Saturday, February 16, 2008

comparison between mp3 and wma codecs , (linked pdf file )

You can find it in these links (direct pdf files , please use "save as" with the right mouse click , or press ctrl + for opening into your web browser.
The file is just 200 kb.

multiply article
geocities article in case the previous does not work

The file shows the methodology i use plus a big table with compressions in wma FhG and lame mp3 vers 1 codecs in terms of spectrum analysis
This file has been originally edited on 2005
Please leave here you r comments

Oversimplified listing of the MP3 compressions

This is an notice shown on the  same webpageand also refered here separately.  This just describes the various compressions levels and thier main use



Here is a oversimplified listing  of the MP3 compressions :Notice that as the number in the left pane is higher ,  the  higher the filter and thus higher fidelity audio. The higher numbers can offer the abilities or the  lower numbers  too.  
Notice: The program  used  for analysis  is Music match jukebox that offers  the  curves shown in my
blog above

kbps

approximate usage -

8 - 11 kbps

suitable for recording telephonic conversations , voice  recording . narrowband AM radio

16

the above plus high fidelity  speech, AM radio, low fidelity streaming radio

24- 32 kbps

high quality speech , AM radio [medium and shortwaves ]

44-56

low fidelity FM radio

64

older fidelity FM radio

96-128

CD  quality audio

192

studio CD quality -

256

'Store'  mode for CD  quality


and for WMA - fior anyone interested , as  tested with Musicmatch Jukebox . For me  mostly

5-8-12

 just simple voice recording

16-22

high quality speech recording , 22 seems  as HIFI

44

 good for FM

48

CD audio  compromise , best for mass storage

64

CD  recording   = 128 on MP3

96

'high quality' CD recording =192 on MP3


And notice the  following:
The above listing is still controversial  and depends on the program and codecs you use. Older  lame codec [used in goldwave ] does not offer the same audio quality

And several  comments on windows media wma files:
- offering lower dynamic range :  they can clip very low voices , The  dynamic rrange  is aoubt 50 db
- on MP3 hardware players :
   - they can drain the double current (Sansa E130  and Creative Zen Plus  ).
   - in most older MP3 players i tested (as sansa 130 ) , the WMA codec  can  offer better audio than its MP3  codec!!
   - the  wma codec may introduce its own noise  with 'cracks' in sudden audio changes  or in loud points. See also the http://zlgr.multiply.com/reviews/item/32

The reason not to use low MP3 compressions!

Notice : this aricle is my 2nd arcticle on mp3 tech and appeared on 31-5-7 on multiply site . The main reason writing that article is that many  people  are using  low level MP3 compressions (as 192 adn 256 )  that i do not think  are  so necessary  since per  my measurements  128 kbps are more than enough. To my year  wma's  of the level of 48 kbps  have neatly the  same level .



--------- Given that many users on Multiply rip or covert their music in quite big files of over 7.5 MB fr a 4 minute song ,i decided to write this article to explain why it is not necessary to use very high sampling rates.

At same time I will notice to you why I use the WMA format in 48 kbps to include mass material into a small MP3 player as shown in my previous reviews

It is important to advise you that I was in the audio technology and HiFi's since 1980 , including also the MP3 tech form ca 1997 and my first ever MP3 player was with CD on 2000.Also i used several professional equipment the older days and I know very much about it.

This is a abridged version of my blog in http://zlgr.multiply.com/journal/item/41 with a little more explanation in the pictorials If someone is still very boring to read this whole message ,please check the flies on the http://zlgr.multiply.com/journal/item/55 for his personal evaluation , though it is very worth of reading

And here is the basic background for the above theory .

1.Make a file with white noise . This noise is used primarily for testing purposes in audio laboratories. it can be used to measure the linearity of audio systems including the audio part of radio transmitters. The easiest way to make this white noise is with the Cooledit program.

For best measurements i made a file of 60 secs making a file of 10M336B [10336 Kb]I also deliberately use the linear frequency response in order to find more easily the cutoff frequencies than with the standard logarithmic freq response

click to view the original file This is our original WAV file's frequency response , designed from a white noise of 0 db level. As you may notice it is a totally linear, and will be used as reference to the results from various compressions shown later

2.Convert the files toMP3 and /or WMA in the most popular conversions . I choose the MP3 format on 128 [standard]192 [broadcast mode ] and 256kb [store mode] while for WMA the 44 [FM] ,. 48[I say just CD] 64 [default near CD ]and 96 [CD ] kb.

