must be added/removed to/from the scale2ref version. Suggestions on how to avoid var_names duplication are welcome. var_values has been increased to always be large enough for the additional scale2ref variables. I do not forsee this being a problem as the names variable will always be the correct size. From my understanding of av_expr_parse_and_eval it will stop processing variables when it runs out of names even though there may be additional (potentially uninitialized) entries in the values array. The ideal solution here would be using a variable-length array but that is unsupported in C90. This patch does not remove any functionality and is strictly a feature patch. There are no API changes. Behavior does not change for any previously valid inputs. The applicable documentation has also been updated. Signed-off-by: Kevin Mark <kmark937@gmail.com> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
8 years ago
double var_values[VARS_NB + VARS_S2R_NB], res;
const AVPixFmtDescriptor *main_desc;
const AVFilterLink *main_link;
const char *const *names = scale2ref ? var_names_scale2ref : var_names;
if (scale2ref) {
main_link = outlink->src->inputs[0];
main_desc = av_pix_fmt_desc_get(main_link->format);
}
avfilter/scale: refactor common code for scaling height/width expressions Implements support for height/width expressions in vf_scale_vaapi, by refactoring common code into a new libavfilter/scale.c Signed-off-by: Mark Thompson <sw@jkqxz.net>
8 years ago
var_values[VAR_PI] = M_PI;
var_values[VAR_PHI] = M_PHI;
var_values[VAR_E] = M_E;
var_values[VAR_IN_W] = var_values[VAR_IW] = inlink->w;
var_values[VAR_IN_H] = var_values[VAR_IH] = inlink->h;
var_values[VAR_OUT_W] = var_values[VAR_OW] = NAN;
var_values[VAR_OUT_H] = var_values[VAR_OH] = NAN;
var_values[VAR_A] = (double) inlink->w / inlink->h;
var_values[VAR_SAR] = inlink->sample_aspect_ratio.num ?
(double) inlink->sample_aspect_ratio.num / inlink->sample_aspect_ratio.den : 1;
var_values[VAR_DAR] = var_values[VAR_A] * var_values[VAR_SAR];
var_values[VAR_HSUB] = 1 << desc->log2_chroma_w;
var_values[VAR_VSUB] = 1 << desc->log2_chroma_h;
var_values[VAR_OHSUB] = 1 << out_desc->log2_chroma_w;
var_values[VAR_OVSUB] = 1 << out_desc->log2_chroma_h;
libavfilter/scale2ref: Add constants for the primary input Variables pertaining to the main video are now available when using the scale2ref filter. This allows, as an example, scaling a video with another as a reference point while maintaining the original aspect ratio of the primary/non-reference video. Consider the following graph: scale2ref=iw/6:-1 [main][ref] This will scale [main] to 1/6 the width of [ref] while maintaining the aspect ratio. This works well when the AR of [ref] is equal to the AR of [main] only. What the above filter really does is maintain the AR of [ref] when scaling [main]. So in all non-same-AR situations [main] will appear stretched or compressed to conform to the same AR of the reference video. Without doing this calculation externally there is no way to scale in reference to another input while maintaining AR in libavfilter. To make this possible, we introduce eight new constants to be used in the w and h expressions only in the scale2ref filter: * main_w/main_h: width/height of the main input video * main_a: aspect ratio of the main input video * main_sar: sample aspect ratio of the main input video * main_dar: display aspect ratio of the main input video * main_hsub/main_vsub: horiz/vert chroma subsample vals of main * mdar: a shorthand alias of main_dar Of course, not all of these constants are needed for maintaining the AR, but adding additional constants in line of what is available for in/out allows for other scaling possibilities I have not imagined. So to now scale a video to 1/6 the size of another video using the width and maintaining its own aspect ratio you can do this: scale2ref=iw/6:ow/mdar [main][ref] This is ideal for picture-in-picture configurations where you could have a square or 4:3 video overlaid on a corner of a larger 16:9 feed all while keeping the scaled video in the corner at its correct aspect ratio and always the same size relative to the larger video. I've tried to re-use as much code as possible. I could not find a way to avoid duplication of the var_names array. It must now be kept in sync with the other (the normal one and the scale2ref one) for everything to work which does not seem ideal. For every new variable introduced/removed into/from the normal scale filter one must be added/removed to/from the scale2ref version. Suggestions on how to avoid var_names duplication are welcome. var_values has been increased to always be large enough for the additional scale2ref variables. I do not forsee this being a problem as the names variable will always be the correct size. From my understanding of av_expr_parse_and_eval it will stop processing variables when it runs out of names even though there may be additional (potentially uninitialized) entries in the values array. The ideal solution here would be using a variable-length array but that is unsupported in C90. This patch does not remove any functionality and is strictly a feature patch. There are no API changes. Behavior does not change for any previously valid inputs. The applicable documentation has also been updated. Signed-off-by: Kevin Mark <kmark937@gmail.com> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
8 years ago
if (scale2ref) {
var_values[VARS_NB + VAR_S2R_MAIN_W] = main_link->w;
var_values[VARS_NB + VAR_S2R_MAIN_H] = main_link->h;
var_values[VARS_NB + VAR_S2R_MAIN_A] = (double) main_link->w / main_link->h;
var_values[VARS_NB + VAR_S2R_MAIN_SAR] = main_link->sample_aspect_ratio.num ?
