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From: Anton Khirnov <anton@khirnov.net>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Cc: Leo Izen <leo.izen@gmail.com>
Subject: Re: [FFmpeg-devel] [PATCH] avcodec/pnm: avoid mirroring PFM images vertically
Date: Tue, 29 Nov 2022 12:14:00 +0100
Message-ID: <166972044003.4503.6154057733583441158@lain.khirnov.net> (raw)
In-Reply-To: <20221116114306.251999-1-leo.izen@gmail.com>

Quoting Leo Izen (2022-11-16 12:43:06)
> PFM (aka Portable FloatMap) encodes its scanlines from bottom-to-top,
> not from top-to-bottom, unlike other NetPBM formats. Without this
> patch, FFmpeg ignores this exception and decodes/encodes PFM images
> mirrored vertically from their proper orientation.
> 
> For reference, see the NetPBM tool pfmtopam, which encodes a .pam
> from a .pfm, using the correct orientation (and which FFmpeg reads
> correctly). Also compare ffplay to magick display, which shows the
> correct orientation as well.
> 
> See: http://www.pauldebevec.com/Research/HDR/PFM/ and see:
> https://netpbm.sourceforge.net/doc/pfm.html for descriptions of this
> image format.
> 
> Signed-off-by: Leo Izen <leo.izen@gmail.com>
> ---
>  libavcodec/pnmdec.c          | 10 ++++++++++
>  libavcodec/pnmenc.c          | 18 ++++++++++--------
>  tests/ref/lavf/gbrpf32be.pfm |  2 +-
>  tests/ref/lavf/gbrpf32le.pfm |  2 +-
>  tests/ref/lavf/grayf32be.pfm |  2 +-
>  tests/ref/lavf/grayf32le.pfm |  2 +-
>  6 files changed, 24 insertions(+), 12 deletions(-)

Looks reasonable, will push soonish.

-- 
Anton Khirnov
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  parent reply	other threads:[~2022-11-29 11:14 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-16 11:43 Leo Izen
2022-11-22 16:46 ` Leo Izen
2022-11-28  9:11   ` Leo Izen
2022-11-29 11:14 ` Anton Khirnov [this message]
2022-12-14 20:13   ` Leo Izen
2022-12-27 13:38     ` Leo Izen
2022-12-27 13:42       ` James Almer

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