Advanced Member
Group: Members
Posts: 35
Member No.: 35896
Joined: 26-December 12
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When using Time Stretch ratio values like 0.9990233813982881, periodic clicks creep into the audio. Other than that, the sound is good. This can be heard using the Test button in the Audio Filters dialog, as well as in Ouptut Playback and in the actual output AVI played in VLC Player. I haven't tried uploading to YouTube, Facebook, etc. to see what they make of it.
I'm doing this for the purpose of A/V sync, correcting videos recorded with slightly slow video and/or slightly fast audio. If there's a better way, please let me know. I tried New Rate and it sounded horrible when I typed in an arbitrary rate (44143 in this case).
The number above is computed with the A/V Sync calculator I linked to in a previous forum post, and it's derived by manually correlating two events between audio and video. In the case of the video I'm working on now, there's no skew, so the first event is simply (0, 0). Other videos I worked on were not so easy.
Here's a before-and-after comparison so you can hear for yourself:
Before applying filter
After applying filter
I tried doing the same speed adjustment in Audacity using the Change Tempo filter, and it sounded much better. This filter is implemented using libsamplerate, which uses the GPL. This might be a good thing to put in VirtualDub. |