(double) main_link->sample_aspect_ratio.num / main_link->sample_aspect_ratio.den : 1;
var_values[VARS_NB + VAR_S2R_MAIN_DAR] = var_values[VARS_NB + VAR_S2R_MDAR] =
var_values[VARS_NB + VAR_S2R_MAIN_A] * var_values[VARS_NB + VAR_S2R_MAIN_SAR];
var_values[VARS_NB + VAR_S2R_MAIN_HSUB] = 1 << main_desc->log2_chroma_w;
var_values[VARS_NB + VAR_S2R_MAIN_VSUB] = 1 << main_desc->log2_chroma_h;
}
avfilter/scale: refactor common code for scaling height/width expressions Implements support for height/width expressions in vf_scale_vaapi, by refactoring common code into a new libavfilter/scale.c Signed-off-by: Mark Thompson <sw@jkqxz.net>
8 years ago
/* evaluate width and height */
av_expr_parse_and_eval(&res, (expr = w_expr),
libavfilter/scale2ref: Add constants for the primary input Variables pertaining to the main video are now available when using the scale2ref filter. This allows, as an example, scaling a video with another as a reference point while maintaining the original aspect ratio of the primary/non-reference video. Consider the following graph: scale2ref=iw/6:-1 [main][ref] This will scale [main] to 1/6 the width of [ref] while maintaining the aspect ratio. This works well when the AR of [ref] is equal to the AR of [main] only. What the above filter really does is maintain the AR of [ref] when scaling [main]. So in all non-same-AR situations [main] will appear stretched or compressed to conform to the same AR of the reference video. Without doing this calculation externally there is no way to scale in reference to another input while maintaining AR in libavfilter. To make this possible, we introduce eight new constants to be used in the w and h expressions only in the scale2ref filter: * main_w/main_h: width/height of the main input video * main_a: aspect ratio of the main input video * main_sar: sample aspect ratio of the main input video * main_dar: display aspect ratio of the main input video * main_hsub/main_vsub: horiz/vert chroma subsample vals of main * mdar: a shorthand alias of main_dar Of course, not all of these constants are needed for maintaining the AR, but adding additional constants in line of what is available for in/out allows for other scaling possibilities I have not imagined. So to now scale a video to 1/6 the size of another video using the width and maintaining its own aspect ratio you can do this: scale2ref=iw/6:ow/mdar [main][ref] This is ideal for picture-in-picture configurations where you could have a square or 4:3 video overlaid on a corner of a larger 16:9 feed all while keeping the scaled video in the corner at its correct aspect ratio and always the same size relative to the larger video. I've tried to re-use as much code as possible. I could not find a way to avoid duplication of the var_names array. It must now be kept in sync with the other (the normal one and the scale2ref one) for everything to work which does not seem ideal. For every new variable introduced/removed into/from the normal scale filter one must be added/removed to/from the scale2ref version. Suggestions on how to avoid var_names duplication are welcome. var_values has been increased to always be large enough for the additional scale2ref variables. I do not forsee this being a problem as the names variable will always be the correct size. From my understanding of av_expr_parse_and_eval it will stop processing variables when it runs out of names even though there may be additional (potentially uninitialized) entries in the values array. The ideal solution here would be using a variable-length array but that is unsupported in C90. This patch does not remove any functionality and is strictly a feature patch. There are no API changes. Behavior does not change for any previously valid inputs. The applicable documentation has also been updated. Signed-off-by: Kevin Mark <kmark937@gmail.com> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
8 years ago
names, var_values,
avfilter/scale: refactor common code for scaling height/width expressions Implements support for height/width expressions in vf_scale_vaapi, by refactoring common code into a new libavfilter/scale.c Signed-off-by: Mark Thompson <sw@jkqxz.net>
