The audio quality control report from an international client contained an unusual request: the waveform of the dubbed track had to match the original. The dub was in sync and had already been approved in the studio. The client, however, overlaid the two tracks and wanted the start and end of every line aligned with the original, even where the ear would barely catch a difference.
The RED team re-edited the lines using the original waveform as a reference, and the redelivery was accepted. Since that project, waveform comparison has been part of our checks whenever a client requires it.
Every audio package goes through a technical check against the client’s delivery specifications before it ships. In a well-organized studio, that check closes a process set up from the moment the material arrives, which avoids second and third rounds of work.
Why a master can be sent back by audio quality control
Reports from platforms and distributors flag the file, the timecode and the issue. When the studio work is set up properly, the causes of a rejection come down to a few cases:
- Client-specific requirements. Checks that go beyond the general spec, such as waveform comparison, to be clarified before work starts.
- Picture changes after work has begun. If the final cut changes after the dub, every language version has to be reconformed to the new edit, otherwise the tracks drift.
- Different specs for the same title. Loudness range, true peak ceiling and channel order vary from one platform to the next. A master that passes for one client can be rejected by another.
- Frame rate conversions. When the picture for a given market is converted to a different frame rate, the audio for every language has to be conformed with the same method used for the image, so that sync holds.
In all of these cases, the decisive information sits upstream of the mix stage. That is why the checking starts long before the mix.
Audio quality control starts when the material arrives
Much of the checking happens at intake.
Before the first session we review the incoming M&E track, which has to be complete and free of leftover dialogue, along with the picture version, the running times and the latest delivery spec.
A flaw in the client-supplied M&E that surfaces at the end of the job means remixing every language. Caught on arrival, it takes a request for new material.
The same logic drives the mix, where tracks are organized with future versions already in mind, as covered in the article on what separates mixing from editing.
What a complete audio package contains
Audio deliverables for platforms follow a list that changes from client to client, built on a recurring core:
- the final mix in every required configuration;
- the M&E track, music and effects with no dialogue, complete and in sync with the final picture;
- optional tracks holding language-specific material, such as crowd walla or archival audio;
- separate audio stems for dialogue, music and effects, when required;
- the dubbed versions, in the same configurations as the original.
Netflix, for example, publishes dedicated guidelines for creating the M&E that call for a fully filled track aligned with the final picture master. It is the most delicate file in the package, because every future version is built on it.
Who signs off audio quality control before delivery
Final sign-off should rest with one person who knows the client’s spec and answers for it. At RED Audio Solutions, it is signed by whoever prepares the package, after a pass by the engineer who closed the mix. The checklist follows the project spec:
- full playback of every language version;
- running times and timecode compared against the final picture;
- configurations and channel order verified;
- loudness and peaks measured against the required values;
- any extra checks the client requires, such as waveform overlay.
In simultaneous release dubbing this step carries even more weight, because the margin between the last session and the go-live date is very thin. In our view, a rejected master always costs more than the check that would have prevented it.
Frequently asked questions
How long does audio quality control take for a series?
It depends on the number of languages and configurations, because full playback has to be repeated for every version. It is best treated as a separate phase in the schedule, ahead of delivery.
What are delivery specifications?
The document in which a platform or distributor sets formats, channels, levels, file naming and package structure. They change from one client to another and should be requested before the final mix.
What is the difference between an M&E track and audio stems?
An M&E track is a music and effects mix with no dialogue, ready for dubbing. Audio stems are the individual sound families exported separately. Platforms may ask for both.
Bring the spec to the studio from day one
Final checks run faster when the spec reaches the studio together with the material. Tracks, configurations and special checks are then set up from the start, and the final audio QC becomes a confirmation. For an international release, independent ones included, a conversation with the studio at the quoting stage helps align specs, review times and responsibility for delivery.
