[FBcode->GH] torchvision decoder. fix artifacts, blury images for frame...

[FBcode->GH] torchvision decoder. fix artifacts, blury images for frame dimensions not multiple of 8 (#7523) (#7552)
Co-authored-by: Vadim Zubov <vadikrobot@meta.com>

torchvision/csrc/io/decoder/video_sampler.cpp

@@ -181,6 +181,23 @@ bool VideoSampler::init(const SamplerParameters& params) {
   // set output format
   params_ = params;
 
+  if (params.in.video.format == AV_PIX_FMT_YUV420P) {
+    /* When the video width and height are not multiples of 8,
+     * and there is no size change in the conversion,
+     * a blurry screen will appear on the right side
+     * This problem was discovered in 2012 and
+     * continues to exist in version 4.1.3 in 2019
+     * This problem can be avoided by increasing SWS_ACCURATE_RND
+     * details https://trac.ffmpeg.org/ticket/1582
+     */
+    if ((params.in.video.width & 0x7) || (params.in.video.height & 0x7)) {
+      VLOG(1) << "The width " << params.in.video.width << " and height "
+              << params.in.video.height << " the image is not a multiple of 8, "
+              << "the decoding speed may be reduced";
+      swsFlags_ |= SWS_ACCURATE_RND;
+    }
+  }
+
   scaleContext_ = sws_getContext(
       params.in.video.width,
       params.in.video.height,