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vf_scale: add force_original_aspect_ratio

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Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Timothy Gu 2013-08-03 16:30:00 -07:00 committed by Michael Niedermayer
parent 48188a5120
commit 3415058541
2 changed files with 46 additions and 0 deletions
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27
doc/filters.texi
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@ -6373,6 +6373,33 @@ Full range (0-255 in case of 8bit luma)
"Mpeg" range (16-235 in case of 8bit luma)
@end table
@item force_original_aspect_ratio
Enable decreasing or increasing output video width or height if necessary to
keep the original aspect ratio. Possible values:
@table @samp
@item disable
Scale the video as specified and disable this feature.
@item decrease
The output video dimensions will automatically be decreased if needed.
@item increase
The output video dimensions will automatically be increased if needed.
@end table
One useful instance of this option is that when you know a specific device's
maximum allowed resolution, you can use this to limit the output video to
that, while retaining the aspect ratio. For example, device A allows
1280x720 playback, and your video is 1920x800. Using this option (set it to
decrease) and specifying 1280x720 to the command line makes the output
1280x533.
Please note that this is a different thing than specifying -1 for @option{w}
or @option{h}, you still need to specify the output resolution for this option
to work.
@end table
The values of the @var{w} and @var{h} options are expressions

19
libavfilter/vf_scale.c
View File

@ -101,6 +101,8 @@ typedef struct {
int out_v_chr_pos;
int in_h_chr_pos;
int in_v_chr_pos;
int force_original_aspect_ratio;
} ScaleContext;
static av_cold int init(AVFilterContext *ctx)
@ -274,6 +276,19 @@ static int config_props(AVFilterLink *outlink)
if (h == -1)
h = av_rescale(w, inlink->h, inlink->w);
if (scale->force_original_aspect_ratio) {
int tmp_w = av_rescale(h, inlink->w, inlink->h);
int tmp_h = av_rescale(w, inlink->h, inlink->w);
if (scale->force_original_aspect_ratio == 1) {
w = FFMIN(tmp_w, w);
h = FFMIN(tmp_h, h);
} else {
w = FFMAX(tmp_w, w);
h = FFMAX(tmp_h, h);
}
}
if (w > INT_MAX || h > INT_MAX ||
(h * inlink->w) > INT_MAX ||
(w * inlink->h) > INT_MAX)
@ -501,6 +516,10 @@ static const AVOption scale_options[] = {
{ "in_h_chr_pos", "input horizontal chroma position in luma grid/256", OFFSET(in_h_chr_pos), AV_OPT_TYPE_INT, { .i64 = -1}, -1, 512, FLAGS },
{ "out_v_chr_pos", "output vertical chroma position in luma grid/256" , OFFSET(out_v_chr_pos), AV_OPT_TYPE_INT, { .i64 = -1}, -1, 512, FLAGS },
{ "out_h_chr_pos", "output horizontal chroma position in luma grid/256", OFFSET(out_h_chr_pos), AV_OPT_TYPE_INT, { .i64 = -1}, -1, 512, FLAGS },
{ "force_original_aspect_ratio", "decrease or increase w/h if necessary to keep the original AR", OFFSET(force_original_aspect_ratio), AV_OPT_TYPE_INT, { .i64 = 0}, 0, 2, FLAGS, "force_oar" },
{ "disable", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = 0 }, 0, 0, FLAGS, "force_oar" },
{ "decrease", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = 1 }, 0, 0, FLAGS, "force_oar" },
{ "increase", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = 2 }, 0, 0, FLAGS, "force_oar" },
{ NULL },
};