From c673ef12885fdc007b21b9f52cdd50211d452d97 Mon Sep 17 00:00:00 2001
From: Carl Eugen Hoyos <cehoyos@ag.or.at>
Date: Mon, 5 Nov 2012 04:43:17 +0100
Subject: [PATCH] Write tiff tag YCbCrPositioning if chroma_sample_location is
 top-left.

---
 libavcodec/tiffenc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavcodec/tiffenc.c b/libavcodec/tiffenc.c
index dae9147e4e..d4402859f0 100644
--- a/libavcodec/tiffenc.c
+++ b/libavcodec/tiffenc.c
@@ -471,6 +471,8 @@ static int encode_frame(AVCodecContext * avctx, AVPacket *pkt,
         /** according to CCIR Recommendation 601.1 */
         uint32_t refbw[12] = {15, 1, 235, 1, 128, 1, 240, 1, 128, 1, 240, 1};
         add_entry(s, TIFF_YCBCR_SUBSAMPLING, TIFF_SHORT,    2, s->subsampling);
+        if (avctx->chroma_sample_location == AVCHROMA_LOC_TOPLEFT)
+            add_entry1(s, TIFF_YCBCR_POSITIONING, TIFF_SHORT, 2);
         add_entry(s, TIFF_REFERENCE_BW,      TIFF_RATIONAL, 6, refbw);
     }
     bytestream_put_le32(&offset, ptr - pkt->data);    // write offset to dir