Archive for February, 2016

Use Avid’s Group by Waveform Function for AutoSync

Monday, February 1st, 2016

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Media Composer 8.5 brings lots of new functionality, one of which has been a long time request of using audio track analysis to sync clips. This functionality has been available in other NLE’s for some time and was available to Media Composer users via PluralEyes. PluralEyes still has advantages over what is currently offered in Media Composer, namely the ability to sync in batches. How to use PluralEyes for syncing dailies can be read in this previous blog.

Waveform syncing in its first release is reserved for grouping clips in preparation of multicamera editing. It is not yet available for syncing dailies in AutoSync or with the multigroup function. However, it does work quite well, but does have a few quirks to be aware of when using; It will always create a group clip whether the selected clips belong together or not. It will also create a group clip from a batch of TIFF files that have no audio. The user is warned that clips with no audio will be ignored, but you get a group clip anyway. The function depends on the user properly selecting the clips that belong together before using this feature.

But there is a workaorund to use this function to sync dailies when there is no other method to find proper sync. In my example, the footage does have slate and claps, but I am using it as an example as the source clip had scratch audio to match the double system BWF files. It is a multi-step workaround process, but can come in handy when there is no common timecode, slate, clap or otherwise. My example uses a clip from a feature film that was shot on the Canon 5D (no timecode) and an 8 track BWF recorder with TOD. The BWF files were imported into a 35mm 4 perf project so that I can still slip sync by quarter frame when needed as described here. The process starts by selecting the two clips you know belong together and selecting “group clips” from the Clip menu (no longer in the bin menu with 8.5).

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This will create a group clip. Load group clip into source monitor and Mark IN and OUT to active picture and sound (do not leave any Avid black).

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The resulting timeline with waveforms active will look like:

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For whatever reason, the better recorded tracks in this file were on tracks 5 & 6. Highlight the tracks you want to keep in the resulting .sync clip and contrain/drag to tracks 1,2, etc. (1&2 in this example):

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Back in the bin, highlight the sequence that was created and select “Commit Multicam Edits” by right-clicking the sequence. This is an important step otherwise the AutoSync function will not work.

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Highlight the new sequence that was created from the previous step, and select “AutoSync” from the Clip Menu.

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The result is a subclip that behaves like any other AutoSync clip with sync offset indicators, the ability to match back to original BWF files to grab ISO tracks, and track patching is indicated in the EDL. And since this was a 35mm 4 perf project, the ability to slip sync on quarter frame boundaries.

Keep in mind that scratch track audio in many cameras is not perfectly in sync to start with. See this blog.  Any resulting waveform syncing will be out of sync by the same amount. This can be handled as a post sync process as described with the quarter frame sync slip. It would be nice to see in any of these of waveform syncing applications the ability to add a +/- offset as part of the original clip metadata and be used as part of the sync process. For example in Media Composer, a column named “Sync Offset” (or other name) could have a value of +1 or -1 that represents scratch track audio being ahead or behind by 1 frame. User can enter whatever value and decimals would be a good thing too, even if it were to match Avid’s quarter frame support: +/- 1, 1.25, 1.5, 1.75, 2, 2.125, etc.

We’ll see how this new waveform function gets improved in future releases.