I always used the Musicmatch Jukebox in its 6th version which is very light comparing to the newest versions and has very good results especially if converting from CDs and MPs to WMAs . And though Cooledit has MP3 save option

3.View the resulted files back to Coledit's frequency analysis screen

:

256a
256 kb
.
As you will see the 256 kb sampling rate offers a very high audio bandwidth of ca 21 kHz filtering out everything above this frequency ,with more than 60 db cut off .But these cut off frequencies are inaudible to the ear ..
Tthe file size is 1876 KBytes
click to view the original file
192kb

The curve here goes to the 20 kHz , and about 60 db cutoff above these frequencies. This is the maximum the ear can listen The file size is 1407 Kb
click to view the original file
128 kb
And here is the standard MP3 with strong cutoff above 15.900 Hz . I do not see any significant difference between 128 and 192 in my ears though still 112 with a cut off at 14000 and 96 kb at 12000 sound nearly the same
The file size is 938 kb on the 128kb

WMA s in discussion

AS Cooledit cannot open WMA files , i used first a third party program to convert the WMA files iinto WAV and then opened with Cooledit , and here are the results :
click to view the original file

48 kbps

48 64 and 96 kb

Here all the WMA files have the same audio bandwidth at 20 kHz with the only difference on the dynamic level. ,
click to view the original file

64 kbps

The dynamic level is ca 36db , for the 48 kb , ca 40 db for the 64 kb and ca 55 db for the 96 kb compression. The 40 db are the audio levels used by most music groups. More than 60 db are used only by classical music And the file sizes are 367,484 and 718 kB respectively . IN practice that means that all these modes can offfer just high quality audio though very low audio levels are 'removed' .
click to view the original file

96 kbps

In a very careful listening you can see some minor artifacts on the 48 kbps especially in drums and high trebled audio.

click to view the original file

WMA 44

And here a funny case of the 44 kb WMA. Instead of having a smooth cuve , that reminds a triple 'treble control' , a part of the bandwidth is somehow cut out

However this happens with the MMJB 6 . Using another converter as for example the MP3WM OGG converter, the results are also diferent . The results in the MP3 conversion showed me a flat bandwidth for 128 to 256 to 22000 with 96kb having -6db on 16000max .while the WMA compressions rates were showed as a bandstop filter analogous to the compression rate ...



Furthermore these are the results with the over mentioned program . I mean , using a different program to convert files gives a different result
AS for example Cooleditwith its MP3 plugin ca offer linear response to the maximum of the bandwidth.

At another example i was also using the ACE mult iformat converter . The results once opened or converted to WAV (for WMA) have made several interesting results . Please see the picture below, it is an animation!


ace+mmjb

From the above results , it is clear that ACE can technically offer better audio than MMJB on the MP3 format , but worse than MMJB in te WMA format

MP3 comparison chart of two encoders

Please notice that this is the first article i wrote abut mp3 tech analysis , depicted on 96-97 and appeared on my old geo site


UPDATES ( i think made on 91-92 ):

Following a series of upconvertions adn other experiments that itme i have found soem other peculiarities that are main to Musicmatch:

  1. Upconverting monophonic bit rates to stereo bit rates can cause stereo widening of these monoral audios. The lowest stereo mode i found or used was the 24 kbps
  2. UPconverting to higher bandwidths may cause / produce 'reaction /reactance carriers' . For example a 8 kb ( of 8 kHz) upconverted to 24 kb cana cause ahigher freq whistle to be heard, that can be soemtiems very annoying. please notic that this does not only happen between MP3 converions but also to convert one WAV file of 32 kHz to an MP3 file of 44 kHz bandwidth . There was indeed one reactance carrier of ca 16 kHz . The problem for this case has been corected with the usage of Xing encoder
  3. Some low rate ( such as 8/8 , 8/11 and 16/11 ) MP2-layer 3 files seem to use a 8 bit audio resolution. Using 8 bit resolution WAVS to converting to MP1 ( above 64 kb rtates at leat ) can cauise the MP3 files to have the half sixe!!
  4. As you can see from the frequwncy responses tables there is soem important information that shows a nrealy direct relation of bandwidth and compression And here is a over simplified relation.Notice trhat : any freqs above this band-stop are sharply removed Onfo is for Musimatch with slight improvement on Xing for the theoretical noise example
  5. 160kbit - 44 kHz gives a 20 kHz bandwidth
    128 kbit -44 kHz gives a 16 kHz bandwidth
    96 kbit - 44 kHz gives a 11.8 kHz bandwidth MPEG 1
    64 kbit - 22 kHz gives a 10.4 kHz bandwidth
    48 kbit - 22 kHz gives a 6 kHz bandwidth
    32 kbit - 22 kHz gives a 5,2 kHz bandwidth
    16 kbit -11 kHz gives a .4.7 kHz bandwidth
    8 kbit -8/11 kHz gives a 3.3 kHz bandwidth MPEG 2

  6. One very important point when using players with low bit rates. It is very important to disable Doirect X from the player otherwise audio will be strongly


Following a long period of digitizing my music collection into MP3 I have also experimented with two different popular encoders and below you will find some very important results:
The experiments are two based upon a standard method .( tones and white noise)
Program for making these is CoolEdit Pro (trial) with trial MP3 plug in (read only)

