mirror of https://git.ffmpeg.org/ffmpeg.git
scale: make the filter parametric
Make the filter accept parametric expressions for the output video size. Signed-off-by: Stefano Sabatini <stefano.sabatini-lala@poste.it> Signed-off-by: Anton Khirnov <anton@khirnov.net>
This commit is contained in:
Stefano Sabatini
Anton Khirnov
parent
b137bf7df3
commit
68e23c083a
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@ -772,13 +772,33 @@ can be used to test the monowhite pixel format descriptor definition.
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Scale the input video to @var{width}:@var{height} and/or convert the image format.
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For example the command:
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The parameters @var{width} and @var{height} are expressions containing
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the following constants:
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@example
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./ffmpeg -i in.avi -vf "scale=200:100" out.avi
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@end example
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@table @option
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@item E, PI, PHI
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the corresponding mathematical approximated values for e
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(euler number), pi (greek PI), phi (golden ratio)
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will scale the input video to a size of 200x100.
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@item in_w, in_h
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the input width and heigth
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@item iw, ih
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same as @var{in_w} and @var{in_h}
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@item out_w, out_h
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the output (cropped) width and heigth
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@item ow, oh
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same as @var{out_w} and @var{out_h}
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@item a
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input display aspect ratio, same as @var{iw} / @var{ih}
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@item hsub, vsub
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horizontal and vertical chroma subsample values. For example for the
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pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
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@end table
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If the input image format is different from the format requested by
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the next filter, the scale filter will convert the input to the
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@ -793,6 +813,36 @@ ratio of the input image.
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The default value of @var{width} and @var{height} is 0.
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Some examples follow:
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@example
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# scale the input video to a size of 200x100.
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scale=200:100
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# scale the input to 2x
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scale=2*iw:2*ih
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# the above is the same as
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scale=2*in_w:2*in_h
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# scale the input to half size
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scale=iw/2:ih/2
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# increase the width, and set the height to the same size
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scale=3/2*iw:ow
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# seek for Greek harmony
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scale=iw:1/PHI*iw
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scale=ih*PHI:ih
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# increase the height, and set the width to 3/2 of the height
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scale=3/2*oh:3/5*ih
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# increase the size, but make the size a multiple of the chroma
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scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
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# increase the width to a maximum of 500 pixels, keep the same input aspect ratio
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scale='min(500\, iw*3/2):-1'
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@end example
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@anchor{setdar}
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@section setdar
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@ -24,9 +24,39 @@
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*/
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#include "avfilter.h"
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#include "libavutil/avstring.h"
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#include "libavutil/eval.h"
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#include "libavutil/pixdesc.h"
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#include "libswscale/swscale.h"
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static const char *var_names[] = {
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"PI",
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"PHI",
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"E",
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"in_w", "iw",
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"in_h", "ih",
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"out_w", "ow",
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"out_h", "oh",
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"a",
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"hsub",
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"vsub",
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NULL
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};
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enum var_name {
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VAR_PI,
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VAR_PHI,
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VAR_E,
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VAR_IN_W, VAR_IW,
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VAR_IN_H, VAR_IH,
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VAR_OUT_W, VAR_OW,
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VAR_OUT_H, VAR_OH,
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VAR_A,
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VAR_HSUB,
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VAR_VSUB,
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VARS_NB
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};
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typedef struct {
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struct SwsContext *sws; ///< software scaler context
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@ -41,6 +71,9 @@ typedef struct {
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int hsub, vsub; ///< chroma subsampling
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int slice_y; ///< top of current output slice
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int input_is_pal; ///< set to 1 if the input format is paletted
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char w_expr[256]; ///< width expression string
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char h_expr[256]; ///< height expression string
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} ScaleContext;
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static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
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@ -48,21 +81,16 @@ static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
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ScaleContext *scale = ctx->priv;
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const char *p;
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av_strlcpy(scale->w_expr, "iw", sizeof(scale->w_expr));
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av_strlcpy(scale->h_expr, "ih", sizeof(scale->h_expr));
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scale->flags = SWS_BILINEAR;
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if (args) {
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sscanf(args, "%d:%d", &scale->w, &scale->h);
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sscanf(args, "%255[^:]:%255[^:]", scale->w_expr, scale->h_expr);
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p = strstr(args,"flags=");
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if (p) scale->flags = strtoul(p+6, NULL, 0);
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}
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/* sanity check params */
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if (scale->w < -1 || scale->h < -1) {
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av_log(ctx, AV_LOG_ERROR, "Size values less than -1 are not acceptable.\n");
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return AVERROR(EINVAL);
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}
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if (scale->w == -1 && scale->h == -1)
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scale->w = scale->h = 0;
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return 0;
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}
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@ -109,6 +137,48 @@ static int config_props(AVFilterLink *outlink)
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AVFilterLink *inlink = outlink->src->inputs[0];
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ScaleContext *scale = ctx->priv;
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int64_t w, h;
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double var_values[VARS_NB], res;
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char *expr;
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int ret;
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var_values[VAR_PI] = M_PI;
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var_values[VAR_PHI] = M_PHI;
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var_values[VAR_E] = M_E;
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var_values[VAR_IN_W] = var_values[VAR_IW] = inlink->w;
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var_values[VAR_IN_H] = var_values[VAR_IH] = inlink->h;
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var_values[VAR_OUT_W] = var_values[VAR_OW] = NAN;
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var_values[VAR_OUT_H] = var_values[VAR_OH] = NAN;
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var_values[VAR_A] = (float) inlink->w / inlink->h;
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var_values[VAR_HSUB] = 1<<av_pix_fmt_descriptors[inlink->format].log2_chroma_w;
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var_values[VAR_VSUB] = 1<<av_pix_fmt_descriptors[inlink->format].log2_chroma_h;
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/* evaluate width and height */
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av_expr_parse_and_eval(&res, (expr = scale->w_expr),
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var_names, var_values,
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NULL, NULL, NULL, NULL, NULL, 0, ctx);
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scale->w = var_values[VAR_OUT_W] = var_values[VAR_OW] = res;
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if ((ret = av_expr_parse_and_eval(&res, (expr = scale->h_expr),
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var_names, var_values,
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NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
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goto fail;
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scale->h = var_values[VAR_OUT_H] = var_values[VAR_OH] = res;
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/* evaluate again the width, as it may depend on the output height */
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if ((ret = av_expr_parse_and_eval(&res, (expr = scale->w_expr),
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var_names, var_values,
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NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
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goto fail;
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scale->w = res;
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w = scale->w;
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h = scale->h;
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/* sanity check params */
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if (w < -1 || h < -1) {
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av_log(ctx, AV_LOG_ERROR, "Size values less than -1 are not acceptable.\n");
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return AVERROR(EINVAL);
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}
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if (w == -1 && h == -1)
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scale->w = scale->h = 0;
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if (!(w = scale->w))
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w = inlink->w;
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@ -142,6 +212,11 @@ static int config_props(AVFilterLink *outlink)
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return AVERROR(EINVAL);
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return 0;
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fail:
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av_log(NULL, AV_LOG_ERROR,
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"Error when evaluating the expression '%s'\n", expr);
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return ret;
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}
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static void start_frame(AVFilterLink *link, AVFilterBufferRef *picref)
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