What info transfers with AAF files?

H2000 wrote on 4/22/2005, 2:14 PM

I am an audio only guy, but I figured I would ask here because you all seem to know more about this than anyone in the Audio Forum:-)

What kind of information if translated in the AAF file import and export? Volume, crossfades, envelopes, plugins? And, assuming a transfer between say Vegas and ProTools (Avid), would the media ineed to be BWF or can it be standard WAV format?

And, if it does need to be in BWF format, then is Vegas limited to import only? TIA

Comments

thankins wrote on 4/22/2005, 3:29 PM

H2000,

Here's some info that you may find helpful. These are notes from our AAF developer.

AAF Export
Usage: From the main menu of Vegas 6.0, choose File, Save As, then choose “Edit Protocol Compliant AAF File (*.aaf)” or “Avid Legacy AAF File (*.aaf)” for “Save as type” to save a project as AAF file. In the case where you have WAV encoded BWF files on the timeline (as opposed to MEPG encoded BWFs) you could choose "Edit Protocol Compliant AAF" and then check the option to Embed Media on the File->Save As dialog.

Video/Audio Cuts: Supported.

Effect: Video stretch is exported as AAF’s “Video Speed Control” effect.
Audio stretch is not supported because there’s no corresponding effect defined in the AAF SDK. Note: If a stretched audio clip has a PlayRate/Speed faster than 1.0, then the clip is converted to a non-stretched audio clip, and trimmed to match the original stretch duration. If a stretched audio clip has a PlayRate/Speed slower than 1.0, then the clip is converted to a non-stretched audio clip, with looping added to match the original stretch duration. Other Video/Audio Effects are ignored.

Transition:
Any Video transition (including Cross Fade) is exported as AAF’s “Video Dissolve”. Any Audio transition (including Cross Fade) is exported as AAF’s “Mono Audio Dissolve”.

Embedding AIFC/WAVE Audio: "Edit Protocol Compliant AAF" files may contain embedded AIFC or WAVE encoded data. (This includes BWF). Embedding media is accomplished by checking the associated checkbox on the File-Save As dialog. When you have audio media that’s not in AIFC or WAVE codec, the audio will not be embedded in the AAF file.

Additional Notes:
1. Tracks which have both mono and stereo audio are ignored during export because the AAF specification does not allow mono and stereo audio to be put in the same track.
2. For still image media in Vegas, the length is 0 and FrameRate is 0.0, which is not allowed in AAF. AAF requires the length of media larger or equal to the length of clips using that media. Thus, when we export still image media to AAF, we set its length to be a large constant value – 1080000 frames.
3. When exporting Vegas projects with offline media to AAF, because we cannot determine detailed info about the offline media, we set the length of the offline media to be a large constant value – 1080000 frames, and if the media is audio, we set it to be stereo.

Log file:
After an AAF export, a log file with name of $AAF_FILENAME.export.log is created in the same directory as the AAF file, where $AAF_FILENAME is the name of the AAF file (including .aaf extension).

AAF Import
Usage:
There are two ways to import AAF file(s).
1. From the main menu of Vegas 6.0, choose File, Open, then choose an AAF file to be imported. This would import the AAF file into a new Untitled project.
2. From the main menu of Vegas 6.0, choose File, Import, AAF, then choose the AAF file(s) to be imported. This would import the AAF file(s) into the current project.

Note: The file name of the AAF file(s) to be imported need to have the “.aaf” extension, otherwise they will not be recognized as AAF files.

Video/Audio Cuts: Supported.

Effect:
Only AAF’s “Video Speed Control” effect is imported. Other Video/Audio Effects are ignored.

Transition:
Any Video/Audio transition is imported as a Cross Fade in Vegas.

Extracting Embedded AIFC/WAVE Audio
If there is audio media in AIFC or WAVE codec embedded in the AAF file, it would be extracted to $AAF_NAME.extracted.%d.%s.aif or $AAF_NAME.extracted.%d.%s.wav, where $AAF_NAME is the AAF file name, and %d is the number of extracted files so far, and %s is the name of the embedded audio (which could be empty). If the embedded audio in the AAF file is not in AIFC or WAVE codec, then the audio is not extracted.

Log file:
After an AAF import, a log file with name of $AAF_FILENAME.import.log is created in the same directory as the AAF file, where $AAF_FILENAME is the name of the AAF file (including .aaf extension).

-Tim.

H2000 wrote on 4/22/2005, 4:12 PM

Thanks Tim! That's great information.

One thing that I see that would be a problem is that ProTools (with Digitranslator2) does not import embeddded AAF files. It only imports referrend AAF. And, in the case of media it would refer to, it would accept BWF of AIFF. But, from the looks of it V6 doesn't write BWF files. Is this correct?

I supposed one could convert all wav files to aiff for the project and then replace all project files with aiff files, but it seems a long way to go about it for something that's supposed to make things easier.

Or, perhaps normal MS wav files will import anyway even though they are not BWF. Does anyone know? Has it been tested?

newhope wrote on 4/23/2005, 6:00 AM

ProTools will import and convert normal wav files to whatever the audio file format you have set your session to work with. BWF, AIFF etc. It usually doesn't use the BWF suffix anyway even when the session is set up in BWF format. It will default to using WAV as the suffix for BWF files. You may be able to set up the session to use the BWF suffix in ProTools, I can't say I've tried it but I work on ProTools HD systems that generically are set to work in BWF with the WAV suffix and we receive OMF files that are normally in AIFF. ProTools converts them during import. I haven't used AAF much but I assume it would do the same.

Steve

H2000 wrote on 4/23/2005, 8:45 AM

Thanks Steve! That's the answer I was looking for!