Step A Making the files

A 1:

Tones produced are : 3 secs each tone , 0 db level , with the following frequencies ( all are Hz)

  • 1000
  • 5000
  • 7000
  • 9000
  • 13000
  • 14000
  • 15000
  • 15500
  • 16000
  • 18000
  • 19000

and saved as WAV 44.000. mono , 16 bit resolution

A 2

Making white noise again under CoolEdit with:
1 sec blank
3 secs stereo white noise of 0 db level
1 sec blank

with 48000 kHz , 16 bit resolution

Step 2- compressing

Using the two compression programs ( Music match 5 and Xing encoder 2.1) step by step in various compression levels :
VBR - 160 – 128 – 112 – 96-80- 64- 56-48-32-16- 8 then save each produced file by compression – name
All files are then archived into a ziped file for later references
And here are some interesting and funny results ater zipping :
WAV files are expected to be compressed , nearly to the level of standard Xing compression
Thed tone file was 34.560.444 bytes and zipped to 558960 bytes
But still , Xing , tone compression , seems to still compressed at high rates . files of abt 720 kb have been compressed to only 9200 kb! See below for more

Step 3- checking compressed files back on Cooledit – commentary

Cooledit pro has been again used for chacking the produced MP3 files . After loading files a smoothing process has been calculated ( RMS levels )

Part 1 the tone response

Very surprisingly both encoders shown a ‘peculair’ attitude towards the pure tones by producing faint signals of lower levels , up to –8 db .
Both compressors did not respond to tones above 17000 kHz leaving only blank audio and ‘clicks’ between tone freq change

Music match 5 , shown a very big number of faint signals ( about 15 .) nearly as it happens with Xing encoder under VBR but levels were higher than of Xing . There was only the restriction of the bandwidth which nearly corresponds to the compression rate . More on this later
Xing however under 80-160 kb rates produced very clear ( faint free ) tones . IN some cases upper freqs ( below 17kHz) shown some ‘ripple’ ( on off ) faint signals of very low levels some hundred Hz above the main freq. VBR however was relatively ‘dirty’ as shown in the table below ( levels of 40 db or more

IN both encoders , tones of higher main freq. than bandwidth ( esp for rates below 48) produced mirror tones of 36 –40 db lower than main tone level

I have made also a try with WMA module of MM5 with results nearly of the MM-MP module

Part 2 the white noise response

While original signal was with exact edges between start and stop of noise, all MP compressed files shown a fade up and fade down of audio response ( either time or frequency domain ) as shown in the spectral view.

The table 3 shows the response of the 24kHz stereo white noise showing the decibel points

While Xing had the same audio level , MM5 had a 6 db loss

Xing also had nearly flat freq response at 99% of the spectrum while MM5 had a slow decrease response over higher freqs ( points shown )

Also 112- to 160 rates on Xing have the same response.. Though io could not see any significant differences in the spectrum alnalyzer of Cooledit, this can possibly lower the dynamic range .

MM in contrast shown a significant decrease of response dropping from 20 to 16 and 14 kHz for the 160 , 128 and 112 kb respectively ! Though playback on Winamp or MM player shows a 44 kHz range ….

Comparing to the response curves , in all cases except 16 Xing has higher response of 4-5 % than MM5

Special commentary on playback of the WAV tone file

Cooledit , as expected as playing very clear the tones .
However direct connection of line out from the SB 128 to the headphone showed nearly no audio on freqs above 9000 Hz ( mismatch??)
In contrast to it the HIFI connected same way produced all the tones till 19000 hz ( audible from the headphone output from HIFI )
Nullsoft’s Winamp 2.7 had a totally MP3 type audio (producing the ‘ghosts’or spur tones as shown in the Xing )
Also Media player had the same ‘attitude’
In contrast to it real Player produced clear audio in all the tones !

Add on : Time rates for compressing a music file

The table is self explanatory. Notice that this has been made last year when I used the Pentium 133 with 64 Mb memory (which possibly does not matter on the compression speed so much )
The actual WAV/ PCM file is a song of 5 mins 27.86 sec of a total 57.8 MB size
First list shows the constant rate while second list shows variable rate centered at 80 kb and variations of the shown level
The 3rd list shows times produced with the MP 3 compressor another program capable to produce MP compatible WAV files ( it possibly uses the Microsoft MP encoder) . IT also produces 8 kb/8kHz files


LIST 1

Responses of clear tones on Xing encoder on various compressrion rates


lo - nor Xing Lo var Xing Xing 160 , 128 112 96 and 80 kb 64 56 48 32 16
1000Hz 12 ……….1000

-40……….5200
-42 ……….7200
-48 ……….11600
13600 ……….1800

-38 ……….5100
……….7220
……….11500



3000 50000 7000 9000 11000 with -40 3000
5000
7000 /-47
9 000
1000/-50
3000/-36
5000
7000/-24
5000 Hz -42……….200
-32……….1200
-30 ……….2800

