From: Nicolas George <george@nsup.org>
To: ffmpeg-devel@ffmpeg.org
Subject: [FFmpeg-devel] [PATCH 1/7] lavu/pixfmt: summarize yuv naming conventions
Date: Tue, 2 Aug 2022 18:54:15 +0200
Message-ID: <20220802165421.137563-1-george@nsup.org> (raw)
Signed-off-by: Nicolas George <george@nsup.org>
---
libavutil/pixfmt.h | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
Identical to the one I posted last week.
diff --git a/libavutil/pixfmt.h b/libavutil/pixfmt.h
index 2d3927cc3f..3d0f92ed4d 100644
--- a/libavutil/pixfmt.h
+++ b/libavutil/pixfmt.h
@@ -60,6 +60,23 @@
* For all the 8 bits per pixel formats, an RGB32 palette is in data[1] like
* for pal8. This palette is filled in automatically by the function
* allocating the picture.
+ *
+ * @par
+ * Summary of the naming conventions for YUV formats:
+ * 444 422 440 420 411 410
+ * ╋━╋━╋━╋━╋ ╋━┿━╋━┿━╋ ╋━╋━╋━╋━╋ ╋━┿━╋━┿━╋ ╋━┿━┿━┿━╋ ╋━┿━┿━┿━╋
+ * ╋━╋━╋━╋━╋ ╋━┿━╋━┿━╋ ╂─╂─╂─╂─╂ ╂─┼─╂─┼─╂ ╋━┿━┿━┿━╋ ╂─┼─┼─┼─╂
+ * ╋━╋━╋━╋━╋ ╋━┿━╋━┿━╋ ╋━╋━╋━╋━╋ ╋━┿━╋━┿━╋ ╋━┿━┿━┿━╋ ╂─┼─┼─┼─╂
+ * ╋━╋━╋━╋━╋ ╋━┿━╋━┿━╋ ╂─╂─╂─╂─╂ ╂─┼─╂─┼─╂ ╋━┿━┿━┿━╋ ╂─┼─┼─┼─╂
+ * ╋━╋━╋━╋━╋ ╋━┿━╋━┿━╋ ╋━╋━╋━╋━╋ ╋━┿━╋━┿━╋ ╋━┿━┿━┿━╋ ╋━┿━┿━┿━╋
+ * where
+ * ┼─┼ = luma pixel ╋━╋ = chroma pixel
+ * ┼─┼ ╋━╋
+ *
+ * yuv4ab →
+ * log2_chroma_w = log₂(4/a)
+ * log2_chroma_h = b == a ? 0 : b == 0 ? log2_chroma_w : unused
+ * i.e. a = horizontally, number of luma pixels for four chroma pixels
*/
enum AVPixelFormat {
AV_PIX_FMT_NONE = -1,
--
2.35.1
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next reply other threads:[~2022-08-02 16:54 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-02 16:54 Nicolas George [this message]
2022-08-02 16:54 ` [FFmpeg-devel] [PATCH 2/7] lavfi/graphdump: add plain listing output Nicolas George
2022-08-02 16:54 ` [FFmpeg-devel] [PATCH 3/7] fftools: add -lavfi_dump option Nicolas George
2022-08-02 16:54 ` [FFmpeg-devel] [PATCH 4/7] lavfi/(a)format: factor finding the delimiter Nicolas George
2022-08-02 16:54 ` [FFmpeg-devel] [PATCH 5/7] lavfi/(a)format: support slash as a delimiter Nicolas George
2022-08-02 16:54 ` [FFmpeg-devel] [PATCH 6/7] lavi/pixdesc: add comments about pixel format scoring Nicolas George
2022-08-04 13:52 ` Michael Niedermayer
2022-08-02 16:54 ` [FFmpeg-devel] [PATCH 7/7] tests: add coverage for libavfilter's format negotiation Nicolas George
2022-08-04 13:49 ` [FFmpeg-devel] [PATCH 1/7] lavu/pixfmt: summarize yuv naming conventions Michael Niedermayer
2022-08-04 13:57 ` Nicolas George
2022-08-04 15:04 ` Michael Niedermayer
2022-08-06 10:36 ` Nicolas George
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