From: Andri Yngvason <andri@yngvason.is>
Date: Thu, 22 Aug 2024 21:26:59 +0000 (+0000)
Subject: H264Libav: Use nearest-neighbour sampling in scaler
X-Git-Url: https://source.dussan.org/?a=commitdiff_plain;h=c68714aee15f1e6c75d53c398ea9b9178f64fcfb;p=tigervnc.git

H264Libav: Use nearest-neighbour sampling in scaler

sws_getCachedContext will set a default sampling method if 0 is passed
to the flags argument. This means that when it is called again, the
flags argument will not match the flags in the context, so a new one
will be allocated every time.

To get around this problem, we assign an explicit sampling method, one
that also happens to be more efficient and just as good for this
use-case as the default one, which is bicubic interpolation.
---

diff --git a/common/rfb/H264LibavDecoderContext.cxx b/common/rfb/H264LibavDecoderContext.cxx
index c3153fd1..73bfb68c 100644
--- a/common/rfb/H264LibavDecoderContext.cxx
+++ b/common/rfb/H264LibavDecoderContext.cxx
@@ -215,7 +215,7 @@ void H264LibavDecoderContext::decode(const uint8_t* h264_in_buffer,
 
   sws = sws_getCachedContext(sws, frame->width, frame->height, avctx->pix_fmt,
                              frame->width, frame->height, AV_PIX_FMT_RGB32,
-                             0, nullptr, nullptr, nullptr);
+                             SWS_POINT, nullptr, nullptr, nullptr);
 
   int inFull, outFull, brightness, contrast, saturation;
   const int* inTable;