+12……….5000

-24……….7500
-38 ……….9600
-36……….11200
-44……….12300
-42……….14000
-48……….14600

……….200
-32……….1100
-30……….2500
-25……….7500
-37……….10000
9000,

11, 13, 5 17, 19 21 kHz with –72

9000,

11, 13, 5 kHz with –72

9000,

11, 13, 5 kHz with –72

1000 3000 7000 9000 1000 ……….-36 3000
5000
7000 /-32
9 000
1000/-40

7000 hZ (+12) -40……….200
-34……….700
-32……….2100
-44……….2600….
-22………4500…
> -36……….12000
-38……….13200`14200
-32……….2100
-24……….4500
-18……….9100
-32……….11900



Clear Clear
9000 Hz -42……….700
-38……….1800
-30……….2700
-32……….4200
-20……….7500
-13……….11300
-30……….13900
-38……….15200…
&##8230;….16100
……….500
……….1900
……….2900
……….4900
-20……….6780
-15……….11200
15 and 21 kHz with-60 db 15 with-60 db - 3000 ghost @-24 3000 ghhost/-24
13000 -38……….1000
-40……….1200
-30……….5800…
𕢦….6800
-26……….8100
-14……….10700
-9……….15400
-26……….17800
-24……….19000
……….400
…… .1000
…….15600
-36.….3500
……...3800
-32….5800
…….6200
-32….6800
-26….8200
…….8500
…….9100
-14….10600
Clear Clear Is cldear ( no signal) 10000 ghost @-32

14000 -40……….200 1200 2000 2800 48005200 10100
-32……….41200
-30……….6800
-24……….7800 .9200
> -13……….11800
-8……….16500
……….15000 .15500
only for >30

-30….7800…8100
-24….8800….9100
-24….10100.11200
-16….12600..13100
-6….17600….18000


-72 with

2000

6000

10000

18000

20000kHz

Is cldear ( no signal) Is cldear ( no signal) 9000 kHz ghost @-20
1000/-24
15000


Is cldear ( no signal) Is cldear ( no signal) 8500/-24 db ghost
5000/-24
15500


Is cldear ( no signal ) Is cldear ( no signal) 8000 /-32 7000/-23 0/-24
16000 Is cldear ( no signal ) Is cldear ( no signal) Is cldear ( no signal) Is cldear ( no signal ) Is cldear ( no signal) 7000 /-23 db 8000……….30 1000/-24
18000 Is cldear ( no signal ) Is cldear ( no signal) Is cldear ( no signal) Is cldear ( no signal) Is cldear ( no signal) 5000/-24 db 5000 ghost /-24 2000/-24
19000 Is cldear ( no signal ) Is cldear ( no signal) Is cldear ( no signal) Is cldear ( no signal) Is cldear ( no signal) 4000/-24 db
3000/-24

Lo - nor Xing Lo var Xing Xing 160 , 128 112 96 and 80 kb 64 56 48 32 16


FILE SIZES

Rate

Xing Size

Xing Ziped

16

71928

5159

32

143904

8748

48

215856

14533!

56

252158

7722

64

288192

8263

96

432288

8151

112

504336

8653

128

576384

8947

160

720480

9227

LO NOR

287296

216502

LO

336871

274009



RESPONSES ON WHITE NOISE FOR MM5 AND XING ENCODERS

WAV FILE HAS
1 SEC BLANK – 3 SECS WHITE NOISE – 1 SEC BLANK

AUDIO LEVEL IS +3 DB

Rate

xing encoder

M M 5

FILE SIZE XING

var low -6 db<13.5khz
30864
var lo no -6 db -60 db 20
36027
var no -6 db -60 <20>
42860
160 0db -38db/21. -2/2k
-6/16k
-11/ 20k
100320
128 Same 2 to 6 up to 16 80256
112 Same -6 to 14k 70224
96 0db <15....> -6 /11.8 60192
80
0 <10.1>
constant to 11000 @-6 50400
64 0<3,4> const to 10.4@-6 40320
56 -6 /9.2
-45/9.6
-6 to 8.8
-60 /9.2
35280
48 0
-2 /3.4
-6/7.6
-6/6k
-60/6.2
30096
32 0
-2/5.1
-60/5.5
-6 /5.2
-60/5.3
20160
20
-6 /3.8
-60/3.9

16 -6/4.0…
-60/4.1
-6 /4.7
-60/4.8
10008
8
-6/3.2
-60-/3.3


TABLE 3

Times compression ratios on A FILE

Using A 133 Mhz Pentium 1

file : wav 44 khz 16 bit size 57.834 kB 5:27.86 sec (327.86 sec)

