tor-browser

boolcoder_test.cc (6400B)

---

/*
* Copyright (c) 2016, Alliance for Open Media. All rights reserved.
*
* This source code is subject to the terms of the BSD 2 Clause License and
* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
* was not distributed with this source code in the LICENSE file, you can
* obtain it at www.aomedia.org/license/software. If the Alliance for Open
* Media Patent License 1.0 was not distributed with this source code in the
* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
*/

#include <math.h>
#include <stdlib.h>
#include <string.h>

#include "gtest/gtest.h"

#include "test/acm_random.h"
#include "aom/aom_integer.h"
#include "aom_dsp/bitreader.h"
#include "aom_dsp/bitwriter.h"

using libaom_test::ACMRandom;

namespace {
const int num_tests = 10;
}  // namespace

TEST(AV1, TestBitIO) {
 ACMRandom rnd(ACMRandom::DeterministicSeed());
 for (int n = 0; n < num_tests; ++n) {
   for (int method = 0; method <= 7; ++method) {  // we generate various proba
     const int kBitsToTest = 1000;
     uint8_t probas[kBitsToTest];

     for (int i = 0; i < kBitsToTest; ++i) {
       const int parity = i & 1;
       /* clang-format off */
       probas[i] =
         (method == 0) ? 0 : (method == 1) ? 255 :
         (method == 2) ? 128 :
         (method == 3) ? rnd.Rand8() :
         (method == 4) ? (parity ? 0 : 255) :
           // alternate between low and high proba:
           (method == 5) ? (parity ? rnd(128) : 255 - rnd(128)) :
           (method == 6) ?
           (parity ? rnd(64) : 255 - rnd(64)) :
           (parity ? rnd(32) : 255 - rnd(32));
       /* clang-format on */
     }
     for (int bit_method = 0; bit_method <= 3; ++bit_method) {
       const int random_seed = 6432;
       const int kBufferSize = 10000;
       ACMRandom bit_rnd(random_seed);
       aom_writer bw;
       uint8_t bw_buffer[kBufferSize];
       aom_start_encode(&bw, bw_buffer);

       int bit = (bit_method == 0) ? 0 : (bit_method == 1) ? 1 : 0;
       for (int i = 0; i < kBitsToTest; ++i) {
         if (bit_method == 2) {
           bit = (i & 1);
         } else if (bit_method == 3) {
           bit = bit_rnd(2);
         }
         aom_write(&bw, bit, static_cast<int>(probas[i]));
       }

       GTEST_ASSERT_GE(aom_stop_encode(&bw), 0);

       aom_reader br;
       aom_reader_init(&br, bw_buffer, bw.pos);
       bit_rnd.Reset(random_seed);
       for (int i = 0; i < kBitsToTest; ++i) {
         if (bit_method == 2) {
           bit = (i & 1);
         } else if (bit_method == 3) {
           bit = bit_rnd(2);
         }
         GTEST_ASSERT_EQ(aom_read(&br, probas[i], nullptr), bit)
             << "pos: " << i << " / " << kBitsToTest
             << " bit_method: " << bit_method << " method: " << method;
       }
     }
   }
 }
}

#define FRAC_DIFF_TOTAL_ERROR 0.18

TEST(AV1, TestTell) {
 const int kBufferSize = 10000;
 aom_writer bw;
 uint8_t bw_buffer[kBufferSize];
 const int kSymbols = 1024;
 // Coders are noisier at low probabilities, so we start at p = 4.
 for (int p = 4; p < 256; p++) {
   double probability = p / 256.;
   aom_start_encode(&bw, bw_buffer);
   for (int i = 0; i < kSymbols; i++) {
     aom_write(&bw, 0, p);
   }
   GTEST_ASSERT_GE(aom_stop_encode(&bw), 0);
   aom_reader br;
   aom_reader_init(&br, bw_buffer, bw.pos);
   uint32_t last_tell = aom_reader_tell(&br);
   uint32_t last_tell_frac = aom_reader_tell_frac(&br);
   double frac_diff_total = 0;
   GTEST_ASSERT_GE(aom_reader_tell(&br), 0u);
   GTEST_ASSERT_LE(aom_reader_tell(&br), 1u);
   ASSERT_FALSE(aom_reader_has_overflowed(&br));
   for (int i = 0; i < kSymbols; i++) {
     aom_read(&br, p, nullptr);
     uint32_t tell = aom_reader_tell(&br);
     uint32_t tell_frac = aom_reader_tell_frac(&br);
     GTEST_ASSERT_GE(tell, last_tell)
         << "tell: " << tell << ", last_tell: " << last_tell;
     GTEST_ASSERT_GE(tell_frac, last_tell_frac)
         << "tell_frac: " << tell_frac
         << ", last_tell_frac: " << last_tell_frac;
     // Frac tell should round up to tell.
     GTEST_ASSERT_EQ(tell, (tell_frac + 7) >> 3);
     last_tell = tell;
     frac_diff_total +=
         fabs(((tell_frac - last_tell_frac) / 8.0) + log2(probability));
     last_tell_frac = tell_frac;
   }
   const uint32_t expected = (uint32_t)(-kSymbols * log2(probability));
   // Last tell should be close to the expected value.
   GTEST_ASSERT_LE(last_tell, expected + 20) << " last_tell: " << last_tell;
   // The average frac_diff error should be pretty small.
   GTEST_ASSERT_LE(frac_diff_total / kSymbols, FRAC_DIFF_TOTAL_ERROR)
       << " frac_diff_total: " << frac_diff_total;
   ASSERT_FALSE(aom_reader_has_overflowed(&br));
 }
}

TEST(AV1, TestHasOverflowed) {
 const int kBufferSize = 10000;
 aom_writer bw;
 uint8_t bw_buffer[kBufferSize];
 const int kSymbols = 1024;
 // Coders are noisier at low probabilities, so we start at p = 4.
 for (int p = 4; p < 256; p++) {
   aom_start_encode(&bw, bw_buffer);
   for (int i = 0; i < kSymbols; i++) {
     aom_write(&bw, 1, p);
   }
   GTEST_ASSERT_GE(aom_stop_encode(&bw), 0);
   aom_reader br;
   aom_reader_init(&br, bw_buffer, bw.pos);
   ASSERT_FALSE(aom_reader_has_overflowed(&br));
   for (int i = 0; i < kSymbols; i++) {
     GTEST_ASSERT_EQ(aom_read(&br, p, nullptr), 1);
     ASSERT_FALSE(aom_reader_has_overflowed(&br));
   }
   // In the worst case, the encoder uses just a tiny fraction of the last
   // byte in the buffer. So to guarantee that aom_reader_has_overflowed()
   // returns true, we have to consume very nearly 8 additional bits of data.
   // In the worse case, one of the bits in that byte will be 1, and the rest
   // will be zero. Once we are past that 1 bit, when the probability of
   // reading zero symbol from aom_read() is high, each additional symbol read
   // will consume very little additional data (in the case that p == 255,
   // approximately -log_2(255/256) ~= 0.0056 bits). In that case it would
   // take around 178 calls to consume more than 8 bits. That is only an upper
   // bound. In practice we are not guaranteed to hit the worse case and can
   // get away with 174 calls.
   for (int i = 0; i < 174; i++) {
     aom_read(&br, p, nullptr);
   }
   ASSERT_TRUE(aom_reader_has_overflowed(&br));
 }
}