On Sat, 12 Aug 2017, Dave Rice wrote:
[..]
Also utils.c associates these field order values with the following labels:
AV_FIELD_TB -> "top coded first (swapped)";
AV_FIELD_BT -> "bottom coded first (swapped)";
From my reading, I infer that "top coded first (swapped)” means "top
coded first, bottom displayed first”; however in practice from files
generated by QuickTime and FFmpeg files with a value of TB have the top
field displayed first, so I think the labels are swapped. In the patch
below I suggest using “top first (interleaved)” for TB and “bottom first
(interleaved)” for BT.
Comments?
From de871b3fa891fa0ae6856461c1f8305cc889cde7 Mon Sep 17 00:00:00 2001
From: Dave Rice <d...@dericed.com>
Date: Sat, 12 Aug 2017 12:30:43 -0400
Subject: [PATCH] libavcodec: fix field_order labelling
---
libavcodec/avcodec.h | 4 ++--
libavcodec/utils.c | 4 ++--
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index c594993766..37c39072b3 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -1726,8 +1726,8 @@ enum AVFieldOrder {
AV_FIELD_PROGRESSIVE,
AV_FIELD_TT, //< Top coded_first, top displayed first
AV_FIELD_BB, //< Bottom coded first, bottom displayed first
- AV_FIELD_TB, //< Top coded first, bottom displayed first
- AV_FIELD_BT, //< Bottom coded first, top displayed first
+ AV_FIELD_TB, //< Interleaved coding, top displayed first
+ AV_FIELD_BT, //< Interleaved coding, bottom displayed first
};
I agree that a lot of stuff in the codebase is consistent with the updated
descriptions. However, as far as I see libavformat/mxfdec.c seems to
follow the existing docs, so I think that needs changing as well.
Regards,
Marton
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