Music Match 5 under

Mode Kb Range Fielsize Comp rate Time elapsed
8 8kb 11khz 328 kB 1/176 1:02 min
16 16 11 656 88 1:19
18 18 11 - - 1:22
64 64 22 2623 22 2.22
96 96 44 ~3924 15 2:45
128 128 44 5246 11 2.51

~ estimated

v 1%
78-79 3222 18 2.49
15%
81 3366 17.1 2.46
88%

5982 9.6 3.00

mp3 compressor

16 16
657 89 1.43
128 128 44 -
>5 min

Crash testing with Napa DAV315

Crash testing with Napa DAV315
version blogspot original article here in Geocities

Following my interest in MP3 technology the last years and the big list in MP3 in songs recorded throughout the years, the information read from many magazines and e-newsletters and web pages , I have finally decided that a MP3CD player could be the ideal solution for me to replace my walkman and my other CD player. This was also the result after a recent purchase of a CD recorder whose main use will be at first for any necessary future backup at first as well as for collecting this material just in MP3CDs

The S/N of the model is DB02007083 manufactured April 2001

As you know I like to make inspections of any interesting gadgets. And here is an exhaustive analysis for the Napa 315. And much better as I recently bought a CD recorder that helped much in makling a line of Cds for the testing and normal playback of my big collection of more than 2500 songs from tapes , Cds and SW recordings .

Before of all just to notice : Although volume is OK for headphones with number s till 6-7 , when connecting to a HIFI , the level of 19 connected to the headphones socket is very low . line out is also much lower more than 6 decibels lower and still adjustable by the vol level. ( possbly below the 15 uV though 200 uV are the standards on all audio equipment !! )
316.jpg (31272 bytes)

Part 1 - appearance
Appearence:
This model has a very nice 'trendy' Appearance supplied in a plastic firm pack and includes a mains power supply with the uncommon level of 5 VDC of half width than any other commercial power supply I have ever seen , two NimH batteries , a belt , a stereo jack to 2 RCA for connecting to hi-fi and earphones
.
4 buttons are from the left side acting having slightly different functions between CD and MPCD operation the and 4 buttons from the right side having a a button lock , two for digital volume and one for various modes ( ie acting as menu )
Battery charger
This means that CD player has a built in battery charger requiring to abt 15 hrs to fully charge the batteries. It is required to charge in full. Their nominal storage is 1.6 Ah . LCD also shows the battery status with 3 level bars . I t seems that the adapter is still charging while NAPA 315 is playing. Actually the voltage as measured with multimeter shown 4,68 VDC and must be connected to mains supply if plug is connected to the unit , or the unit is NOT working ..
Also in case of low bateries the unit plays the song and stopsd after rebuffering

Instruction guide - acessories

Its instruction guide uses very small letters. I suppose they use fonts of 6 picas and smaller in the case of the gray notices. Although for me is a bit OK with the gray notices to read a bit difficult , I think that a little bigger font could be better for reading
The belt is relatively big for the player's size and quite wide and thick . It mostly reminds usage of …. professional photo cameras

The headphones are very typical with nothing impressive Just a little treble from abrt3.5 kHz and over , regarding to my Kenwood DPC183 open air headphoneswhiu ch i use as standard headphones also in DXing.

Part 2 Operation - buttons playlists

Using the buttons
When playing any Audio CD the search skip buttons act as FW and REW When playing MP files they act as file search , unless [DIR] option from mode is used

Now for the [MODE] button . It works like a menu with many options show in brief and how buttons are used
RPT  (repeat function )
/ one (repeat continuously same song)    next  prev work OK
/ all  (again from start)      next  prev work OK
/ dir  (repeat only what is from this directory)   next  prev work OK
/ int  (play only the first 10 secs )     next  prev work OK
/ rnd  (random play and stop at end )    next : next random  prev; NO
/ rnd all(random from all directories)    next : next random  prev; NO
/ rnd dir (random from this directory only )   next : next random  prev; NO 

E (equalizer)
/ cls  (classic music)
/ pop  (pop music )
/ jaz  (jazz music)
/ rck  (rock) They are spectrum analyzed by software and info shown at end of this file 
File / dir (sequential selection of files or by directory ) 


LCD
Now for the LCD . When operating it shows if the CD used is a AuCD or MPCD and even (undocumented!) VCD. At left down shows the serial number of the song, as it does not show any ID3tag or even a filename,which is a feature only in the next model 516, and the time elapsed. As also other reposrts refer 315 does not have a backlight I m not interested in it as i always use it near to a fluorescent lamp.

