[FFmpeg-soc] [soc]: r3046 - in aac: aac.c aac.h
Michael Niedermayer
michaelni at gmx.at
Thu Aug 7 12:53:50 CEST 2008
On Thu, Aug 07, 2008 at 12:40:28PM +0200, Michael Niedermayer wrote:
> Hi
>
> On Thu, Aug 07, 2008 at 08:50:05AM +0200, Reimar Doeffinger wrote:
> > On Wed, Aug 06, 2008 at 09:21:32PM -0400, Justin Ruggles wrote:
> > > superdump wrote:
> > > > Author: superdump
> > > > Date: Wed Aug 6 12:00:44 2008
> > > > New Revision: 3046
> > > >
> > > > Log:
> > > > Use a simple LCG as recommended in libavutil/lfg.* rather than Mersenne Twister
> > > > as such noise is good enough (sounds the same to my ears on a 1 second sample)
> > > > and calculation is faster
> > >
> > > Why not add that to libavutil as well? I would like to use it for AC-3.
> >
> > In that case though I think it would be nice if there was some additional information
> > on the particular numbers used, and also mentioning that the last bit is always alternating
> > for this kind of generator (so if possible, only the upper bits should be used).
> > Believing some random guy on the internet: http://random.mat.sbg.ac.at/~charly/server/node3.html
> > 2147001325*a+715136305
> > at least has some statistics, I could not find any for the current numbers on a quick search.
>
> heres a quick comparission between the 2 generators:
heres the same, also with the next (poorly performing generator) from the
url as check if my tests catch poorly performing ones
*1664525+1013904223 *2147001325+715136305 (*452807053) & 0x7FFFFFFF;
test:0 tp: 0 0-16777208 0-16777208 0-67108830
test:0 tp: 1 0-4194304 0-4194304 0-16777216
test:0 tp: 2 0-1048576 0-1048576 0-4194304
test:0 tp: 3 0-262144 0-262144 0-1048576
test:0 tp: 4 0-65536 0-65536 0-262144
test:0 tp: 5 0-32768 0-49152 0-65536
test:0 tp: 6 0-12288 0-12288 0-32768
test:0 tp: 7 0-6144 0-7168 0-8192
test:0 tp: 8 0-3072 0-3584 0-6144
test:0 tp: 9 384-1792 256-2240 0-2816
test:0 tp:10 704-1408 656-1424 448-1728
test:0 tp:11 880-1168 916-1140 704-1328
test:0 tp:12 930-1122 971-1076 916-1152
test:0 tp:13 905-1147 898-1165 971-1075
test:0 tp:14 889-1167 889-1166 898-1150
test:0 tp:15 891-1159 890-1164 0-263507
test:1 tp: 0 0-33554432 0-33554432 0-67108864
test:1 tp: 1 0-16777216 0-16777216 0-67108864
test:1 tp: 2 0-8388608 0-8388608 0-33554432
test:1 tp: 3 0-4194304 0-4194304 0-16777216
test:1 tp: 4 0-2097152 0-2097152 0-8388608
test:1 tp: 5 0-1048576 0-1048576 0-4194304
test:1 tp: 6 0-524288 0-1048576 0-2097152
test:1 tp: 7 0-262144 0-262144 0-1048576
test:1 tp: 8 0-262144 0-262144 0-524288
test:1 tp: 9 0-131072 0-131072 0-262144
test:1 tp:10 0-65536 0-65536 0-262144
test:1 tp:11 0-32768 0-49152 0-131072
test:1 tp:12 0-24576 0-32768 0-65536
test:1 tp:13 0-16384 0-24576 0-32768
test:1 tp:14 0-10240 0-10240 0-24576
test:1 tp:15 0-8192 0-7168 0-16384
