diff options
Diffstat (limited to 'libs/ardour/ardour/audio_diskstream.h')
| -rw-r--r-- | libs/ardour/ardour/audio_diskstream.h | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/libs/ardour/ardour/audio_diskstream.h b/libs/ardour/ardour/audio_diskstream.h index f918655f98..0db44709f8 100644 --- a/libs/ardour/ardour/audio_diskstream.h +++ b/libs/ardour/ardour/audio_diskstream.h @@ -150,6 +150,48 @@ class AudioDiskstream : public Diskstream XMLNode* deprecated_io_node; + /** + * Calculate the playback distance during varispeed playback. + * Important for Session::process to know exactly, how many frames + * were passed by. + */ + static nframes_t calculate_varispeed_playback_distance( + nframes_t nframes, + uint64_t& the_last_phase, + uint64_t& the_phi, + uint64_t& the_target_phi) + { + // calculate playback distance in the same way + // as in AudioDiskstream::process_varispeed_playback + uint64_t phase = the_last_phase; + int64_t phi_delta; + nframes_t i = 0; + + const int64_t fractional_part_mask = 0xFFFFFF; + const Sample binary_scaling_factor = 16777216.0f; + + if (the_phi != the_target_phi) { + phi_delta = ((int64_t)(the_target_phi - the_phi)) / nframes; + } else { + phi_delta = 0; + } + + Sample fractional_phase_part; + + i = 0; + phase = the_last_phase; + + for (nframes_t outsample = 0; outsample < nframes; ++outsample) { + i = phase >> 24; + fractional_phase_part = (phase & fractional_part_mask) / binary_scaling_factor; + phase += the_phi + phi_delta; + } + + the_last_phase = (phase & fractional_part_mask); + the_phi = the_target_phi; + return i; // + 1; + } + protected: friend class Session; |