It claims to be capable to support directory searching, CDR/W disc and multi-session and it is tryue . See later about this
Playlists
I did not tried , but as documented it can make a playlist of maximum of 32 tracks

Part 3 MP3 usage
Incorect loading of MP3 CD
The unit displays Err 3 . I do not know the code but it seems to load the Cd again ( and press a little more)
File numbering and sorting - possibly the first most important feature
Here is something regarding the file numbreiung
315 uses the way a directory sorting uses. This is exactly what a dir *.mp3 /s under DOS can show I have seen that it has a direct relationship to which buning program has been used.
For example with usage of Nero ( Mode 1 and MOde 2) and Easy CD 3 or 5 give dirferent results:
More clearly
Nero MOde 1      mode 2      Easy Cd
0-9     0-9    0-9
A-Z    A-Z caps all   a-Z case insensitive
a-z 

Also in case of subdirectories the sequence of sorting goes this way:
C:\
C:\A\A
C:\A\B
C:\A
C:\B\A
C:\B\B
and so on
Maximum nmber of tracks recognized
I also verify the documented maximum number of 630 counted tracks in a CD having exactly 1000 MP3s all made under 16 kHz sampling rate. ( total recognized time 45.49 hrs!) Documentation shows also in case of 10 directoriues the numbers pfrecognized MP3 clips can lower to 620 At first it was pretty good to recognize the list of 290 files of a total CD-A time of 72:48 in 12 seconds (MPs of 15 hrs total time !)
Playback of MP3s
In all cases , the unit first sees it as cd then idetifies if ti is a MP3 Cd or VCD then in case of MP3 Cd tries top count the numbers of MP3 files ( and tales about 5-15 secs for this) then starts to paly the first song with always at the preset volume of 19 .
The FFW and REW work only for file searching rather than searching inside the track
Here you will find a series of observations and mysterious conditions All recordings are made with Nero
- Crop of ends !!! If a music file does not have an end with silence , the player will crop about 0.3-0.4 secs from it ( and possibly caounter will roll )
- VBR and constant rate while playing a VBR song 25% of 6:25 mins length the counter in many stances stopped for a few secs or minutes untill showing the end of the song
- IN many cases isaw that at the end of the songs of rate of 96 kb the counter was rolling too fast This especially happens when using Trimmer MP3 trim to trim out the ends of a song
-One also peculiar case : During random song playback , epecially if number diference is too high , the unit seems to hang up. .This problem is most significant when burning is set to TAO ( track at once) , but onDAO ( disk at once) the problem still happendss especially if unit is only battery operated. The motor spins veryfast , just recognizes the song but ddoes not start playback.
- ECD 5 : Counter neer shown the exact number of MP3 files in included in the CD.
I do not know what is really the problem but ECD5 seems to be problematic especially for the MP3 Only as a typical computer CD is recognized in full

Bit rates (tech)
Using the older tactic for MP3 testing , as shown on the specialized page , I re-used same files to check the ability of the NAPA player to playback them. Here are the results

-Constant rate
320 250 192 160 128 112 96 80 64 56 48 40 32 28 20 18 16 8/11 8/8 .
From these standards only the latest two were not recognized by the unit just the time counter rolls fast till end. See at the end of this paragpah for more.

- VBR 5 scales per Xing . Counter was rolling normally.
- steps of 10% as per MM5 Both ways have been heard perfectly
- a tone of 1000 Hz for auudio level check .more for this later
- fake MP3 from a .wav file ! Tough all programs hung , program did try its best to play the file as cratches and hisses .Stopped finally but not hung
- test audio with 8 bit resolution at various bit rates . All files olayed OK with the same audio, even soem older files shown a diferent dynamic audio range while playing on Winamp
- new MP3 plus (128 ) mode also played OK but with the 64 kb rate
- 8/8 and 8/11 modes shown many peculialrities. BY instances the unit played them well , by otrher instances the unit did not pleyd them, but just counter was rolling very fast.
-unit produces high frequency hiss for rates lower than 40 kb gradually increasing as rates are lowered

WMA and RA, are not recognized . Could like to see something later to recognize both formats !

Multisession
It plays normally in multi session . However it seems to have a problem when the new session is in the root directory and previous sessions are in directories and also in cases when buffer underrun has been happened. ( tghough still the unit can paly the CD tll the bad sector)

In a few cases when new files are on root directory, the unit tries to recognize th CD , starts to play the first by letter and after 5 secs it stops playing ( hung)

This hanging found also in some ogther cases esp ewhen the file is at the end of a doirectory

Antishock and buffer NEW

Buffer: the unit has a 120 sec buffer as ESP checked as when the unit re-reads the CD( rebufering) . I have checked with 96 112 and 128 kb files for the moment and found that rebufering can happen 116 secs from start of song for the 128 kb rate and every 116 secs to restart reading CD . For 112 and 96 kb the times to 're-bufer' are 130 and 150 ( instead of 160) secs respectively .

