| /* |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| #include "libavutil/log.h" |
| #include "libavutil/timer.h" |
| #include "libavutil/lfg.h" |
| |
| int main(void) |
| { |
| int x = 0; |
| int i, j; |
| AVLFG state; |
| |
| av_lfg_init(&state, 0xdeadbeef); |
| for (j = 0; j < 10000; j++) { |
| START_TIMER |
| for (i = 0; i < 624; i++) { |
| //av_log(NULL, AV_LOG_ERROR, "%X\n", av_lfg_get(&state)); |
| x += av_lfg_get(&state); |
| } |
| STOP_TIMER("624 calls of av_lfg_get"); |
| } |
| av_log(NULL, AV_LOG_ERROR, "final value:%X\n", x); |
| |
| /* BMG usage example */ |
| { |
| double mean = 1000; |
| double stddev = 53; |
| double samp_mean = 0.0, samp_stddev = 0.0; |
| double samp0, samp1; |
| |
| av_lfg_init(&state, 42); |
| |
| for (i = 0; i < 1000; i += 2) { |
| double bmg_out[2]; |
| av_bmg_get(&state, bmg_out); |
| samp0 = bmg_out[0] * stddev + mean; |
| samp1 = bmg_out[1] * stddev + mean; |
| samp_mean += samp0 + samp1; |
| samp_stddev += samp0 * samp0 + samp1 * samp1; |
| av_log(NULL, AV_LOG_INFO, |
| "%f\n%f\n", |
| samp0, |
| samp1); |
| } |
| /* TODO: add proper normality test */ |
| samp_mean /= 1000; |
| samp_stddev /= 999; |
| samp_stddev -= (1000.0/999.0)*samp_mean*samp_mean; |
| samp_stddev = sqrt(samp_stddev); |
| av_log(NULL, AV_LOG_INFO, "sample mean : %f\n" |
| "true mean : %f\n" |
| "sample stddev: %f\n" |
| "true stddev : %f\n", |
| samp_mean, mean, samp_stddev, stddev); |
| } |
| |
| return 0; |
| } |