RepoMirrors/mpv
1
0
Fork 0
mirror of https://github.com/mpv-player/mpv synced 2025-03-20 02:09:52 +00:00
Code Issues Releases Wiki Activity

af_scaletempo2: fix audio artifact on initial WSOLA iteration

Browse Source 
The first WSOLA iteration overlapped audio with whatever was in the
`wsola_output` buffer. This was either silence (if not run before), or
old frames (if switching to 1x and back to a different speed).

Track the state of the output buffer and memcpy the whole window for the
first iteration instead.
This commit is contained in:
ferreum 2023-08-08 12:50:39 +02:00 committed by Niklas Haas
parent c3bceb3243
commit 33d6d0f311
2 changed files with 20 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
audio/filter/af_scaletempo2_internals.c
View File

@ -620,17 +620,24 @@ static bool run_one_wsola_iteration(struct mp_scaletempo2 *p, float playback_rat
for (int k = 0; k < p->channels; ++k) {
float* ch_opt_frame = p->optimal_block[k];
float* ch_output = p->wsola_output[k] + p->num_complete_frames;
for (int n = 0; n < p->ola_hop_size; ++n) {
ch_output[n] = ch_output[n] * p->ola_window[p->ola_hop_size + n] +
ch_opt_frame[n] * p->ola_window[n];
}
if (p->wsola_output_started) {
for (int n = 0; n < p->ola_hop_size; ++n) {
ch_output[n] = ch_output[n] * p->ola_window[p->ola_hop_size + n] +
ch_opt_frame[n] * p->ola_window[n];
}
// Copy the second half to the output.
memcpy(&ch_output[p->ola_hop_size], &ch_opt_frame[p->ola_hop_size],
sizeof(*ch_opt_frame) * p->ola_hop_size);
// Copy the second half to the output.
memcpy(&ch_output[p->ola_hop_size], &ch_opt_frame[p->ola_hop_size],
sizeof(*ch_opt_frame) * p->ola_hop_size);
} else {
// No overlap for the first iteration.
memcpy(ch_output, ch_opt_frame,
sizeof(*ch_opt_frame) * p->ola_window_size);
}
}
p->num_complete_frames += p->ola_hop_size;
p->wsola_output_started = true;
update_output_time(p, playback_rate, p->ola_hop_size);
remove_old_input_frames(p, playback_rate);
return true;
@ -686,6 +693,7 @@ int mp_scaletempo2_fill_buffer(struct mp_scaletempo2 *p,
// Optimize the most common |playback_rate| ~= 1 case to use a single copy
// instead of copying frame by frame.
if (p->ola_window_size <= faster_step && slower_step >= p->ola_window_size) {
p->wsola_output_started = false;
return read_input_buffer(p, dest_size, dest);
}
@ -730,6 +738,7 @@ void mp_scaletempo2_reset(struct mp_scaletempo2 *p)
// Clear the queue of decoded packets.
zero_2d(p->wsola_output, p->channels, p->wsola_output_size);
p->num_complete_frames = 0;
p->wsola_output_started = false;
}
// Return a "periodic" Hann window. This is the first L samples of an L+1
@ -748,6 +757,7 @@ void mp_scaletempo2_init(struct mp_scaletempo2 *p, int channels, int rate)
p->search_block_center_offset = 0;
p->search_block_index = 0;
p->num_complete_frames = 0;
p->wsola_output_started = false;
p->channels = channels;
p->samples_per_second = rate;

3
audio/filter/af_scaletempo2_internals.h
View File

@ -80,6 +80,9 @@ struct mp_scaletempo2 {
// them and can be copied to output if fill_buffer() is called. It also
// specifies the index where the next WSOLA window has to overlap-and-add.
int num_complete_frames;
// Whether |wsola_output| contains an additional |ola_hop_size| of overlap
// frames for the next iteration.
bool wsola_output_started;
// Overlap-and-add window.
float *ola_window;
// Transition window, used to update |optimal_block| by a weighted sum of