In this episode you'll learn about audio formats.
Audio formats are the different types of files
that store audio on your computer, or your device.
A WAV is a type of audio format.
Let's explore the more common types of audio formats
that are generally used.
This week let's look at the very scary area
of sound production audio formats.
I say scary because there's so many types
and versions of the audio format.
I want to boil them down to the professional formats,
and then the root versions of many,
that you'll see in the digital domain like the Internet.
Let's start with the professional formats.
They are used all the time in
professional audio production.
Ladies and gentlemen first up the WAV.
WAV stands for waveform audio file.
Yes, that old favourite has won the battle for dominance
of the professional audio post world.
Most people will know it from the PC
that's sitting in front of them.
Two things to look at when looking at WAVs,
the sample rate and the bit rate.
The sample rate is the amount of
audio samples per second of audio.
So, which in the case of HDTV is 48 kilohertz.
So there are 48 thousand samples of the sound
playing in one second.
The bit rate is how many bits are in each sample.
To try and make this clearer,
and give you something for comparison,
consider a CD that was 44.1 kHz 16 bits
HDTV as I said is playing at a 48k, but at 24-bit.
The bit rate determines the dynamic range
of the audio file.
So 16-bit is around -96DBFS,
decibels relative to full scale,
24 bit is a lot more, it's around -144DBFS
and then 32 bit flow goes right up to -758 DBFS.
absolutely incredible.
AIFF is born in the same genesis as the WAV,
but native to MAC computers.
It works off the same principles of
sample rate and bit rate.
AIFF stands for audio interchange file format.
It was used all the time,
in any sound production in MAC land.
Then broadcasters around the world started to
adopt the broadcast WAV as the preferred delivery,
because it delivered multi-channel files,
and lots of metadata or text wrapped up in the file.
The AIFF started to be seen less and less
in post-production circles.
Suddenly in the 1990s things started to change with this
new technology that came around called the Internet.
Things were fairly slow and we did not have the luxury
of being able to shift large amounts of data around.
There had to be a solution to be able to deliver audio
over these thin band networks.
Along Came the MP3,
a format that allowed huge compression,
and leaving the file size small,
allowing the movement and listening of audio
over the earlier Internet.
I know they can sound truly awful,
but you have to take your hat off to the technology.
With the further development of the MP3 to AAC,
and the development of the MP4,
there was a vast improvement in the quality of the audio
but this is where the scary bit comes in.
MP4 is a container that can hold all types of media
like video and audio.
These MP4 files that contain video will have an
extension of M4V and an MP4 that contains only audio,
will have an extension of M4A.
Then to confuse the situation further,
there are lots container formats like Windows Media
which contain WMV and WMA.
Then there are others where the container
is less well known than the media within.
Such as OOG container,
whose audio media is called FLAC.
And then to add even more to the mix,
there's a whole new set of numbers to worry about,
like 192 KBS or 320 kilobytes per second,
which refers to the sample rate and the quality of the file
Don't worry about these right now,
if you have to work with these formats,
then 192 should be your starting point.
I don't want you getting totally freaked out
by these formats.
I just want to demystify all the scary fog.
Unless you're dealing with big internet stuff and video,
keep it simple stick to the WAV,
because everyone can handle it,
with broadband moving files around are simple.
the simplest way to reduce confusion or stress,
is to talk to the people that you're working with.
They will know what works for them
and you can suit yourself to their way of working,
making the workflow as easy as possible,
helping everyone and helping the whole project.
Just before I go there is one format,
that you may have heard of in professional circles
and that's the OMF,
or the later version the AAF.
OMF is open media format,
the AAF is advanced authoring format
this is a way of delivering an audio session timeline
from one person to another.
It was developed by the people,
who brought you Pro Tools,
but there are a lot of DAWs that can handle it.
When you finish your track lay,
or recording your music track,
you can export your timeline as an OMF or AAF.
I will suggest AAF if you can,
as it can support things like,
exporting your volume changes and other stuff.
Try to export into one file,
as it forces all the media into that file,
even if your audio is spread over several drives.
The other thing to do is to make sure you give it
generous handles of about 5 seconds,
or 5000 milliseconds.
It'll really help the sound editor out,
in a whole load of ways.
I want to let you into a little secret.
The AAF is not totally foolproof
I've received hundreds of AAFs,
that Pro Tools just can't open.
When under pressure to deliver a final
master this is the last thing you need.
I have found myself on many occasions
being able to open the AAFs that Pro Tools can't,
in another DAW or digital audio workstation,
called Nuendo.
I then export the timeline out from Nuendo
as a fresh AAF and then Pro Tools can read that export.
I've no idea why but the AAF handling in Nuendo
seems to be very, very robust.
Try it out for yourself,
it could save you a lot of time, energy
and a huge amount of frustration.
I'm Keith Alexander,
and you've been watching Adorama TV.
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