[FFmpeg-devel] [PATCH] FFV1 specification: Reduce redundancy in the description of xxPlane() and xxLine()

Michael Niedermayer michaelni at gmx.at
Sun May 3 18:40:12 CEST 2015


On Sun, May 03, 2015 at 02:59:59PM +0200, Jerome Martinez wrote:
> Le 03/05/2015 13:55, Michael Niedermayer a écrit :
> >On Sun, May 03, 2015 at 12:31:05PM +0200, Jerome Martinez wrote:
> >>- plane_count which is the count of planes
> >thats a bad name for packed formats
> 
> Good point, but this is not worse than the previous name used ;-).
> and actually you use "alpha_plane" even for color_space = 1 (so no planes)
> 
> Attached is a new patch with channel_count name.
> "channel" wording taken from
> https://www.ffmpeg.org/ffmpeg-all.html#extractplanes .
> should I also change, in another patch, chroma_planes and
> alpha_plane to chroma_channels and alpha_channel for more coherency?
> 
> >
> >
> >>- quant_table_index_count which is the count of quant_table indexes
> >any reason not to call it quant_table_count ? (its shorter and seems
> >not to contain less information)
> 
> quant_table_count is already defined as the count of quantization
> tables (in the header), we can not reuse that name for something
> different.
> here, it is the count of quantization table indexes, which is
> different (it is possible to have 1000 quantization tables, but we
> can have only up to 3 quantization indexes in the slice) if I well
> understood.
> I would like to have something shorter too, but I preferred not to
> modify quant_table_index[i][j]
> 
> quant_table_count is the count of quant_tables
> quant_table_index_count is the count of quant_table_index.

> 
[...]

>  ffv1.lyx |  801 ++++-----------------------------------------------------------
>  1 file changed, 53 insertions(+), 748 deletions(-)
> affdeba58b36c8bae4d42b4789768e6c12e2c29b  0001-Reduce-redundancy-in-xxPlane-and-xxLine.patch
> From 9f4b73e4153b6c4829d814da15bf22695f1e3df9 Mon Sep 17 00:00:00 2001
> From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Martinez?= <jerome at mediaarea.net>
> Date: Sun, 3 May 2015 14:57:27 +0200
> Subject: [PATCH] Reduce redundancy in xxPlane() and xxLine().
> 
> LumaPlane(), CbPlane(), CrPlane() and AlphaPlane() are actually same;
> the order of planes is already defined in the General section and has
> no impact on the bitstream. Reduced to one Plane( p ) call.
> LumaLine(), CbLine(), CrLine() and AlphaLine() are actually same;
> the order of lines is already defined in the General section and has
> no impact on the bitstream. Reduced to one Line( p, y ) call.
> plane_count name may be misleading (it is the count of
> quant_table_index, which is not always the count of planes) and
> does not exist in the bistream, replaced by the sum of existing
> bitstream elements.
> colorspace_type related "if" sorted in ascending order.

applied

i think
1 + ( chroma_planes ? 2 : 0 ) + ( alpha_plane + ? 1 : 0 )
should be simplified to
1 + 2*chroma_planes + alpha_plane

thanks

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Dictatorship naturally arises out of democracy, and the most aggravated
form of tyranny and slavery out of the most extreme liberty. -- Plato
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