Re: [Dev-C++] New to the list, and a quick question

[Per W. <pw...@ia...>]

Note that non-lossy audio compression (I'm definitely not talking about
zip :) or similar) have a hard time giving more than 30-50% compression
for music.

Software that needs to be delivered with audio samples often requires
non-lossy audio (instrument samplings for a sequencer software) or have
too small sample files for it to be worth it to bother with mp3 or similar
(informational/error sounds or speech messages).

Consider for example an application I developed at a previous employer. It
was delivered with alarm messages. Let's assume 50 different alarm
messages, each about 3 seconds long. 150 seconds times 22kHz 16-bit mono
is less than 7MB total size. The need for sound compression would in this
case be quite small, and I think this would be representable for quite a
large percentage of applications that are distributed with sound data.

The other end of the spectrum is of course high-end sequencer software,
that might be delivered with many GB of sound samples, but then the
requirements are often 24-bit non-lossy audio.

While multimedia players make good use of (lossy) compressed audio, I
really don't think they are representative of software that are
distributed with audio. You get the player without any sound clips, and
you then collect your music separately.

/Per W

On Thu, 11 Jan 2007, Roger Furer wrote:

> Aloha from honolulu,
>     If you use a .wav file this is usually uncompressed audio.  There
> are several compressed audio formats .mp3, .m4a, etc.  Microsoft and
> Apple each have their own formats that Windows Media Player and iTunes
> use.  I'm not sure about Unix/Linux, but the point is audio compression
> formats exist and deliver reasonable results.  Don't try to compress a
> .wav file into a .zip and expect to enjoy the listening experience.
> (Although that isn't based on my experience--I've never tried it.)
>     In professional recording the trend now is to record the tracks at
> the higest resolution, now 24-bit/196KHz sample rate.  Then mix to
> stereo file (at same res) then downsample to meet spec for various
> formats.  Audio DVDs are 24-bit/96KHz and CDs are 16-bit/44.1KHz.  Audio
> for video is usually 16-bit/48KHz.  Note that none of this is
> compressed, it is just using less of the original information.
>     MP3 (MPEG-1 Audio Layer 3) on the other hand is defined as a lossy
> compression format where "inaudible" data is removed from the audio
> file.  Look up "MP3" in Wikipedia http://en.wikipedia.org/wiki/MP3 the
> article has information on the various formats in use today.
>     The compression ratios are quite impressive, but you must choose
> what type of compression you use, based on the audio material involved.
>   Speech can be compressed the most.  Loud, hard rock and roll music can
> handle a lot of compression.  Delicate classical music with large
> dynamic range will suffer the most from compression.  If you have the
> time and tools, run the audio through an oscilloscope and compare
> uncompressed to compressed.
>     Hope this is helpful.
> Aloha,
> Roger Furer
>
> Per Westermark wrote:
>
> > Note that sound is very hard to compress, and for most applications it
> > isn't meaningful to spend any time to compress/decompress it.
> >
> > The only situations where compression is important is when used in flash
> > memory of small hand-held devices, or if transmitted over a
> > bandwidth-limited media, such as using a GPRS phone.
> >
> > Cmpiling audio or images into an application is quite often done, and
> > works very well. By having the information in the exe file - or even
> > better in one or more dll files - the OS will be able to throw away the
> > information in case of a mermory contention. If the information is read in
> > from a data file (read in, instead of memory-mapped), the OS must swap out
> > the information so that it can restore the information later without
> > letting the application know about it. Information stored in resource
> > files, the exe file or a dll file does not need to be swapped, since the
> > OS specifically knows how to load the information on demand directly
> > from the original source.
> >
> > /Per W
> >
> > On Thu, 11 Jan 2007, Pedro Perez wrote:
> >
> >
> >>Hello;
> >>
> >>   Is not advisable to include a complete audio file in your program, maybe if is a small file you can include it as a resource file.
> >>
> >>   I think the best you can do  is to pack it in a file in some format you desire (*.dat), unpack it and use it as desire. (Tip: You can apply a compress format leaving the .dat extension and then encrypt it, that helps too).
> >>
> >>
> >>
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