8 years ago
NULL, NULL, NULL, NULL, NULL, 0, log_ctx);
eval_w = var_values[VAR_OUT_W] = var_values[VAR_OW] = res;
if ((ret = av_expr_parse_and_eval(&res, (expr = h_expr),
libavfilter/scale2ref: Add constants for the primary input Variables pertaining to the main video are now available when using the scale2ref filter. This allows, as an example, scaling a video with another as a reference point while maintaining the original aspect ratio of the primary/non-reference video. Consider the following graph: scale2ref=iw/6:-1 [main][ref] This will scale [main] to 1/6 the width of [ref] while maintaining the aspect ratio. This works well when the AR of [ref] is equal to the AR of [main] only. What the above filter really does is maintain the AR of [ref] when scaling [main]. So in all non-same-AR situations [main] will appear stretched or compressed to conform to the same AR of the reference video. Without doing this calculation externally there is no way to scale in reference to another input while maintaining AR in libavfilter. To make this possible, we introduce eight new constants to be used in the w and h expressions only in the scale2ref filter: * main_w/main_h: width/height of the main input video * main_a: aspect ratio of the main input video * main_sar: sample aspect ratio of the main input video * main_dar: display aspect ratio of the main input video * main_hsub/main_vsub: horiz/vert chroma subsample vals of main * mdar: a shorthand alias of main_dar Of course, not all of these constants are needed for maintaining the AR, but adding additional constants in line of what is available for in/out allows for other scaling possibilities I have not imagined. So to now scale a video to 1/6 the size of another video using the width and maintaining its own aspect ratio you can do this: scale2ref=iw/6:ow/mdar [main][ref] This is ideal for picture-in-picture configurations where you could have a square or 4:3 video overlaid on a corner of a larger 16:9 feed all while keeping the scaled video in the corner at its correct aspect ratio and always the same size relative to the larger video. I've tried to re-use as much code as possible. I could not find a way to avoid duplication of the var_names array. It must now be kept in sync with the other (the normal one and the scale2ref one) for everything to work which does not seem ideal. For every new variable introduced/removed into/from the normal scale filter one must be added/removed to/from the scale2ref version. Suggestions on how to avoid var_names duplication are welcome. var_values has been increased to always be large enough for the additional scale2ref variables. I do not forsee this being a problem as the names variable will always be the correct size. From my understanding of av_expr_parse_and_eval it will stop processing variables when it runs out of names even though there may be additional (potentially uninitialized) entries in the values array. The ideal solution here would be using a variable-length array but that is unsupported in C90. This patch does not remove any functionality and is strictly a feature patch. There are no API changes. Behavior does not change for any previously valid inputs. The applicable documentation has also been updated. Signed-off-by: Kevin Mark <kmark937@gmail.com> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
8 years ago
names, var_values,
avfilter/scale: refactor common code for scaling height/width expressions Implements support for height/width expressions in vf_scale_vaapi, by refactoring common code into a new libavfilter/scale.c Signed-off-by: Mark Thompson <sw@jkqxz.net>
8 years ago
NULL, NULL, NULL, NULL, NULL, 0, log_ctx)) < 0)
goto fail;
eval_h = var_values[VAR_OUT_H] = var_values[VAR_OH] = res;
/* evaluate again the width, as it may depend on the output height */
if ((ret = av_expr_parse_and_eval(&res, (expr = w_expr),
