diff options
| -rw-r--r-- | doc/filters.texi | 60 | ||||
| -rw-r--r-- | libavfilter/vf_scale.c | 93 |
2 files changed, 139 insertions, 14 deletions
diff --git a/doc/filters.texi b/doc/filters.texi index 1a26f10c59..669a334eca 100644 --- a/doc/filters.texi +++ b/doc/filters.texi @@ -772,13 +772,33 @@ can be used to test the monowhite pixel format descriptor definition. Scale the input video to @var{width}:@var{height} and/or convert the image format. -For example the command: +The parameters @var{width} and @var{height} are expressions containing +the following constants: -@example -./ffmpeg -i in.avi -vf "scale=200:100" out.avi -@end example +@table @option +@item E, PI, PHI +the corresponding mathematical approximated values for e +(euler number), pi (greek PI), phi (golden ratio) + +@item in_w, in_h +the input width and heigth + +@item iw, ih +same as @var{in_w} and @var{in_h} + +@item out_w, out_h +the output (cropped) width and heigth + +@item ow, oh +same as @var{out_w} and @var{out_h} -will scale the input video to a size of 200x100. +@item a +input display aspect ratio, same as @var{iw} / @var{ih} + +@item hsub, vsub +horizontal and vertical chroma subsample values. For example for the +pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. +@end table If the input image format is different from the format requested by the next filter, the scale filter will convert the input to the @@ -793,6 +813,36 @@ ratio of the input image. The default value of @var{width} and @var{height} is 0. +Some examples follow: +@example +# scale the input video to a size of 200x100. +scale=200:100 + +# scale the input to 2x +scale=2*iw:2*ih +# the above is the same as +scale=2*in_w:2*in_h + +# scale the input to half size +scale=iw/2:ih/2 + +# increase the width, and set the height to the same size +scale=3/2*iw:ow + +# seek for Greek harmony +scale=iw:1/PHI*iw +scale=ih*PHI:ih + +# increase the height, and set the width to 3/2 of the height +scale=3/2*oh:3/5*ih + +# increase the size, but make the size a multiple of the chroma +scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub" + +# increase the width to a maximum of 500 pixels, keep the same input aspect ratio +scale='min(500\, iw*3/2):-1' +@end example + @anchor{setdar} @section setdar diff --git a/libavfilter/vf_scale.c b/libavfilter/vf_scale.c index b2b0b636c5..65fe01c9ae 100644 --- a/libavfilter/vf_scale.c +++ b/libavfilter/vf_scale.c @@ -24,9 +24,39 @@ */ #include "avfilter.h" +#include "libavutil/avstring.h" +#include "libavutil/eval.h" #include "libavutil/pixdesc.h" #include "libswscale/swscale.h" +static const char *var_names[] = { + "PI", + "PHI", + "E", + "in_w", "iw", + "in_h", "ih", + "out_w", "ow", + "out_h", "oh", + "a", + "hsub", + "vsub", + 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_HSUB, + VAR_VSUB, + VARS_NB +}; + typedef struct { struct SwsContext *sws; ///< software scaler context @@ -41,6 +71,9 @@ typedef struct { int hsub, vsub; ///< chroma subsampling int slice_y; ///< top of current output slice int input_is_pal; ///< set to 1 if the input format is paletted + + char w_expr[256]; ///< width expression string + char h_expr[256]; ///< height expression string } ScaleContext; static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque) @@ -48,21 +81,16 @@ static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque) ScaleContext *scale = ctx->priv; const char *p; + av_strlcpy(scale->w_expr, "iw", sizeof(scale->w_expr)); + av_strlcpy(scale->h_expr, "ih", sizeof(scale->h_expr)); + scale->flags = SWS_BILINEAR; if (args) { - sscanf(args, "%d:%d", &scale->w, &scale->h); + sscanf(args, "%255[^:]:%255[^:]", scale->w_expr, scale->h_expr); p = strstr(args,"flags="); if (p) scale->flags = strtoul(p+6, NULL, 0); } - /* sanity check params */ - if (scale->w < -1 || scale->h < -1) { - av_log(ctx, AV_LOG_ERROR, "Size values less than -1 are not acceptable.\n"); - return AVERROR(EINVAL); - } - if (scale->w == -1 && scale->h == -1) - scale->w = scale->h = 0; - return 0; } @@ -109,6 +137,48 @@ static int config_props(AVFilterLink *outlink) AVFilterLink *inlink = outlink->src->inputs[0]; ScaleContext *scale = ctx->priv; int64_t w, h; + double var_values[VARS_NB], res; + char *expr; + int ret; + + 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] = (float) inlink->w / inlink->h; + var_values[VAR_HSUB] = 1<<av_pix_fmt_descriptors[inlink->format].log2_chroma_w; + var_values[VAR_VSUB] = 1<<av_pix_fmt_descriptors[inlink->format].log2_chroma_h; + + /* evaluate width and height */ + av_expr_parse_and_eval(&res, (expr = scale->w_expr), + var_names, var_values, + NULL, NULL, NULL, NULL, NULL, 0, ctx); + scale->w = var_values[VAR_OUT_W] = var_values[VAR_OW] = res; + if ((ret = av_expr_parse_and_eval(&res, (expr = scale->h_expr), + var_names, var_values, + NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) + goto fail; + scale->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 = scale->w_expr), + var_names, var_values, + NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) + goto fail; + scale->w = res; + + w = scale->w; + h = scale->h; + + /* sanity check params */ + if (w < -1 || h < -1) { + av_log(ctx, AV_LOG_ERROR, "Size values less than -1 are not acceptable.\n"); + return AVERROR(EINVAL); + } + if (w == -1 && h == -1) + scale->w = scale->h = 0; if (!(w = scale->w)) w = inlink->w; @@ -142,6 +212,11 @@ static int config_props(AVFilterLink *outlink) return AVERROR(EINVAL); return 0; + +fail: + av_log(NULL, AV_LOG_ERROR, + "Error when evaluating the expression '%s'\n", expr); + return ret; } static void start_frame(AVFilterLink *link, AVFilterBufferRef *picref) |