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Commit 7df2882b authored by Stefan Westerfeld's avatar Stefan Westerfeld
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Add function for sync threshold selection. 

Signed-off-by: Stefan Westerfeld's avatarStefan Westerfeld <stefan@space.twc.de>
parent 0413b00d
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Showing with 57 additions and 97 deletions
src/wmget.cc
View file @ 7df2882b
......@@ -360,7 +360,6 @@ private:
// compute multiple time-shifted fft vectors
size_t n_bands = Params::max_band - Params::min_band + 1;
int total_frame_count = mark_sync_frame_count() + mark_data_frame_count();
const int first_block_end = total_frame_count;
if (mode == Mode::CLIP)
total_frame_count *= 2;
for (size_t sync_shift = 0; sync_shift < Params::frame_size; sync_shift += Params::sync_search_step)
......@@ -381,6 +380,40 @@ private:
sort (sync_scores.begin(), sync_scores.end(), [] (const Score& a, const Score &b) { return a.index < b.index; });
return sync_scores;
}
void
sync_select_by_threshold (vector<Score>& sync_scores)
{
/* for strength 8 and above:
* -> more false positive candidates are rejected, so we can use a lower threshold
*
* for strength 7 and below:
* -> we need a higher threshold, because otherwise watermark detection takes too long
*/
const double strength = Params::water_delta * 1000;
const double sync_threshold1 = strength > 7.5 ? 0.4 : 0.5;
vector<Score> selected_scores;
for (size_t i = 0; i < sync_scores.size(); i++)
{
if (sync_scores[i].quality > sync_threshold1)
{
double q_last = -1;
double q_next = -1;
if (i > 0)
q_last = sync_scores[i - 1].quality;
if (i + 1 < sync_scores.size())
q_next = sync_scores[i + 1].quality;
if (sync_scores[i].quality > q_last && sync_scores[i].quality > q_next)
{
selected_scores.emplace_back (sync_scores[i]);
}
}
}
sync_scores = selected_scores;
}
size_t wav_data_start = 0;
size_t wav_data_end = 0;
......@@ -420,33 +453,8 @@ public:
wav_data_end = 0;
}
vector<Score> sync_scores = search_approx (wav_data, mode);
#if 0
vector<float> fft_db;
vector<char> have_frame;
// compute multiple time-shifted fft vectors
size_t n_bands = Params::max_band - Params::min_band + 1;
int total_frame_count = mark_sync_frame_count() + mark_data_frame_count();
const int first_block_end = total_frame_count;
if (mode == Mode::CLIP)
total_frame_count *= 2;
for (size_t sync_shift = 0; sync_shift < Params::frame_size; sync_shift += Params::sync_search_step)
{
sync_fft (wav_data, sync_shift, frame_count (wav_data) - 1, fft_db, have_frame, /* want all frames */ {});
for (int start_frame = 0; start_frame < frame_count (wav_data); start_frame++)
{
const size_t sync_index = start_frame * Params::frame_size + sync_shift;
if ((start_frame + total_frame_count) * wav_data.n_channels() * n_bands < fft_db.size())
{
ConvBlockType block_type;
double quality = sync_decode (wav_data, start_frame, fft_db, have_frame, &block_type);
// printf ("%zd %f\n", sync_index, quality);
sync_scores.emplace_back (Score { sync_index, quality, block_type });
}
}
}
sort (sync_scores.begin(), sync_scores.end(), [] (const Score& a, const Score &b) { return a.index < b.index; });
#endif
sync_select_by_threshold (sync_scores);
int total_frame_count = mark_sync_frame_count() + mark_data_frame_count();
const int first_block_end = total_frame_count;
......@@ -460,93 +468,45 @@ public:
want_frames[first_block_end + sync_frame_pos (f)] = 1;
}
/* for strength 8 and above:
* -> more false positive candidates are rejected, so we can use a lower threshold
*
* for strength 7 and below:
