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* [FFmpeg-devel] [PATCH 1/7] lavu/pixfmt: summarize yuv naming conventions
@ 2022-08-02 16:54 Nicolas George
  2022-08-02 16:54 ` [FFmpeg-devel] [PATCH 2/7] lavfi/graphdump: add plain listing output Nicolas George
                   ` (6 more replies)
  0 siblings, 7 replies; 12+ messages in thread
From: Nicolas George @ 2022-08-02 16:54 UTC (permalink / raw)
  To: ffmpeg-devel

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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^ permalink raw reply	[flat|nested] 12+ messages in thread

end of thread, other threads:[~2022-08-06 10:36 UTC | newest]

Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-08-02 16:54 [FFmpeg-devel] [PATCH 1/7] lavu/pixfmt: summarize yuv naming conventions Nicolas George
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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