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af_scaletempo2: calculate latency by center of search block

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This changes the emitted pts values from the start of the search block
to the center of the search block. Change initial `output_time`
accordingly. Initial `search_block_index` is irrelevant, because it's
overwritten before the first iteration.

Using the `output_time` removes the rounding of `search_block_index`,
which also fixes the <20 microsecond gaps in timestamps between output
packets.

Rationale:

The variance in audio position was in the range `0..search-interval`.

With this change, the range is

    (- search-interval / 2)..(search-interval / 2)`

which ensures lower maximum offset.
This commit is contained in:
ferreum 2023-08-17 17:11:25 +02:00 committed by Niklas Haas
parent c0728249a1
commit cf8b7ff0d6
2 changed files with 6 additions and 6 deletions
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9
audio/filter/af_scaletempo2_internals.c
View File

@ -707,7 +707,7 @@ int mp_scaletempo2_fill_buffer(struct mp_scaletempo2 *p,
p->wsola_output_started = false; p->wsola_output_started = false;
// sync audio precisely again // sync audio precisely again
set_output_time(p, p->target_block_index + p->search_block_center_offset); set_output_time(p, p->target_block_index);
remove_old_input_frames(p); remove_old_input_frames(p);
} }
@ -725,7 +725,7 @@ int mp_scaletempo2_fill_buffer(struct mp_scaletempo2 *p,
double mp_scaletempo2_get_latency(struct mp_scaletempo2 *p, double playback_rate) double mp_scaletempo2_get_latency(struct mp_scaletempo2 *p, double playback_rate)
{ {
return p->input_buffer_frames - p->search_block_index return p->input_buffer_frames - p->output_time
+ p->num_complete_frames * playback_rate; + p->num_complete_frames * playback_rate;
} }
@ -749,7 +749,7 @@ void mp_scaletempo2_destroy(struct mp_scaletempo2 *p)
void mp_scaletempo2_reset(struct mp_scaletempo2 *p) void mp_scaletempo2_reset(struct mp_scaletempo2 *p)
{ {
p->input_buffer_frames = 0; p->input_buffer_frames = 0;
p->output_time = p->search_block_center_offset; p->output_time = 0.0;
p->search_block_index = 0; p->search_block_index = 0;
p->target_block_index = 0; p->target_block_index = 0;
// Clear the queue of decoded packets. // Clear the queue of decoded packets.
@ -771,6 +771,7 @@ static void get_symmetric_hanning_window(int window_length, float* window)
void mp_scaletempo2_init(struct mp_scaletempo2 *p, int channels, int rate) void mp_scaletempo2_init(struct mp_scaletempo2 *p, int channels, int rate)
{ {
p->muted_partial_frame = 0; p->muted_partial_frame = 0;
p->output_time = 0;
p->search_block_center_offset = 0; p->search_block_center_offset = 0;
p->search_block_index = 0; p->search_block_index = 0;
p->num_complete_frames = 0; p->num_complete_frames = 0;
@ -813,8 +814,6 @@ void mp_scaletempo2_init(struct mp_scaletempo2 *p, int channels, int rate)
sizeof(float) * p->ola_window_size * 2); sizeof(float) * p->ola_window_size * 2);
get_symmetric_hanning_window(2 * p->ola_window_size, p->transition_window); get_symmetric_hanning_window(2 * p->ola_window_size, p->transition_window);
p->output_time = p->search_block_center_offset;
p->wsola_output_size = p->ola_window_size + p->ola_hop_size; p->wsola_output_size = p->ola_window_size + p->ola_hop_size;
p->wsola_output = realloc_2d(p->wsola_output, p->channels, p->wsola_output_size); p->wsola_output = realloc_2d(p->wsola_output, p->channels, p->wsola_output_size);
// Initialize for overlap-and-add of the first block. // Initialize for overlap-and-add of the first block.

3
audio/filter/af_scaletempo2_internals.h
View File

@ -64,7 +64,8 @@ struct mp_scaletempo2 {
double output_time; double output_time;
// The offset of the center frame of |search_block| w.r.t. its first frame. // The offset of the center frame of |search_block| w.r.t. its first frame.
int search_block_center_offset; int search_block_center_offset;
// Index of the beginning of the |search_block|, in frames. // Index of the beginning of the |search_block|, in frames. This may be
// negative, which is handled by |peek_audio_with_zero_prepend|.
int search_block_index; int search_block_index;
// Number of Blocks to search to find the most similar one to the target // Number of Blocks to search to find the most similar one to the target
// frame. // frame.