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U-Law compressed sound - best format when extract from .mov?

Started by Andrew Thompson December 17, 2005
I have some Quicktime MOV's that I recorded on my camera with
the lens cap on, purely for the sound.

Player software indicates the sound is recorded as U-Law,
16KHz, 8bit, mono.

I want to extract the sound to a separate (sound specific)
format for further editing, and am offered the choices (in
current software) of MP3, Wav, AIFF and AU.

The ideal is to get a sound-only rendition of the audio track
in as accurate a form as I can get it.  I figure if I can take it
to another sound format that uses U-law compression, and at the
same bit rate, it will be the best rendition of the audio track
that is available.

Is that assumption reasonable, or did I miss something important?

Since MP3 is a lossy format, I am avoiding that, and would
prefer not to use Wav because of it's close association with
Windows.

Do either of the formats AIFF or AU use U-law compression
(or can they)?

-- 
Andrew Thompson
physci, javasaver, 1point1c, lensescapes - athompson.info/andrew
Andrew Thompson wrote:
..
> I want to extract the sound to a separate (sound specific) > format for further editing, and am offered the choices (in > current software) of MP3, Wav, AIFF and AU.
..
> Since MP3 is a lossy format, ...
I am assuming here - lossy in a new and different way to a U-Law compressed sound, like converting a JPG image (one lossy pic. format) to ...GIF (an entirely different type of 'lossy' in that it has a limited palette).
>..I am avoiding that, and would > prefer not to use Wav because of it's close association with > Windows.
Uhhh. Further investigation shows AIFF is Mac. and AU is Sun/Unix. I cannot exclude them all, so.. OK - Wav is back in.
> Do either of the formats AIFF or AU use U-law compression > (or can they)?
Pay dirt. <http://www.nch.com.au/acm/formats.html> AU supports U-Law compression. <http://www.nch.com.au/acm/index.html> Wav supports U-Law compression. AIFF.. still not sure, but since I can use either AU or WAV, I think I'll use AU. [ Comments still very welcome. Especially if I misunderstood any of what I was reading. ] -- Andrew Thompson physci, javasaver, 1point1c, lensescapes - athompson.info/andrew
Andrew Thompson wrote:
> Since MP3 is a lossy format, I am avoiding that, and would > prefer not to use Wav because of it's close association with > Windows.
There's nothing wrong with .wav as a file format (it's a subset of RIFF) -- it's widely supported and it handles u-law encoding directly. You should get a bit-for-bit copy of the soundtrack. http://www.sonicspot.com/guide/wavefiles.html#fmt -- Dave Tweed
Andrew Thompson wrote:
> Andrew Thompson wrote: > .. > > I want to extract the sound to a separate (sound specific) > > format for further editing, and am offered the choices (in > > current software) of MP3, Wav, AIFF and AU. > ..
Linear PCM can be mapped directly from uLaw. Linear PCM is what most editor / manipulation programs will use. Rocky
David Tweed wrote:
> Andrew Thompson wrote: > >>Since MP3 is a lossy format, I am avoiding that, and would >>prefer not to use Wav because of it's close association with >>Windows. > > There's nothing wrong with .wav as a file format (it's a subset > of RIFF) -- it's widely supported
True. I ultimately want to pump parts* of the sounds out through the speakers or as soundbyte files to most of the common formats (including MP3) at the point of the end user, so as long as the format is not lossy and is readable by Java (which the software will be written in), it should be fine. And yes, Java can handle Wav (and AU - obviously) in the core API, but ultimately I will rely on the Java Media Framework to add support for other formats such as MP3. * They are long recordings of 'nature' with a lot of sounds of 'planes, trains and automobiles' (..bicycles and motorcycles, joggers... Aaargh!) in the background at points.
>..and it handles u-law encoding > directly. You should get a bit-for-bit copy of the soundtrack. > > http://www.sonicspot.com/guide/wavefiles.html#fmt
Thanks for the link - very comprehensive information. Just checked that a Wav/AU or roughly the same size. A 1.147 Meg AU does translate to the same size Wav (well, to within 32 bytes, probably because of differences in the header). I think I'll stick with AU, but my knowledge/understanding of sound formats is now much more solid. -- Andrew Thompson physci, javasaver, 1point1c, lensescapes - athompson.info/andrew
Rocky wrote:

> Andrew Thompson wrote: > >>Andrew Thompson wrote: >>.. >> >>>I want to extract the sound to a separate (sound specific) >>>format for further editing, and am offered the choices (in >>>current software) of MP3, Wav, AIFF and AU. >>.. > > Linear PCM can be mapped directly from uLaw. Linear PCM is what most > editor / manipulation programs will use.
..hmmm. I take it Linear PCM is used because it is most 'robust' to further editing/mixing? I will have to investigate that further, it might be better to transform the sound directly to Linear PCM if 'direct mapping' means a lossless/exact transition to a better format for editing. -- Andrew Thompson physci, javasaver, 1point1c, lensescapes - athompson.info/andrew
Andrew Thompson wrote:

   ...

> ..hmmm. I take it Linear PCM is used because it is most > 'robust' to further editing/mixing? > > I will have to investigate that further, it might be better > to transform the sound directly to Linear PCM if 'direct > mapping' means a lossless/exact transition to a better > format for editing.
The coding doesn't matter, but the linearity does. Mu-law is a piecewise-linear approximation to pseudo-logarithmic (negative numbers accommodated) encoding. Signals in that form can't be mixed, properly adjusted for volume, or analyzed for frequency content. Jerry -- Engineering is the art of making what you want from things you can get. &#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;