Wednesday, February 20, 2013

Finally starting on editing the nest video from Cstone 2012, some issues.

Decided to start to edit a band I was going to wait a while on, The Choir.

I was going to do some more smaller set bands with less editing requirements because their set was shorter, but decided to try to get The Choir done.

Imported the audio and video clips, and started synching the audio with the recording I made.

Ran into a problem or glitch which I didn't notice or perhaps worked around somewhat differently.

I looks like the audio and video are drifting out on sync for this footage, meaning the audio on the video tracks and video on those match, but my master audio track was not transcoded correctly into the 48kilohertz sample rate correctly. Normally Media 100 will import the sampled audio and transcode it to the sample rate you select. I didn't do anything out of the ordinary as far as I can tell. Unfortunately I left the audio recorder at 44.1k sample rate while recording all the bands.

From time to time the sync would seem to go out of drift but was corrected with the other projects, I was able to correct that, but in this case, it doesn't look like it's something easy to correct. I wondered if I could mix sample rates and just import the file as a 44.1k rate and drop it on the timeline to compare it, but that doesn't work. All audio sample rates must match in the media 100 timeline, it's probably because the playback module has less effort in playing back one sample rate for all audio channels. Imagine the horsepower requirements to play and transcode everything to some common rate for playback in realtime.

To see if I can get a different length at the 48k rate, I imported the 44.1k audio at 44.1k and exported that audio as a 48k export, to be reimported into Media 100. If the transcoding is doing some kind of straight move from one bit by bit audio sample and just repacking the bits without doing a time calculation, kind of like an audio fit to fill, then the transcoded long sections will actually play back at a different rate. Which means the audio would drift out of sync.

I can do a playback and resample into another recorder using an analog mixing method to get rid of that problem if it becomes a problem.

I'm wondering if under default processing I've been getting this error and somehow my editing, with perhaps more cutting and moving around of smaller video clips masked that problem.

In any event, this is more of a diary update for future reference than a report of much progress. It's time to start editing again, been to busy with astronomy and various health issues around the house since the holidays.

I can say it was really run to watch some of The Choir again and relive the Cornerstone 2012 experience, without the 100 degree heat.

- Posted using BlogPress from my iPad

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