Re: [ARSCLIST] BWF RF64

[Eric Jacobs <EricJ@xxxxxxxxxxxxxxxxxxx>]

Konrad,

Thank you for this very informative response.  A few more questions:

1.  Do you keep or discard the single RF64 file after you've
    split it and generated the multiple BWF files?  I suppose
    one's choice has as much to do with the cost of storage
    versus the cost to recreate the merged audio again later.
    I'm guessing that because of the minimal technical differences
    between RF64 and BWF, they will be equally easy/difficult
    to migrate in the future, and that migration is a non-issue
    when choosing to discard or retain the RF64.

2.  If you generate access formats (like MP3), do you generate a
    single MP3 from the RF64, or multiple MP3s from the split
    BWFs?

    I think a single MP3 offers a better user/access experience
    because of the lack of interruptions, but multiple MP3s are
    perhaps easier to manage from a data point of view because
    of their one-to-one correspondence with the BWF preservation
    masters.  Naturally, MP3s are not "preservation" files, so
    I might bias my choices towards the user/access experience
    (ie. a single MP3).


Eric Jacobs

The Audio Archive, Inc.
tel: 408.221.2128
fax: 408.549.9867
mailto:EricJ@xxxxxxxxxxxxxxxxxxx


-----Original Message-----
From: Association for Recorded Sound Discussion List
[mailto:ARSCLIST@xxxxxxx]On Behalf Of Konrad Strauss
Sent: Tuesday, September 04, 2007 7:28 PM
To: ARSCLIST@xxxxxxxxxxxx
Subject: Re: [ARSCLIST] BWF RF64


on 9/4/07 5:07 PM, Eric Jacobs at EricJ@xxxxxxxxxxxxxxxxxxx wrote:

> Is anyone using BWF RF64 (RIFF 64 chunk) for large archival BWF files
> (larger than 4GB)?

We have done quite a bit of experimentation with file sizes and formats for
our live recording archives (click on the Blog link below for some entries
about what we're doing.)

Basically, there are major compatibility problems with any files larger than
2 GB. Pro Tools, for example, will not recognize a file over 2 GB.
Cuebase/Nuendo and Adobe Audition will happily record and play back 4 GB
files, and the resulting files will open and play in Wavelab. However if a
BWF file recorded in Wavelab exceeds 2 GB it will be corrupted - I forget
the exact behavior, but I think only part of it was playable.

When we did our tests, about a year ago, RF64 was supported only by Wavelab,
Cubase, Nuendo, and Pro Tools would not recognize the file as audio. We did
not test Adobe Audition and Soundforge. This may have changed since then.

So, to ensure compatibility we keep all files under 2 GB - about an hour of
recording time at 96/24 stereo interleaved. Generally this is no problem
(the split button in the Wavelab record window makes it pretty simple to do
on the fly.) Occasionally though, files end up being larger than 2 GB.
Operas for example can be difficult to split live, so we have the RF64
option checked in Wavelab's record settings to allow longer recordings. If
the live recording exceeds 2 GB, we split the files into < 2 GB chunks after
the recording is completed.

Our files are distributed to a number of destinations and so far there have
been no compatibility problems. We will probably reassess our procedures in
the near future, but until we see near-universal support for RF64, we will
continue to create < 2GB BWF files.

--
Konrad Strauss
Director of Recording Arts, Professor of Music
Indiana University Jacobs School of Music
http://php.indiana.edu/~kstrauss
http://www.music.indiana.edu/department/audio/
Blog ­ http://munson.music.indiana.edu/audioblog/
Podcast ­ http://www.music.indiana.edu/iumusiclive/authorize/podcasts.shtml