It’s been a while since I’ve updated my blog. I didn’t encounter any weird things until last week.
At Movideo, we’ve been haunted by videos that goes out of sync with it’s audio. The symptom goes something like this:
- Plays a dynamic bitrate video that was encoded using Movideo’s Encoder application.
- In the beginning, audio and video is in sync.
- A crackling noise appeared and then the audio and video goes out of sync.
We’ve decided to use MEncoder to normalize the original video which is in .mov format.
mencoder -ovc copy -af volnorm=1 -oac libmp3lame input.mov -o output.mov
creates a mov file which Quick Time won’t recognize at all. Tried viewing it with Windows Media Player and there’s audio but no video. After that, I upload the video via Movideo’s Admin interface. The re-encoded video still goes out of sync.
The solution to this is to re-encode the audio with FFmpeg with
ffmpeg -i input.mov -vcodec copy -acodec libmp3lame output.mov
Now, output.mov can be viewed by Quick Time and works fine on Windows Media Player. Then, I tried uploading the output.mov via Movideo’s Admin interface and the video doesn’t go out of sync anymore.