Missing Quick Time audio ? solved!

For months many FCP users including myself have been plagued with ?missing audio? when rendering quicktime movies from FCP sequences. I personally can?t begin to list the number of wasted productivity hours I have racked up re-exporting or fixing a faulty client viewing tape, OMF tracker or the likes. After some experimentation. I have finally figured out that the bug lies in the way FCP keeps track of renders and particularly RE-renders of audio. When I first posted my problem, a number of forum users suggested that there was ?no bug? and that one only needed to ?RENDER all audio? prior to any exports to avoid the problem. I did this before each QT export and still randomly had missing audio on my exports. These sequences were part of a long form project that had received numerous revisions. Those areas that were dropping out had been tweaked and re-tweaked again and again. It wasn?t until by chance that I stumbled on a solution to the problem. When working on a revision, one of the problem sequences required an overall level boost, so I executed a global audio adjust of a few db to the ENTIRE sequence audio, and re-rendered the audio. Voila? I exported a perfect QT movie. This global adjustment seems to fool FCP into thinking the sequence is a new sequence ready for a FULL re-render. I noticed a similar and possibly related bug in the FCP 3 and I believe 4 software, where after repeatedly massaging transitions on video tracks, the system would stop executing the changes. I would have to drop a bogus piece of video on the track above the problem transition, then delete it, and re-render ? thus fooling a FULL re-render. Note: This bug may also relate to the problem some users have been posting in the last month relating to missing audio when nesting?
So here is the work-around for at least the QT audio bug: Prior to exporting a QT movie, click in the sequence, go to the Edit pull down, Select All, go to the Modify pull down, click Levels, Relative, adjust + or ? 1 db, hit ok. Click in the sequence again and render audio (Ctrl,Optn,R), and then export QT movie. Hopefully Apple can make some improvements on there render software in FCP5.


MG

Or do a mixdown of the audio, which is what people have been saying all along. Mixdown your audio.

In HD you can find it in render > only > mixdown.
In previous systems Sequence > mixdown audio

Sorry - The key stroking is (Optn,Apple,R) and yes, it is technically a mixdown. But you need to do the global adjust of ALL the audio each time to avoid this bug.

MG

>>it is technically a mixdown<<

It *is* a mixdown.

The world is full of people who look a gift-horse in the mouth...

MG,
rather than adjusting the levels,
have you tried simply turning all your tracks OFF, then ON again?
the quick way would be to Option click on one green visiblilty button, solo-ing that track, (you will actualy get a "about to lose renders" warning) then click on that track again to turn it off.
OPtion Click one more time to turn all the tracks back on.

are you raising by 1db, then lowering by 1db?
otherwise, after doing this a few times, your levels could go thru the roof!

nick

Hi Nick,

Good idea on the track button...I'll try it. Yes to the 1 db + & - Q.

THX,

MG

MG - I'm not having a go at you - I'm saying that what you are doing is a mixdown. The concept of 'rendering ALL audio" is different to "mixing down" your audio.

In FCPHD the shortcut keystroke to do this is option-apple-R. When you have done this correctly, you can look in the menu render > only > mixdown and you will see that it is greyed out and there is a check mark next to it.

Unless there is something else wrong with your system you shouldn't need to force FCP to unrender everything first.

Can you explain the difference between "Rendering All" and an "Audio Mixdown"?

The mixdown function makes a single preview file of your whole timeline, which is used specifically for playback to reduce the pressure on the system and stop dropped frames and missing audio sections.

Rendering all audio renders all the files, but does not make them into a single file for preview, so the system still has to think about each one and its associated transitions and filters as it plays out, often resulting in dropped frames and glitches if the system can't keep up.

Actually ..

Here's a summary from the FCP help file


Using Mixdown Audio to Prevent Dropped Frames

If you have a complex audio mix with numerous clips, keyframes, filters, and transitions, it may start to affect the playback of your sequence.

Also, if the Audio Playback Quality setting in the General tab of the User Preferences window is set to High, you may get dropped frames in your audio.

You can use the Mixdown Audio command in the Sequence menu to render all of the audio tracks in a sequence, along with their accompanying transitions and filters, into a single render file.

Note: This command has no effect on how your clips are edited. All audio clips remain on their own tracks in the sequence just as they were before. The Mixdown Audio command only consolidates the clips for playback in an invisible preview file.

Once you?ve applied mixdown audio to a sequence, the menu item is dimmed and a checkmark appears next to it to show that the audio in the sequence has been rendered as a preview file.

If you move any audio clips afterward, the preview file is discarded, and the Mixdown Audio command again becomes available in the Sequence menu.

To mix down audio in a sequence:
1 Select a sequence in the Timeline.
2 With the Timeline or Canvas active, choose Sequence>Render>Mixdown Audio.



The last bit is actually wrong - in the latest versions you can only find the mixdown command under Render > Only > Mixdown.

bad thing about Mixdown:

it cant be batched, like other render functions.

so on a feature with 5,6,7 or more spools, or any project with multiple sequnces to output, someone has to sit there like a monkey, and do them all one at a time.

Feature Request!

nick

Sorry for the earlier typos. Here is the thread cleaned-up and clarified.

For months many FCP users including myself have been plagued with ?missing audio? when exporting QuickTime movies from FCP sequences. I personally can?t begin to list the number of wasted productivity hours I have racked up re-exporting or fixing a faulty client viewing tape, OMF tracker or the likes. After some experimentation. I have finally figured out that the bug lies in the way FCP keeps track of mixdowns and particularly RE-mixdowns of audio. When I first posted my problem, a number of forum users suggested that there was ?no bug? and that one only needed to ?MIXDOWN ALL AUDIO? prior to any exports to avoid the problem. I have always done this before each QT export and still randomly have had missing audio on certain exports. These problem sequences were usually part of long form projects that had received numerous revisions - those areas that were dropping out had been tweaked and re-tweaked again and again. It wasn?t until by chance that I stumbled on a solution to the problem. When working on a revision, one of the problem sequences (one that continuously exported to QT with missing audio) required an overall level boost, so I executed a global audio adjust of a few db to the ENTIRE sequence audio, and did a mixdown of the audio. Voila?I exported the QT movie for the first time with perfect audio. This global level adjustment seemed to force FCP into dumping the incomplete or corrupt mixdown files, and to replace them with a full clean mixdown. I noticed a similar and possibly related bug in the FCP 3 and I believe 4 software, where after repeatedly massaging transitions on video tracks, the system would stop executing the changes. I would have to drop a bogus piece of video on the track above the problem transition, then delete it, and re-render ? thus fooling a FULL re-render. Note: This bug may also somehow relate to the problem some users have been posting in the last month relating to missing audio when nesting? So here is the work-around for at least the QT audio bug: Prior to exporting a QT movie, click in the sequence, go to the Edit pull down, Select All, go to the Modify pull down, click Levels, Relative, adjust + or ? 1 db, hit ok. (note: keep track and alternate the + or - 1 db change over successive exports so as not to radically effect the overall levels of the sequence) Click in the sequence again and mix down the audio (Optn,Apple,R), and then export the QT movie.

FCP 4.1.1 Dual 867 mhz, 2 gig RAM, QT 6.5, OSX 10.2.8

MG

THANK YOU! THANK YOU! I Always mixdown my Audio and recently have been been the victim of the missing audio, and I can tell you, a simple mix down does NOT fix the issue.