Linear PCM Settings

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Level 1

8 points

Linear PCM Settings

I've looked around but I haven't found a simple, non-techy, clear explanation of the settings in the Quicktime Linear PCM audio settings. When should/shouldn't I use Little Endian, Floating Point, and Unsigned. What do they do? Thanks for your help.

MacBook Pro 2.4GHz, Mac OS X (10.4.11), QT 7.4.1

Posted on Mar 24, 2008 3:45 PM

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Answer 1

Mar 25, 2008 6:24 AM in response to Stacy K

All of those options would first be answered by knowing where your final file would be used.
How do you want to use your QuickTime file?
Send it to another video editing app? A Web page? An audio editing app?

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Answer 2

Stacy K Author

Level 1

8 points

Mar 25, 2008 3:21 PM in response to QuickTimeKirk

The QuickTime movies I create & convert are used for various purposes. They may be going to a client to preview the work or they may be the final product. I also create QTs that go to sound department people for video reference & temp/scratch sound. Every once in a while the QTs are for websites. So in answer to your question lets just say all of the above & more. I want to understand what these settings are for, when these settings are useful & when they should be avoided. Thanks in advance for your help.

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Answer 3

Mar 26, 2008 5:13 AM in response to Stacy K

Audio file or audio track using Linear PCM settings would only show the options above if it had been made above a 16 bit sample size.
CD audio (AIFF) is 16 bit at 44.1kHz, stereo and about 10 MB's per minute. Most average users think this is the "best" audio can be. You wouldn't use it on a Web page (too large) or even in a QuickTime file for "local" playback because of the file size.
DV Stream typically uses 16 bit at 48kHz (some use 32). This is what's made by most consumer level video cameras. These files are 13GB's per hour so they would also not be used for local or Web based files. They would be used between video editing apps to insure highest quality.
Endian is the byte order. Mac's use "big" and PC's use "little". Its name comes from some lines from Gulliver's Travels (big or little end of a soft boiled egg).
QuickTime supports up to 192kHz audio (4 times that of audio CD) and sample size rates of 8, 12, 16 and 32-bit integer & floating point, and 64-bit floating point. Those larger than 16 would be made by "high end" audio apps.
Since you get no value from "up-sampling" (16 to 32 bit) you wouldn't use integer or floating point unless your audio source started with them.
Hope this helps.

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