Antishock and car usage :When drivign in a good quality asphalt roads there is not a ny problem. However as in Greece many roads are very old or remade , when driving over harsh asphalt roads with 80 km /hr or more , antishock mechanism can shut off the unit after 1-4 rebufferings . I have found that using a small face towel the problem can fully be solved .Just fold the towel and put the CD unit with three levels of folded towel

Antishock and buffer

Buffer: the unit has a 120 sec buffer as ESP checked as when the unit re-reads the CD( rebufering) . I have checked with 96 112 and 128 kb files for the moment and found that rebufering can happen 116 secs from start of song for the 128 kb rate and every 116 secs to restart reading CD . For 112 and 96 kb the times to 're-bufer' are 130 and 150 ( instead of 160) secs respectively .

Antishock and car usage :When drivign in a good quality asphalt roads there is not a ny problem. However as in Greece many roads are very old or remade , when driving over harsh asphalt roads with 80 km /hr or more , antishock mechanism can shut off the unit after 1-4 rebufferings . I have found that using a small face towel the problem can fully be solved .Just fold the towel and put the CD unit with three levels of folded towel





Other modes

CD audio and related features:

As about playback of different Cd types this already has been discussed. I t plays all the types - originals and computer copies , without any problem
A default operation when using CD is the120 sec antishock protection and can be disabled by the mode button . ESP is also shown in the LCD
IN contrast MP3 has this facility built in


Support of CD-A formats and models
As a multisession , multi type reader , it plays all the Cd ytpes , even the types that computer drives and CD players do not 100% support !


Example 1 : INTENSO CDs are not supported on my 52x drive. The NAPA player did support it very well
Example 2 . Recorded a 20 track CD-A from various kinds of music and different formats (MP3 and WMA) with the use of the bundled Easy CD 5 and 'CD text' and with various speeds on NONAME (bulk) CDs . The result has been tested in Napa , two Cd players and our HI-FI and here are the results
Nero has been lent for this purpose only.

Prg used and CD AIWA KENW1 KENW2 NAPA
-------------------------------------------------------------
ASKA NERO TAO 10x # + + +
Bulk ECD5 DAO 8 x # - - +
Bulk ECD5 Dao 6 x # - - +
Bulk ECD5 dao 4x # - + +
Bulk NERO DAO 8 x buffer underun
Bulk NERO DAO 4 buffer underrun

Philips CDA ECD3 +/# +/# + +
Intenso ECD3 + # + +





ASKA was the best CD used for the moment ( 10 x as standard)
TAO=track at once , DAO= disk at once ECD = Easy CD creator ,prg bundled with



Notices :
Aiwa shown mechanical jitter/problems when trying to identify the disks, nearly in all the cases except Philips recorded at 4x. At most cases it had to 'wait' for 10 secs to read the sectors., then counting tracks and starting after a while to play tracks . In many cases denied to work

Kenw 1( DPC 183) is my walkman It immediately read the ASKA CD even if is recorded at so high speed , though older recordings from a friend with ECD 3 shown two very bad points of 'skipping' ( unable to read ) and 'shifting' ( next sector)
Kenw2 is another walkman used for the test, It shown 100 % accurate readings from all 'problematic' Cds per DPC183 walkman
NAPA read all these systems without problems





VCD :
The CD I used shows 3 directories a CDI a VCD and a MpegAV with the real data with .dat shown instead of .mpg or .avi
The VCD I have is an album of Andy a very good hit Chinese singer and audio used is matrix encoded ( ie L+ R and L-R are heard instead of pure L/R.)
Is this the Chinese standard?
Have not other VCDs to test
Just for reference this VCD is played exactly as a classical audio CD with the CD rolling continuously once it is played
The FFW abd BCK buttons of CD work here as track change
No antishock info is shown on the LCD during this mode





Playback on Multisession , mixed CD and VCD


Again both programs ( Nero and ECD 5 ) have been used with various results shown here :( and too many cds have been burned for this)
And soemthing other. In case of a damaged CD or dead points on its surface, the unit can show the serial song number but most times canot play the song (irregular counter time , irregular sounds and hang ion) . In this case you can select the next track


Nero
Nero with closed session worked perfectly on NAPA
Nero at multisession : NAPA found all directories on multi session CD and played them well ( in contrast to ECD5)

ECD 5
MP3 only 2 sessions: 214 out of 258 MP3 songs have been shown , the 2nd session track was not recognized!
Mixed CD with ECD5 : CD-A tracks were not recognized only MP files have been counted by player but could not play them ( just show 00.00)
Newer session over it: still no playback
ECD5 with MP files only: again nothing


Original albums
Mixed cd and VCD ( avi): VCD shown at the LCD of player, the CD rolls continuously , the CDA tracks are shown, but nothing more happens ….'
Video CD : (list of files on root, video files in directory as .dat ) :song were recognized and played well
MP3 Mag CD the MP3 files have not been found by the player ( MP3 files were in sub directory )




APPENDIX -TECHNICAL ANALYSIS

Volume and outputs

The Player uses a digital volume with 32 steps
After CD starts to play , the player uses the preset volume set of 19 ( of a total of 32steps ) which is too high in a quiet environment
At same environment with normalized tracks or MP files the best volume set is 4-5