test:1 tp:16 0-5120 0-5120 0-10240
test:1 tp:17 0-3584 0-4096 0-6144
test:1 tp:18 0-2560 0-3456 0-4608
test:1 tp:19 256-2112 192-2304 0-4096
test:1 tp:20 416-1792 352-1856 0-2816
test:1 tp:21 624-1552 576-1552 128-2176
test:1 tp:22 744-1368 688-1376 416-1760
test:1 tp:23 796-1276 780-1244 640-1424
test:1 tp:24 822-1232 866-1202 736-1352
test:1 tp:25 889-1176 911-1137 804-1244
test:1 tp:26 864-1173 902-1141 856-1174
test:1 tp:27 891-1170 894-1155 923-1115
test:1 tp:28 891-1156 897-1155 899-1155
test:1 tp:29 898-1181 883-1160 902-1161
test:1 tp:30 897-1167 897-1178 876-1173
test:1 tp:31 900-1177 896-1164 0-67108864
test:2 tp: 0 1024-1024 1024-1024 0-4096
test:2 tp: 1 1024-1024 1024-1024 0-2048
test:2 tp: 2 1024-1024 1024-1024 1024-1024
test:2 tp: 3 1024-1024 1024-1024 1024-1024
test:2 tp: 4 1024-1024 1024-1024 1024-1024
test:2 tp: 5 1024-1024 1024-1024 1024-1024
test:2 tp: 6 1024-1024 1024-1024 1024-1024
test:2 tp: 7 1024-1024 1024-1024 1024-1024
test:2 tp: 8 1024-1024 1024-1024 1024-1024
test:2 tp: 9 1024-1024 1024-1024 1024-1024
test:2 tp:10 1024-1024 1024-1024 1024-1024
test:2 tp:11 906-1142 928-1120 1024-1024
test:2 tp:12 894-1135 891-1142 1024-1024
test:2 tp:13 900-1170 899-1157 934-1114
test:2 tp:14 881-1159 900-1165 910-1139
test:2 tp:15 897-1153 893-1179 900-1163
test:2 tp:16 877-1168 888-1171 0-2236
test:3 tp: 0 0-33554425 0-33554425 0-67108849
test:3 tp: 1 0-16777213 0-16777213 0-67108849
test:3 tp: 2 0-8388607 0-8388607 0-33554425
test:3 tp: 3 0-4194304 0-4194304 0-16777213
test:3 tp: 4 0-2097152 0-2097152 0-8388607
test:3 tp: 5 0-1048576 0-1048576 0-4194304
test:3 tp: 6 0-524288 0-524288 0-2097152
test:3 tp: 7 0-262144 0-262144 0-1048576
test:3 tp: 8 0-131072 0-131072 0-524288
test:3 tp: 9 0-131072 0-131072 0-262144
test:3 tp:10 0-65536 0-65536 0-131072
test:3 tp:11 0-32768 0-32768 0-131072
test:3 tp:12 0-24576 0-24576 0-65536
test:3 tp:13 0-16384 0-20480 0-49152
test:3 tp:14 0-12288 0-10240 0-24576
test:3 tp:15 0-9216 0-6144 0-12288
test:3 tp:16 0-4608 0-4608 0-10240
test:3 tp:17 0-3328 0-3840 0-7168
test:3 tp:18 0-2560 0-2560 0-4608
test:3 tp:19 192-2240 128-2176 0-3840
test:3 tp:20 384-1888 352-1792 0-2432
test:3 tp:21 560-1584 624-1504 192-2176
test:3 tp:22 656-1400 696-1336 448-1824
test:3 tp:23 756-1296 828-1252 512-1632
test:3 tp:24 806-1272 888-1178 632-1432
test:3 tp:25 934-1134 929-1124 708-1316
test:3 tp:26 914-1138 914-1133 786-1274
test:3 tp:27 897-1152 906-1159 920-1128
test:3 tp:28 883-1175 902-1160 891-1156
test:3 tp:29 864-1160 897-1160 892-1171
test:3 tp:30 898-1200 895-1157 894-1164
test:3 tp:31 884-1196 890-1155 0-67108850
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
The educated differ from the uneducated as much as the living from the
dead. -- Aristotle
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