[Ffmpeg-cvslog] CVS: ffmpeg/doc optimization.txt,1.8,1.9
Diego Biurrun CVS
diego
Sat Jun 11 19:32:24 CEST 2005
Update of /cvsroot/ffmpeg/ffmpeg/doc
In directory mail:/var2/tmp/cvs-serv23532
Modified Files:
optimization.txt
Log Message:
Cosmetics: Removed trailing whitespace, converted tabs to spaces.
Index: optimization.txt
===================================================================
RCS file: /cvsroot/ffmpeg/ffmpeg/doc/optimization.txt,v
retrieving revision 1.8
retrieving revision 1.9
diff -u -d -r1.8 -r1.9
--- optimization.txt 11 Apr 2005 16:24:58 -0000 1.8
+++ optimization.txt 11 Jun 2005 17:32:22 -0000 1.9
@@ -10,12 +10,12 @@
arent many left
Understanding these overoptimized functions:
-as many functions, like the c ones tend to be a bit unreadable currently becouse
-of optimizations it is difficult to understand them (and write arichtecture
+as many functions, like the c ones tend to be a bit unreadable currently becouse
+of optimizations it is difficult to understand them (and write arichtecture
specific versions, or optimize the c functions further) it is recommanded to look
-at older CVS versions of the interresting files (just use CVSWEB at
+at older CVS versions of the interresting files (just use CVSWEB at
http://www1.mplayerhq.hu/cgi-bin/cvsweb.cgi/ffmpeg/libavcodec/?cvsroot=FFmpeg)
-or perhaps look into the other architecture specific versions in i386/, ppc/,
+or perhaps look into the other architecture specific versions in i386/, ppc/,
alpha/, ...; even if u dont understand the instructions exactly it could help
understanding the functions & how they can be optimized
@@ -29,106 +29,106 @@
which are rarely used
put(_no_rnd)_pixels{,_x2,_y2,_xy2}
- used in motion compensation (en/decoding)
+ used in motion compensation (en/decoding)
avg_pixels{,_x2,_y2,_xy2}
- used in motion compensation of B Frames
- these are less important then the put*pixels functions
+ used in motion compensation of B Frames
+ these are less important then the put*pixels functions
avg_no_rnd_pixels*
- unused
+ unused
pix_abs16x16{,_x2,_y2,_xy2}
- used in motion estimation (encoding) with SAD
+ used in motion estimation (encoding) with SAD
pix_abs8x8{,_x2,_y2,_xy2}
- used in motion estimation (encoding) with SAD of MPEG4 4MV only
- these are less important then the pix_abs16x16* functions
+ used in motion estimation (encoding) with SAD of MPEG4 4MV only
+ these are less important then the pix_abs16x16* functions
put_mspel8_mc* / wmv2_mspel8*
- used only in WMV2
- it is not recommanded that u waste ur time with these, as WMV2 is a
- ugly and relativly useless codec
+ used only in WMV2
+ it is not recommanded that u waste ur time with these, as WMV2 is a
+ ugly and relativly useless codec
mpeg4_qpel* / *qpel_mc*
- use in MPEG4 qpel Motion compensation (encoding & decoding)
- the qpel8 functions are used only for 4mv
- the avg_* functions are used only for b frames
- optimizing them should have a significant impact on qpel encoding & decoding
-
+ use in MPEG4 qpel Motion compensation (encoding & decoding)
+ the qpel8 functions are used only for 4mv
+ the avg_* functions are used only for b frames
+ optimizing them should have a significant impact on qpel encoding & decoding
+
qpel{8,16}_mc??_old_c / *pixels{8,16}_l4
- just used to workaround a bug in old libavcodec encoder
- dont optimze them
+ just used to workaround a bug in old libavcodec encoder
+ dont optimze them
tpel_mc_func {put,avg}_tpel_pixels_tab
- used only for SVQ3, so only optimze them if u need fast SVQ3 decoding
