vf_scale.c
/*
* Copyright (c) 2007 Bobby Bingham
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* scale video filter
*/
#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
/**
* New dimensions. Special values are:
* 0 = original width/height
* -1 = keep original aspect
*/
int w, h;
unsigned int flags; ///sws flags
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)
{
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, "%255[^:]:%255[^:]", scale->w_expr, scale->h_expr);
p = strstr(args,"flags=");
if (p) scale->flags = strtoul(p+6, NULL, 0);
}
return 0;
}
static av_cold void uninit(AVFilterContext *ctx)
{
ScaleContext *scale = ctx->priv;
sws_freeContext(scale->sws);
scale->sws = NULL;
}
static int query_formats(AVFilterContext *ctx)
{
AVFilterFormats *formats;
enum PixelFormat pix_fmt;
int ret;
if (ctx->inputs[0]) {
formats = NULL;
for (pix_fmt = 0; pix_fmt < PIX_FMT_NB; pix_fmt++)
if ( sws_isSupportedInput(pix_fmt)
&& (ret = avfilter_add_format(&formats, pix_fmt)) < 0) {
avfilter_formats_unref(&formats);
return ret;
}
avfilter_formats_ref(formats, &ctx->inputs[0]->out_formats);
}
if (ctx->outputs[0]) {
formats = NULL;
for (pix_fmt = 0; pix_fmt < PIX_FMT_NB; pix_fmt++)
if ( sws_isSupportedOutput(pix_fmt)
&& (ret = avfilter_add_format(&formats, pix_fmt)) < 0) {
avfilter_formats_unref(&formats);
return ret;
}
avfilter_formats_ref(formats, &ctx->outputs[0]->in_formats);
}
return 0;
}
static int config_props(AVFilterLink *outlink)
{
AVFilterContext *ctx = outlink->src;
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;
if (!(h = scale->h))
h = inlink->h;
if (w == -1)
w = av_rescale(h, inlink->w, inlink->h);
if (h == -1)
h = av_rescale(w, inlink->h, inlink->w);
if (w > INT_MAX || h > INT_MAX ||
(h * inlink->w) > INT_MAX ||
(w * inlink->h) > INT_MAX)
av_log(ctx, AV_LOG_ERROR, "Rescaled value for width or height is too big.\n");
outlink->w = w;
outlink->h = h;
/* TODO: make algorithm configurable */
av_log(ctx, AV_LOG_INFO, "w:%d h:%d fmt:%s -> w:%d h:%d fmt:%s flags:0x%0x\n",
inlink ->w, inlink ->h, av_pix_fmt_descriptors[ inlink->format].name,
outlink->w, outlink->h, av_pix_fmt_descriptors[outlink->format].name,
scale->flags);
scale->input_is_pal = av_pix_fmt_descriptors[inlink->format].flags & PIX_FMT_PAL;
if (scale->sws)
sws_freeContext(scale->sws);
scale->sws = sws_getContext(inlink ->w, inlink ->h, inlink ->format,
outlink->w, outlink->h, outlink->format,
scale->flags, NULL, NULL, NULL);
if (!scale->sws)
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)
{
ScaleContext *scale = link->dst->priv;
AVFilterLink *outlink = link->dst->outputs[0];
AVFilterBufferRef *outpicref;
scale->hsub = av_pix_fmt_descriptors[link->format].log2_chroma_w;
scale->vsub = av_pix_fmt_descriptors[link->format].log2_chroma_h;
outpicref = avfilter_get_video_buffer(outlink, AV_PERM_WRITE, outlink->w, outlink->h);
avfilter_copy_buffer_ref_props(outpicref, picref);
outpicref->video->w = outlink->w;
outpicref->video->h = outlink->h;
outlink->out_buf = outpicref;
av_reduce(&outpicref->video->pixel_aspect.num, &outpicref->video->pixel_aspect.den,
(int64_t)picref->video->pixel_aspect.num * outlink->h * link->w,
(int64_t)picref->video->pixel_aspect.den * outlink->w * link->h,
INT_MAX);
scale->slice_y = 0;
avfilter_start_frame(outlink, avfilter_ref_buffer(outpicref, ~0));
}
static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
{
ScaleContext *scale = link->dst->priv;
int out_h;
AVFilterBufferRef *cur_pic = link->cur_buf;
const uint8_t *data[4];
if (scale->slice_y == 0 && slice_dir == -1)
scale->slice_y = link->dst->outputs[0]->h;
data[0] = cur_pic->data[0] + y * cur_pic->linesize[0];
data[1] = scale->input_is_pal ?
cur_pic->data[1] :
cur_pic->data[1] + (y>>scale->vsub) * cur_pic->linesize[1];
data[2] = cur_pic->data[2] + (y>>scale->vsub) * cur_pic->linesize[2];
data[3] = cur_pic->data[3] + y * cur_pic->linesize[3];
out_h = sws_scale(scale->sws, data, cur_pic->linesize, y, h,
link->dst->outputs[0]->out_buf->data,
link->dst->outputs[0]->out_buf->linesize);
if (slice_dir == -1)
scale->slice_y -= out_h;
avfilter_draw_slice(link->dst->outputs[0], scale->slice_y, out_h, slice_dir);
if (slice_dir == 1)
scale->slice_y += out_h;
}
AVFilter avfilter_vf_scale = {
.name = "scale",
.description = NULL_IF_CONFIG_SMALL("Scale the input video to width:height size and/or convert the image format."),
.init = init,
.uninit = uninit,
.query_formats = query_formats,
.priv_size = sizeof(ScaleContext),
.inputs = (AVFilterPad[]) {{ .name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.start_frame = start_frame,
.draw_slice = draw_slice,
.min_perms = AV_PERM_READ, },
{ .name = NULL}},
.outputs = (AVFilterPad[]) {{ .name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.config_props = config_props, },
{ .name = NULL}},
};
