diff --git a/doc/optimization.txt b/doc/optimization.txt index 08caa89c1b..f435d0f0cb 100644 --- a/doc/optimization.txt +++ b/doc/optimization.txt @@ -10,12 +10,12 @@ i386 directory or find some other functions in the c source to optimize, but the 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 @@ the primary purpose of that list is to avoid wasting time to optimize functions 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 @@ http://www.aggregate.org/MAGIC/ 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