+ used only for SVQ3, so only optimze them if u need fast SVQ3 decoding
add_bytes/diff_bytes
- for huffyuv only, optimize if u want a faster ff-huffyuv codec
+ for huffyuv only, optimize if u want a faster ff-huffyuv codec
get_pixels / diff_pixels
- used for encoding, easy
-
+ used for encoding, easy
+
clear_blocks
- easiest, to optimize
-
+ easiest, to optimize
+
gmc
- used for mpeg4 gmc
- optimizing this should have a significant effect on the gmc decoding speed but
- its very likely impossible to write in SIMD
+ used for mpeg4 gmc
+ optimizing this should have a significant effect on the gmc decoding speed but
+ its very likely impossible to write in SIMD
gmc1
- used for chroma blocks in mpeg4 gmc with 1 warp point
- (there are 4 luma & 2 chroma blocks per macrobock, so
- only 1/3 of the gmc blocks use this, the other 2/3
- use the normal put_pixel* code, but only if there is
- just 1 warp point)
- Note: Divx5 gmc always uses just 1 warp point
+ used for chroma blocks in mpeg4 gmc with 1 warp point
+ (there are 4 luma & 2 chroma blocks per macrobock, so
+ only 1/3 of the gmc blocks use this, the other 2/3
+ use the normal put_pixel* code, but only if there is
+ just 1 warp point)
+ Note: Divx5 gmc always uses just 1 warp point
pix_sum
- used for encoding
-
+ used for encoding
+
hadamard8_diff / sse / sad == pix_norm1 / dct_sad / quant_psnr / rd / bit
- specific compare functions used in encoding, it depends upon the command line
- switches which of these are used
- dont waste ur time with dct_sad & quant_psnr they arent really usefull
+ specific compare functions used in encoding, it depends upon the command line
+ switches which of these are used
+ dont waste ur time with dct_sad & quant_psnr they arent really usefull
put_pixels_clamped / add_pixels_clamped
- used for en/decoding in the IDCT, easy
- Note, some optimized IDCTs have the add/put clamped code included and then
- put_pixels_clamped / add_pixels_clamped will be unused
+ used for en/decoding in the IDCT, easy
+ Note, some optimized IDCTs have the add/put clamped code included and then
+ put_pixels_clamped / add_pixels_clamped will be unused
idct/fdct
- idct (encoding & decoding)
- fdct (encoding)
- difficult to optimize
-
+ idct (encoding & decoding)
+ fdct (encoding)
+ difficult to optimize
+
dct_quantize_trellis
- used for encoding with trellis quantization
- difficult to optimize
+ used for encoding with trellis quantization
+ difficult to optimize
dct_quantize
- used for encoding
-
+ used for encoding
+
dct_unquantize_mpeg1
- used in mpeg1 en/decoding
+ used in mpeg1 en/decoding
dct_unquantize_mpeg2
- used in mpeg2 en/decoding
+ used in mpeg2 en/decoding
dct_unquantize_h263
- used in mpeg4/h263 en/decoding
+ used in mpeg4/h263 en/decoding
FIXME remaining functions?
btw, most of these are in dsputil.c/.h some are in mpegvideo.c/.h
-
+
Alignment:
some instructions on some architectures have strict alignment restrictions,
for example most SSE/SSE2 inctructios on X86
the minimum guranteed alignment is writen in the .h files
-for example:
+for example:
void (*put_pixels_clamped)(const DCTELEM *block/*align 16*/, UINT8 *pixels/*align 8*/, int line_size);
@@ -139,7 +139,7 @@
X86 specific:
http://developer.intel.com/design/pentium4/manuals/248966.htm
-The IA-32 Intel Architecture Software Developer's Manual, Volume 2:
+The IA-32 Intel Architecture Software Developer's Manual, Volume 2:
Instruction Set Reference
http://developer.intel.com/design/pentium4/manuals/245471.htm
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