[FFmpeg-trac] #9526(avutil:closed): AV_PIX_FMT_YUV410P description incorrect
FFmpeg
trac at avcodec.org
Thu Nov 25 01:16:28 EET 2021
#9526: AV_PIX_FMT_YUV410P description incorrect
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Reporter: Anton1699 | Owner: (none)
Type: defect | Status: closed
Priority: normal | Component: avutil
Version: git-master | Resolution: invalid
Keywords: pixdesc | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Changes (by Marton Balint):
* status: new => closed
* resolution: => invalid
Comment:
4:1:0 notation can be used for both one chroma pair per 4x2 block and one
chroma pair per 4x4 block. However in ffmpeg AV_PIX_FMT_YUV410P means the
latter, one chroma pair per 4x4 block.
Even wikipedia is confused and using both terms:
https://en.wikipedia.org/wiki/Chroma_subsampling
''This notation is not valid for all combinations and has exceptions, e.g.
4:1:0 (where the height of the region is not 2 pixels, but 4 pixels, so if
8 bits per component are used, the media would be 9 bits per pixel) and
4:2:1.''
but later:
''This ratio uses half of the vertical and one-fourth the horizontal color
resolutions, with only one-eighth of the bandwidth of the maximum color
resolutions used. Uncompressed video in this format with 8-bit
quantization uses 10 bytes for every macropixel (which is 4×2 pixels).
Some video codecs may operate at 4:1:0.5 or 4:1:0.25 as an option, so as
to allow similar to VHS quality.''
So log2_chroma_h is fine as is in ffmpeg.
--
Ticket URL: <https://trac.ffmpeg.org/ticket/9526#comment:2>
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