Hi folks.

I'm generating an HD video file (.m2t, 720x480 NTSC), and the audio slowly loses synch with the video. They are synchronized at the start, but by the end (53 minutes), the video lags the audio by a second or two.

Is there a way to fix this during rendering? If not, is there a way to fix it after the fact?

Thanks!

We have seen this sort of problem with DV with unlocked audio, but not yet with HDV. I wonder if there is a similar problem because this unlocked audio problem stems from consumer camcorders. There is a way to fix it after the fact, but kinda hard. Basically, you have to render the project as WAV, count the number of samples, determine what the correct number should be based on the project duration. Then, use the following formula:
adjustedRate = outputRate + ( idealSamples - actualSamples ) / seconds

where seconds is the project duration including a few decimal points of precision. The outputRate is the sampling rate (usually 44100 or 48000). The adjustedRate is a new sample rate to use with an audio resampler. Then, you resample, but the next step is even harder. You do not want the new audio file to indicate adjustedRate; you must somehow force it to indicate the outputRate. Finally, you mute or remove the original audio in Kdenlive and bring the adjusted audio clip into Kdenlive and render a final output.

I left out some specific details of how to accomplish some steps because I do not know them off-hand - I would have to figure them out again.

Thanks for the info.

So, this is a known bug? Rendering it with different options or in a different format won't help?

This is a known bug with DV sources with unlocked audio. It is not a known problem for HDV, but I will test for it with my Canon HV20.