Footage from an Avid drive

Avid keeps a shot's picture and each channel of its sound in separate files. Point A/Side at the drive and they come back as one clip, with the sound on it.

Point A/Side at a drive with Avid MediaFiles on it and you get clips, with their sound. There is nothing to set.

That sentence is short and the work behind it is not, because of how Avid stores media: one picture or one channel of sound per file. A shot with four tracks of production sound is five files on the drive, and nothing in their names reliably says they belong together.

What it does

A/Side reads the header of each file, which carries the identity of the clip it came from, and puts the clip back together: the picture, and each channel of sound in order. One row in the bin, with four channels on it, exactly as it was shot.

Without this you would get what the files literally are — a silent shot and four separate mono clips — which on an episode of drama is thousands of rows nobody wants and a cut that plays silent.

What it tells you, and why

Three things get said out loud rather than quietly handled, because each of them is a thing you might want to check against Avid:

"the channels are in filename order." The order of a clip's sound normally comes from the file headers. Some media does not carry that, and then A/Side falls back to the filenames — which is almost always right and occasionally not. It is the one thing about a clip you cannot check by looking at it: a picture in the wrong place is obvious, two tracks of sound swapped are not. If you see this, solo the tracks on one clip and compare.

"the files of this clip are not all the same length." Avid's sound files are often a frame or two longer or shorter than the picture. Nothing is trimmed to make them agree, because which one is right depends on the clip — you are told the range in frames and left to decide.

"duplicate copies … folded." Avid MediaFiles/MXF/1 and /2 routinely hold the same file after a consolidate or a copy between drives. Those are counted once. Two files with the same name and different sizes are not duplicates — they are two renditions of the same material — so both are kept and mentioned.

Graphics and their mattes

Media Composer keeps an imported graphic — a lower third, a logo — as two picture files of one clip: the fill, and its matte (the alpha) in a file of its own. B/side makes that one clip: the graphic, keyed, in the monitors and in the export, with nothing to set up.

Which file is which is read from the files: the matte is the picture with no colour in it, or, when both are in colour, the one Avid named second (…V02 beside …V01). When nothing says which is which, the clip says so rather than guessing — a guess would key a graphic against its own picture.

Avid keeps mattes white-is-clear, the opposite of nearly everything else, which is why its import inverts a file's alpha by default. B/side turns Avid's matte over when it draws it, so a graphic that looked right in Avid looks right here. If one shows as its own silhouette instead, it was imported into Avid with "Use existing" and stored the other way: right-click the clip ▸ Colour, Crop & Rotate… ▸ Matte: Straight. Nothing is re-made; it changes in the monitors at once.

When the graphic's original file is still on a drive — the PNG or the ProRes 4444 — B/side reads its own alpha directly and none of this applies. An export from the cloud copy of an Avid graphic keys it from the proxy's matte and says so.

Clips with no sound

A file whose header carries no clip identity is brought in on its own, and A/Side says so: a picture that could not be paired will be silent. It is never attached to a clip on a guess. Sound laid against the wrong picture is a mistake that survives into a cut and is found at the mix, which is far worse than a shot you can see is missing its sound.

This is editorial media, not the camera original

On a scripted show the dailies house holds the camera negative and the cutting room is given media to cut with — historically DNxHD 36. B/side records that difference rather than treating the originals as missing: nothing is reported as lost, and the master is conformed from the originals by whoever holds them, from the cut you send out. See what can be finished.