libavfilter/scale2ref: Add constants for the primary input Variables pertaining to the main video are now available when using the scale2ref filter. This allows, as an example, scaling a video with another as a reference point while maintaining the original aspect ratio of the primary/non-reference video. Consider the following graph: scale2ref=iw/6:-1 [main][ref] This will scale [main] to 1/6 the width of [ref] while maintaining the aspect ratio. This works well when the AR of [ref] is equal to the AR of [main] only. What the above filter really does is maintain the AR of [ref] when scaling [main]. So in all non-same-AR situations [main] will appear stretched or compressed to conform to the same AR of the reference video. Without doing this calculation externally there is no way to scale in reference to another input while maintaining AR in libavfilter. To make this possible, we introduce eight new constants to be used in the w and h expressions only in the scale2ref filter: * main_w/main_h: width/height of the main input video * main_a: aspect ratio of the main input video * main_sar: sample aspect ratio of the main input video * main_dar: display aspect ratio of the main input video * main_hsub/main_vsub: horiz/vert chroma subsample vals of main * mdar: a shorthand alias of main_dar Of course, not all of these constants are needed for maintaining the AR, but adding additional constants in line of what is available for in/out allows for other scaling possibilities I have not imagined. So to now scale a video to 1/6 the size of another video using the width and maintaining its own aspect ratio you can do this: scale2ref=iw/6:ow/mdar [main][ref] This is ideal for picture-in-picture configurations where you could have a square or 4:3 video overlaid on a corner of a larger 16:9 feed all while keeping the scaled video in the corner at its correct aspect ratio and always the same size relative to the larger video. I've tried to re-use as much code as possible. I could not find a way to avoid duplication of the var_names array. It must now be kept in sync with the other (the normal one and the scale2ref one) for everything to work which does not seem ideal. For every new variable introduced/removed into/from the normal scale filter one must be added/removed to/from the scale2ref version. Suggestions on how to avoid var_names duplication are welcome. var_values has been increased to always be large enough for the additional scale2ref variables. I do not forsee this being a problem as the names variable will always be the correct size. From my understanding of av_expr_parse_and_eval it will stop processing variables when it runs out of names even though there may be additional (potentially uninitialized) entries in the values array. The ideal solution here would be using a variable-length array but that is unsupported in C90. This patch does not remove any functionality and is strictly a feature patch. There are no API changes. Behavior does not change for any previously valid inputs. The applicable documentation has also been updated. Signed-off-by: Kevin Mark <kmark937@gmail.com> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
8 years ago
names, var_values,
avfilter/scale: refactor common code for scaling height/width expressions Implements support for height/width expressions in vf_scale_vaapi, by refactoring common code into a new libavfilter/scale.c Signed-off-by: Mark Thompson <sw@jkqxz.net>
8 years ago
NULL, NULL, NULL, NULL, NULL, 0, log_ctx)) < 0)
goto fail;
eval_w = res;
w = eval_w;
h = eval_h;
/* Check if it is requested that the result has to be divisible by a some
* factor (w or h = -n with n being the factor). */
factor_w = 1;
factor_h = 1;
if (w < -1) {
factor_w = -w;
}
if (h < -1) {
factor_h = -h;
}
if (w < 0 && h < 0)
eval_w = eval_h = 0;
if (!(w = eval_w))
w = inlink->w;
if (!(h = eval_h))
h = inlink->h;
/* Make sure that the result is divisible by the factor we determined
* earlier. If no factor was set, it is nothing will happen as the default
* factor is 1 */
if (w < 0)
w = av_rescale(h, inlink->w, inlink->h * factor_w) * factor_w;
if (h < 0)
h = av_rescale(w, inlink->h, inlink->w * factor_h) * factor_h;
*ret_w = w;
*ret_h = h;
return 0;
fail:
av_log(log_ctx, AV_LOG_ERROR,
"Error when evaluating the expression '%s'.\n"
"Maybe the expression for out_w:'%s' or for out_h:'%s' is self-referencing.\n",
expr, w_expr, h_expr);
return ret;
}