                 ********************************************
                          Frequently Asked Questions
                        by several users, using FalcAMP.
                              updated: 20/04/2000
                 ********************************************


Q: The MP3 sound plays OK but there are some additional very weird sound
effects - like in an old 8-bit SpaceWar-like game. It's the same regardless
of operating system and graphics output/resolution. It does it on some Stereo
and Joint-Stereo MP3 files.

A: You probably heard at what we called the "bubble bug" (because it sounds like
a kind of electronic bubbles into the sound !). This was a bug into our layer
3 scalefactors decoding. Now, you should never have this bug anymore: we shot
it ! :-)

                              -------------------

Q: ...Perhaps it's a side-effect of the transformation from 44100 Hz to the
Falcon replay freq?

A: No. It is true that the order 0 interpolation we use for all Falcons without
external clock decreases slightly the sound quality (particularly in high
frequencies). So, you will not have real CD quality. But it will never adds
big noises into the sound !

                              -------------------

Q: Unfortunately FAMP is not fast enough on my falcon with Afterburner (040 processor
running at 32Mhz) to play MP3-files under TOS as well as under N.AES 2.0. What can I
do? I don't want to overclock my DSP chip so would an external clock help?

A: As surprising as it could be, your Afterburner board cannot really helps
FalcAMP, because it speed up only the 68xxx processor, not the DSP56001.
FalcAMP needs the power of both processors, so if only one of the two runs
faster, this will not resolve all your problems:
- If the 68xxx is faster, file parsing and Huffman's decoding will be done
easily. The result for you is that using FalcAMP under a multitasking
environmnent will be not a problem, whatever you do. So, you will improve
your COMFORT using FalcAMP, not the sound quality.
- If the DSP is faster, final layer 3 resolving will be easier so that
you can choose the maximum sound quality options... but on the 68030
side, you could have serious slow down of your system, especially under a
multitasking environment. So, you will improve the SOUND QUALITY, not your
comfort !

Yes, an external clock will help a lot your poor 32Mhz DSP ;-) because it
will have only 44100 samples to play per second without any interpolation
computations, instead of 49170 samples/sec with an interpolation. It will
decrease the DSP load about 6%, wich is very important because the DSP is
often just beyond 100% of its abilities. With external clock, it is often
just below 100 % ! 

                           -------------------

Q: I have a speeder in my Falcon called "PowerUp2". This accelerater clocks the
CPU with 32MHz, when the CPU doesn't access to the bus. But when running falcamp
there is no speed improvement with the accelerator switched on :(. Isn't the CPU
calculating, when the Shifter accesses to the RAM? Isn't then some CPU-time wasted?

A: If your CPU is overclocked, you must have speed improvement. Until v.0.82,
FalcAMP was designed for monotasking, so you cannot feel improvement. Now, as
FalcAMP is interrupt based, under a multitasking environment you can see that
there is a big difference between basic and powered Falcons !

                           -------------------

Q: When *.mp3 is in Directories on a CD Joliet format or more than 8+3 characters
format, FalcAMP wrote "PATH NOT FOUND".

A: FalcAMP is not responsible for this problem. It is a bad configuration of your
desktop. FalcAMP support longnames even those with spaces inside the name. For
examle, if you use Jinnee 2.01 and you want to install FalcAMP as an application
you have to remove default commandline (%$p) and just set it to open/show *.mp3
files. When you install it as an application under TOS, ask for the full path
of the parameter, not just the filename...This way, FalcAMP will always find the
files you want to play.
  After some checks, it seems only Magxdesk caused a real bug by sending
strange commandline (not using "ARGS=" in the environment string for sending
a file name with spaces). It used a kind of drag'n'drop form but not the
standard one. A workaround is now included for this...

                           -------------------

Q: I want your sourcecode ! When will it be available ?

A: As soon as Joint-Stereo will be finished, and that requantisation will be
coded in a more DSP friendly way. We strongly hope to let FalcAMP works on
basic Falcons before releasing them ! Anyway, we already gave parts of
our DSP code to the author of DelfMPEG (AMIGA's MPEG player for Delfina DSP
56002 boards). And we are proud to see that our work helped people to make
another layer 3 player. This is a great reward for our work.

                           -------------------

Q: Some people said that your player have a low sound quality, is that true ?

A: It is true that we cannot get the same accuracy than PCs or Macs
which use double precision numbers. The DSP use 24 bits fixed-point
numbers. It was not possible to use 48 bits fixed-point numbers because
of the required optimization of the player. 24 bit numbers could be
not wide enough to store some results without negligible error.
Most of the time this error is really weak compared to AMP's C result
(lower than 0.01%). It could seldom range between 0.1-0.5% of error.
So it is really hard to notice any difference (we compared WinAMP and
FalcAMP in realtime, and we were not able to say which played best).

Also, many people used old releases of FalcAMP which have a really low
computing accuracy. Furthermore, many people have not an external clock
on their Falcon and so, the music must be interpolated by FalcAMP. And
the used order 0 interpolation give relatively poor result compared to
a "clocked Falcon". Also, people forgot that Join-Stereo is not yet
supported. So, for Joint-stereo files, the sound of FalcAMP cannot be
compared with other players yet.

                           -------------------

Q: When will we have joint-stereo support ?

A: Soon ! In fact, the Joint-Stereo support is ready for some files
but it is too slow to run on a basic Falcon (and there are bugs). Splash
wants to listen to joint-stereo on his basic Falcon, and so, decided to
make completely new requantization subroutines, based on optimized ISO
sourcecode. Wait and see...
