From cf8b7ff0d666a4c13b32d8d9e973435df419b5ef Mon Sep 17 00:00:00 2001 From: ferreum Date: Thu, 17 Aug 2023 17:11:25 +0200 Subject: af_scaletempo2: calculate latency by center of search block 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. --- audio/filter/af_scaletempo2_internals.c | 9 ++++----- audio/filter/af_scaletempo2_internals.h | 3 ++- 2 files changed, 6 insertions(+), 6 deletions(-) diff --git a/audio/filter/af_scaletempo2_internals.c b/audio/filter/af_scaletempo2_internals.c index eb2d4bb20b..a9d0fba136 100644 --- a/audio/filter/af_scaletempo2_internals.c +++ b/audio/filter/af_scaletempo2_internals.c @@ -707,7 +707,7 @@ int mp_scaletempo2_fill_buffer(struct mp_scaletempo2 *p, p->wsola_output_started = false; // 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); } @@ -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) { - return p->input_buffer_frames - p->search_block_index + return p->input_buffer_frames - p->output_time + 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) { p->input_buffer_frames = 0; - p->output_time = p->search_block_center_offset; + p->output_time = 0.0; p->search_block_index = 0; p->target_block_index = 0; // 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) { p->muted_partial_frame = 0; + p->output_time = 0; p->search_block_center_offset = 0; p->search_block_index = 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); 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 = realloc_2d(p->wsola_output, p->channels, p->wsola_output_size); // Initialize for overlap-and-add of the first block. diff --git a/audio/filter/af_scaletempo2_internals.h b/audio/filter/af_scaletempo2_internals.h index f1b74ec64f..622d6e20da 100644 --- a/audio/filter/af_scaletempo2_internals.h +++ b/audio/filter/af_scaletempo2_internals.h @@ -64,7 +64,8 @@ struct mp_scaletempo2 { double output_time; // The offset of the center frame of |search_block| w.r.t. its first frame. 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; // Number of Blocks to search to find the most similar one to the target // frame. -- cgit v1.2.3