var
  ONE_SECOND_IN_TS = 90000, // 90kHz clock
  secondsToVideoTs,
  secondsToAudioTs,
  videoTsToSeconds,
  audioTsToSeconds,
  audioTsToVideoTs,
  videoTsToAudioTs;

secondsToVideoTs = function(seconds) {
  return seconds * ONE_SECOND_IN_TS;
};

secondsToAudioTs = function(seconds, sampleRate) {
  return seconds * sampleRate;
};

videoTsToSeconds = function(timestamp) {
  return timestamp / ONE_SECOND_IN_TS;
};

audioTsToSeconds = function(timestamp, sampleRate) {
  return timestamp / sampleRate;
};

audioTsToVideoTs = function(timestamp, sampleRate) {
  return secondsToVideoTs(audioTsToSeconds(timestamp, sampleRate));
};

videoTsToAudioTs = function(timestamp, sampleRate) {
  return secondsToAudioTs(videoTsToSeconds(timestamp), sampleRate);
};

module.exports = {
  secondsToVideoTs: secondsToVideoTs,
  secondsToAudioTs: secondsToAudioTs,
  videoTsToSeconds: videoTsToSeconds,
  audioTsToSeconds: audioTsToSeconds,
  audioTsToVideoTs: audioTsToVideoTs,
  videoTsToAudioTs: videoTsToAudioTs
};