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authorVittorio Giovara <vittorio.giovara@gmail.com>2013-10-01 19:11:00 +0200
committerLuca Barbato <lu_zero@gentoo.org>2013-10-05 18:38:55 +0200
commit6b3ff6f91a535d6383f41ca7bdf760165dcb6015 (patch)
treeb25f7e164c6b4ec96e8648eac066cb13aac23a6d /libswscale
parent258414d0771845d20f646ffe4d4e60f22fba217c (diff)
downloadffmpeg-6b3ff6f91a535d6383f41ca7bdf760165dcb6015.tar.gz
swscale: provide a default scaler if none is set
Lanczos for general case, sinc for upscaling, Gaussian for downscaling. According to current literature these scalers should be the best quality-wise algorithms for each case. Inspired from a patch by wm4 <nfxjfg@googlemail.com> Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
Diffstat (limited to 'libswscale')
-rw-r--r--libswscale/utils.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/libswscale/utils.c b/libswscale/utils.c
index 27819854e4..2111fc2a62 100644
--- a/libswscale/utils.c
+++ b/libswscale/utils.c
@@ -914,7 +914,17 @@ av_cold int sws_init_context(SwsContext *c, SwsFilter *srcFilter,
SWS_SINC |
SWS_SPLINE |
SWS_BICUBLIN);
- if (!i || (i & (i - 1))) {
+
+ /* provide a default scaler if not set by caller */
+ if (!i) {
+ if (dstW < srcW && dstH < srcH)
+ flags |= SWS_GAUSS;
+ else if (dstW > srcW && dstH > srcH)
+ flags |= SWS_SINC;
+ else
+ flags |= SWS_LANCZOS;
+ c->flags = flags;
+ } else if (i & (i - 1)) {
av_log(c, AV_LOG_ERROR,
"Exactly one scaler algorithm must be chosen\n");
return AVERROR(EINVAL);