* -> we need a higher threshold, because otherwise watermark detection takes too long
*/
const double strength = Params::water_delta * 1000;
const double sync_threshold1 = strength > 7.5 ? 0.4 : 0.5;
/* n-best-search */
struct NBest {
size_t i;
double quality;
};
vector<NBest> n_best;
for (size_t i = 0; i < sync_scores.size(); i++)
{
if (sync_scores[i].quality > sync_threshold1)
{
double q_last = -1;
double q_next = -1;
if (i > 0)
q_last = sync_scores[i - 1].quality;
if (i + 1 < sync_scores.size())
q_next = sync_scores[i + 1].quality;
if (sync_scores[i].quality > q_last && sync_scores[i].quality > q_next)
{
n_best.push_back ({ i, sync_scores[i].quality });
}
}
}
vector<Score> n_best = sync_scores;
if (mode == Mode::CLIP)
{
std::sort (n_best.begin(), n_best.end(), [](NBest& nb1, NBest& nb2) { return nb1.quality > nb2.quality; });
std::sort (n_best.begin(), n_best.end(), [](Score& nb1, Score& nb2) { return nb1.quality > nb2.quality; });
if (n_best.size() > 5)
n_best.resize (5);
}
vector<float> fft_db;
vector<char> have_frame;
for (auto n : n_best)
for (const auto& score : n_best)
{
size_t i = n.i;
//printf ("%d %zd %f %d\n", int (block_length), sync_scores[i].index, sync_scores[i].quality, sync_scores[i].len);
if (sync_scores[i].quality > sync_threshold1)
{
double q_last = -1;
double q_next = -1;
if (i > 0)
q_last = sync_scores[i - 1].quality;
//printf ("%zd %s %f", sync_scores[i].index, find_closest_sync (sync_scores[i].index), sync_scores[i].quality);
if (i + 1 < sync_scores.size())
q_next = sync_scores[i + 1].quality;
// refine match
double best_quality = score.quality;
size_t best_index = score.index;
ConvBlockType best_block_type = score.block_type; /* doesn't really change during refinement */
if (sync_scores[i].quality > q_last && sync_scores[i].quality > q_next)
int start = std::max (int (score.index) - Params::sync_search_step, 0);
int end = score.index + Params::sync_search_step;
for (int fine_index = start; fine_index <= end; fine_index += Params::sync_search_fine)
{
sync_fft (wav_data, fine_index, total_frame_count, fft_db, have_frame, want_frames);
if (fft_db.size())
{
//printf ("%zd %s %f", sync_scores[i].index, find_closest_sync (sync_scores[i].index), sync_scores[i].quality);
// refine match
double best_quality = sync_scores[i].quality;
size_t best_index = sync_scores[i].index;
ConvBlockType best_block_type = sync_scores[i].block_type; /* doesn't really change during refinement */
ConvBlockType block_type;
double q = sync_decode (wav_data, 0, fft_db, have_frame, &block_type);
int start = std::max (int (sync_scores[i].index) - Params::sync_search_step, 0);
int end = sync_scores[i].index + Params::sync_search_step;
for (int fine_index = start; fine_index <= end; fine_index += Params::sync_search_fine)
if (q > best_quality)
{
sync_fft (wav_data, fine_index, total_frame_count, fft_db, have_frame, want_frames);
if (fft_db.size())
{
ConvBlockType block_type;
double q = sync_decode (wav_data, 0, fft_db, have_frame, &block_type);
if (q > best_quality)
{
best_quality = q;
best_index = fine_index;
}
}
best_quality = q;
best_index = fine_index;
}
//printf (" => refined: %zd %s %f\n", best_index, find_closest_sync (best_index), best_quality);
if (best_quality > Params::sync_threshold2)
result_scores.push_back (Score { best_index, best_quality, best_block_type });
}
}
//printf (" => refined: %zd %s %f\n", best_index, find_closest_sync (best_index), best_quality);
if (best_quality > Params::sync_threshold2)
result_scores.push_back (Score { best_index, best_quality, best_block_type });
}
return result_scores;
}
......
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