diff options
Diffstat (limited to 'src/lib/audio_content.cc')
| -rw-r--r-- | src/lib/audio_content.cc | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/src/lib/audio_content.cc b/src/lib/audio_content.cc index b4c4f34b6..3c0d13ba9 100644 --- a/src/lib/audio_content.cc +++ b/src/lib/audio_content.cc @@ -40,7 +40,7 @@ int const AudioContentProperty::AUDIO_GAIN = 203; int const AudioContentProperty::AUDIO_DELAY = 204; int const AudioContentProperty::AUDIO_MAPPING = 205; -AudioContent::AudioContent (shared_ptr<const Film> f, Time s) +AudioContent::AudioContent (shared_ptr<const Film> f, DCPTime s) : Content (f, s) , _audio_gain (0) , _audio_delay (Config::instance()->default_audio_delay ()) @@ -149,3 +149,27 @@ AudioContent::technical_summary () const { return String::compose ("audio: channels %1, length %2, raw rate %3, out rate %4", audio_channels(), audio_length(), content_audio_frame_rate(), output_audio_frame_rate()); } + +/** Note: this is not particularly fast, as the FrameRateChange lookup + * is not very intelligent. + * + * @param t Some duration to convert. + * @param at The time within the DCP to get the active frame rate change from; i.e. a point at which + * the `controlling' video content is active. + */ +AudioFrame +AudioContent::time_to_content_audio_frames (DCPTime t, DCPTime at) const +{ + shared_ptr<const Film> film = _film.lock (); + assert (film); + + /* Consider the case where we're running a 25fps video at 24fps (i.e. slow) + Our audio is at 44.1kHz. We will resample it to 48000 * 25 / 24 and then + run it at 48kHz (i.e. slow, to match). + + After 1 second, we'll have run the equivalent of 44.1kHz * 24 / 25 samples + in the source. + */ + + return rint (t * content_audio_frame_rate() * film->active_frame_rate_change(at).speed_up / TIME_HZ); +} |