H264Libav: Handle colour space conversion

The scaler is now informed of the colour space encoded into the stream
so that it may do the proper conversion.

(cherry picked from commit 28cc17e)

common/rfb/H264LibavDecoderContext.cxx

@@ -217,6 +217,21 @@ void H264LibavDecoderContext::decode(const uint8_t* h264_in_buffer,
                              frame->width, frame->height, AV_PIX_FMT_RGB32,
                              0, NULL, NULL, NULL);
 
+  int inFull, outFull, brightness, contrast, saturation;
+  const int* inTable;
+  const int* outTable;
+
+  sws_getColorspaceDetails(sws, (int**)&inTable, &inFull, (int**)&outTable,
+      &outFull, &brightness, &contrast, &saturation);
+  if (frame->colorspace != AVCOL_SPC_UNSPECIFIED) {
+    inTable = sws_getCoefficients(frame->colorspace);
+  }
+  if (frame->color_range != AVCOL_RANGE_UNSPECIFIED) {
+    inFull = frame->color_range == AVCOL_RANGE_JPEG;
+  }
+  sws_setColorspaceDetails(sws, inTable, inFull, outTable, outFull, brightness,
+      contrast, saturation);
+
   if (rgbFrame && (rgbFrame->width != frame->width || rgbFrame->height != frame->height)) {
     av_frame_free(&rgbFrame);