diff options
Diffstat (limited to 'libavfilter/scale.c')
| -rw-r--r-- | libavfilter/scale.c | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/libavfilter/scale.c b/libavfilter/scale.c new file mode 100644 index 0000000000..50cd442849 --- /dev/null +++ b/libavfilter/scale.c @@ -0,0 +1,152 @@ +/* + * 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 +}; + +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; + double var_values[VARS_NB], res; + + 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; + + /* evaluate width and height */ + av_expr_parse_and_eval(&res, (expr = w_expr), + var_names, var_values, + 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), + var_names, var_values, + 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), + var_names, var_values, + 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; +} |