Audio FAQs

FAQ for Audio Post Production QC

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Q: My movie was rejected in QC for mono audio, even though I know the movie is in stereo what do I do?

A: This is a common problem often found in quality control processes. Stereo audio fails as mono because the movie was output to a final self contained quicktime file incorrectly. During Final Cut Pro, or Adobe Premiere file export, audio being exported must be panned. These program’s audio mixers contain sliders / knobs that have to be set for stereo audio, they must be panned left for left channels & vice-versa for right channels. Additionally files containing more than 2 channels must have audio tracks output to the correct corresponding channels for export. Editing program default all outputs to Channels 1 & 2; additional tracks on exported files will not be found if not exported correctly. We offer audio & video fixing, conforming, and outputting, as part of our Finishing Services, and can help with any issues such as these that need to be corrected in order to pass QC

Q: What are the different sets of audio tracks that make up the audio configuration.

A: A project being submitted for Quality Control could have many different combinations of audio tracks. For movies the audio sets that may be included are Stereo Mix Left & Right, Stereo M&E Left & Right, and 5.1. (6 Channel Mix)
If only one set of these sets of tracks are on the tape / file (Stereo Mix or 5.1) that is considered a one pass QC. There may also be one or both of the other 2 sets of tracks making the QC either two pass or three. A “Pass” is watching the whole movie through for video and whichever set of audio tracks we are monitoring at the time. So a 3 pass QC will have the movie or show watched / gone over 3 separate times.

Q: What is an “M&E” track and what can cause it to be rejected

A. M&E refers to “Music & Effects,” in an M&E track all audio that is on the stereo mix track is present except dialogue. The reason or this is for the purpose of dubbing the movie or show into other languages. All other audio is present and the audio dubbing facility just has to add dialogue.
An M&E track is primarily rejected for “Missing effects in M&E” which means any sound effect that is present in the stereo mix track that is not also present in the M&E track. This could include footsteps, doors opening and closing, tapping on a desk, hand clapping or any type sound effect. All must be present in M&E tracks. We specialize in fixing missing effects in M&E, even without source files if we have to. You can learn more about our Audio fixing at our Audio QC & Post page.

Q: How is audio measured? what are the correct audio specs for a stereo or M&E mix?

A: Audio levels are measured using an audio meters and phase scopes. Levels are measured on a scale known as dbfs. The dbfs scale us measured as negative numbers with zero being the highest allowable levels in movies and film.
Audio begins to become audible at -90dbfs. The reference tone for audio levels in the United States is -20dbfs, this is the level that the tones in the bars & tones are at and is used to ensure that all audio is measured the same. At the reference level of -20dbfs tv or audio levels will be average for a normal conversation that you would hear on a show. Many Television networks limit audio to peaks at -12 or -10dbfs. For movies 0dbfs the spec. Any audio that goes above 0dbfs is considered “clipped” and will usually cause distortion. An Quality Control report will list the audio peaks and any instances where the peaks are clipped.

Q:Our film was rejected for excessive Loudness. What is the difference between Audio Loudness and Audio Peaks?

A: There are several measurements we take when doing the audio portion of a Film or TV QC Report.
“Loudness” refers to the overall average of the dialogue throughout the entire show. Metering loudness is a fairly recent addition to QC, measuring it came as a result of a law called the “Calm Act,” this was put in place to ensure audio levels were the same across all TV shows and commercials. Have you ever been watching a show, then a commercial comes on that is much louder than the movie? This is what the calm act tries to stop.
Audio Loudness differs from audio peaks which are the highest levels the audio gets to during the program. Loudness levels have mostly replaced audio averages on QC reports as they are more specific and measured differently. Under the Calm Act Loudness reading should be between -22 & -26 LKFS (or LUFS) these levels are measured using specific programs used to measure loudness such as Adobe audition or The Dolby LM-100 Loudness meter. The entire show must be scanned to get an accurate reading. If a show or movie as Loudness levels that are too high or low they must be adjusted to spec. When fixing these issues, Loudness and audio peaks work in tandem with each other as 1LKFS = 1LUFS = 1dbfs. Fixing the loudness issue involves raising or lowering the overall audio levels to within the audio specs, while still keeping the audio peaks in spec.

