AssumeSampleRate
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[[AviSource]]("video_audio.avi") | [[AviSource]]("video_audio.avi") | ||
# Let's say that this clip loses audio sync: | # Let's say that this clip loses audio sync: | ||
| − | # | + | # by the end, the audio is behind by 200 milliseconds. |
| − | dur = | + | Ar = [[Clip_properties|AudioRate]] # original audio sample rate |
| − | adj = -0.200 | + | dur = [[Clip_properties|AudioDuration]] # total duration in seconds |
| − | + | adj = -0.200 # correction needed (decrease audio duration by 200 msec) | |
# Adjust audio duration: | # Adjust audio duration: | ||
Revision as of 14:39, 18 May 2016
AssumeSampleRate(clip clip, int samplerate)
Changes the sample rate of the current clip without changing the number of samples.
- This changes the pitch, playback speed and running time of the audio.
- It will also affect synchronization with the video.
Examples
- Fix an audio sync problem:
AviSource("video_audio.avi") # Let's say that this clip loses audio sync: # by the end, the audio is behind by 200 milliseconds. Ar = AudioRate # original audio sample rate dur = AudioDuration # total duration in seconds adj = -0.200 # correction needed (decrease audio duration by 200 msec) # Adjust audio duration: AssumeSampleRate(Round(dur / (dur+adj) * Ar)) # Restore original sample rate while retaining new duration; # this step is may be skipped if you don't mind a slightly nonstandard sample rate. ResampleAudio(Ar) # Video and audio are now in sync.
- Play video and audio at half speed:
AviSource("video_audio.avi") # Play video at half speed: audio will be out of sync AssumeFPS(FrameRate/2) # Play audio at half speed: (pitch will be lowered by an octave) AssumeSampleRate(AudioRate/2) # Video and audio are now in sync. # Equivalent to calling AssumeFPS(..., sync_audio=true) (see below)
See Also
- AssumeFPS: sync_audio
- If true, the audio sample rate is changed by the same amount; the pitch of the resulting audio is shifted.
- If false (the default), the audio is unchanged; this means the audio will lose synchronization over time.