Q: My movie was rejected for “Missing Effects in M&E” What does this mean

A: The M&E track should contain all audio that is in the stereo mix track except English (or whatever language the movie is in) dialogue. M&E tracks need to be “fully filled” in order to be approved. Often the M&E track will not contain effects that are in the stereo M&E track. These all need to be present. Many times the problem arises because the effects that come through the microphone that is recording dialogue while shooting are used in the final mix, and if a character is talking during an effect it cannot be used M&E. This is often a problem for low budget movies. In big studio movies All effects are created in a Foley studio, and dialogue from shooting is replaced in post-production.

Q: What are the specific things that should be in an M&E mix and what should be left out.

A: We have compiled a page that gives you the exact specifications for an M&E mix as part of the industry standard. Some distributors will have different requirements and you should check with them. Here is a standard list of specific M&E requirements.
Audio Specifications for an M&E (Music & Effects) Track for Film & TV

Q: What are the correct “specs” for a 5.1 mix.

A: Officially there are no written specs for a 5.1 mix per say; unlike other video and audio specs that have been defined over the years by SMPTE. (The Society of Motion Picture and Television Engineers) But all the large studios produce 5.1 mixes in the same way: The first two tracks of the mix are called Left / Right. These should be the same as an M&E track (music and effects only) The third track is called “Center” which should be dialogue only. The Forth track is called LFE or “Low Frequency Effects” This should be only deep bass sounds which would normally come from a subwoofer. Both the Center and LFE tracks must be mono as they are one track each. The fifth and sixth tracks are called “Left Surround / Right Surround” which is basically a match of the Left / Right tracks but at a lower level.
Mistakes on a 5.1 track that we often find (and may be approved by distributor or network) include.
1. Dialogue on any track other then “Center” which is the only place it should be
2. Music and / or effects in “Center” track which should be dialogue only
3. LFE track not containing Low Frequency effects only, or LFE missing completely.
4. Left / Right and or Left Surround / Right Surround tracks not being in stereo.

We can work with you to get your 5.1 mix correct.

Q: Our Deliverables lists includes 5.1 M&E Mix, and Audio Stems. Is this part of The QC?

A: In most cases the 5.1 M&E mix is not included in The QC report, although in some instances it is required, which would make the self-contained quicktime file to be QC’d a 16 channel file instead of the usual 10; it also adds an additional pass to the Quality Control Process. Audio Stems which are separate “D,M,E” files are individual audio tracks (.Aiff, or .wav) that contain dialogue, music, & effects. These files can be used to re-mix the audio of the movie. These are delivered separately from the final Quicktime file that is the movie.

Q: Our Audio mix was flagged for ADR issues, specifically loose ADR, what does this mean.

A: ADR stands for Audio Dialogue Replacement. Often when movies are made, the dialogue that is recorded through the boom mics is less than ideal for the final mix. The films producers will use ADR or “looping” to improve the sound of the dialogue in post. You have probably seen movies where actors have to go to a studio, watch the movie and say the lines into a microphone as they are being said in the original daily shoot footage. Once all the dialogue has been re-recoreded it is “replaced” back into the sound mix of the movie. Problems can arise when the sound sync and between the original dialouge and the ADR dialogue don’t match. On some occasions the dialogue can go in and out of sync during a single sentence, this may occur of the original footage was transferred to a different timecode. Loose ADR can be fixed either by adjusting the sync for full scenes or the entire mix, or by painstakingly editing every line of dialogue where they sync issues occur.

Q: OK we are ready to send your are project for QC, What exactly do we need to send.

A: Glad you asked We have a page that answers that very question in fine detail it’s called What You Need To Send Us For Film QC Please refer to this sheet for how to proceed. Of course we are also available to answer any additional questions by phone or text anytime.

Please contact us for any other FAQ for Audio Post Production QC Questions.