IN contrast when connecting to a HIFI, the volume must be set to the predetermined level and use the ear jack ( 19) instead of line out total output will be very low
Line out: Its level is much lower and is adjustable (!!!) by the volume control at 6.5 db lower . It is something I dislike because line out must always be fixed level

Playback of MP3 rates below 40kbit shows a hiss re-generation audible especially at the lowest volume levels ( 1-5)


Audio levels for 1 kHz sinus tone /-6 db MP3 audio analyzing software from the ear output . For the line output please subtract 6.5 db

0 60 Noise Floor
1 48
2 43
3 38,3
4 33,6
5 29,9
6 27
7 25
8 23
9 21
10 19
11 18
12 17
13 16
14 15
15 14
16 13
17 12
18 11
19 10
20 9
21 8
22 7
23 6
24 5
25 4
26 3
27 2
28 1
29 0
30 1
31 2
32 3



Equalizer and audio response
As shown above there are 4 equalizer modes: classic, pop jazz and rock
Tested with a freeware computer spectrum analyzer program and have seen the following results with a white noise file as referred above :

FLAT -7 0
-12 12000
-22 21900

CLASSIC -8 <400 span="">
-12 4000
-15.5 13000
-16.3 14000
-19.2 21000

POP -12 1800
-16 14000
-
14.5 14200
-16.4 20700
-26 22000

JAZZ -11 4000
-15 10000
-17 10800
-21 2000

ROCK -10 250
-14.5 1000
-12.5 4000
-17 20600
-32 22450





Testing the random numbering with 258 MP files
Try1: 001 202 134 184 186 018 143 118 174
Try2: 001 110 104 005 217 158 137 238 210
Try3: 001 020 027 239 251 229 138 083 094
Try4: 001 248 025 239 253 170 126 231 012

Therefore there is not any standard randomization



Conclusions


As shown with the above tests , the NAPA 315 seem to be a very good CDA, VCD and MP3 Player except very few peculiar cases.

IN general I m very impressed with it and the MP3 ability to exceed too muchof the time of any CD or tape player without changing tapes or CDs As for example with the MPCD refered at the start of this web page, with 290 songs, recorded at 96 kbit, had a total of 15h 10 minutes of total playback, 630 MB of space used or 72:48 Cd time !

SINPFEMO A better signal tech analysis by using F/TDM

SINPFEMO
-------------
A better signal tech analysis by using F/TDM analysis drawings in specialized reports
(version blogger )
Considering that SINPFEMO does not 100 % cover the truth from listeners point of view in regards to signal readability QRM and fading I have used for more than 4 years derived from more specialized monitoring equipment such as Hewlett Packard , Rohde & Shwartz etc
I think however that both terms shown below are very easy to understand however there is still a little analysis behind them on how i used them so far.

#1. Frequency domain analysis
...................#1b. About computer DSP analysis on FDM
#2. Time domain analysis ( fading analysis)
...................#2a.Cases of 'Short' time fading found on SW:
...................#2b.Cases of long term fadings
#3. More advanced way for domain analysis
#4 Using R75 and specialized programs New.gif (908 bytes)
....................#4a Smart Icom 32 and R75
....................#4b:Use of DSP and R75




1. Frequency domain analysis
I used two types of analysis -with the help of a drawing. The first way is with the use of bars and the second with the use of bell shaped curves that still can show on how a signal could be QRMed from a nearby station . As that times my older receiver HF150 or previously SONY IDCF7600 D did not include S meters I was unfortunate to deliver drawings with accurate drawings, Instead of it my drawings were made with the totally subjective audibility standards as used by the SINP(FEM)O standards
Nowadays the usage of ICOM R75 with its AFC derived S meter fixed a bit of this problem. There are still not 100% accurate readings as (modulated) signals exceeding S9 levels are still not correctly read !For a level with the R75 you can still do a little more by using ATT (-25 db ) and then preamp ( in any scale from 10 or 16 dB ) in order to record the fading levels
This case be done more easily with more specialized interfaces such as SDU from Grove ( direct to IF stage if receiver permits ) or by using laboratory surveillance equipment ( the o.m. models of HP , R&S etc)
However there is still a question on which is the best way to measure the signals for receivers as R75 :
1.The one is reading on the S indicator during AM / AM Narrow
2. The second is checking the signal with CW analysis and using as narrow as possible bandwidth in order to narrow down the width of carrier (??) and clear out from the modulated signal.
Below is the idea with pictures. Please save this file and these pictures as under this analysis they may not be clear
Please open picture in a separate web pagePicture with bars:
The above picture is from very old logs for Vo Malaysia on 15295 during the times 93-94 with VoLiberty shown at left part and RFI ( France ) at right. Of course it can not show any QRM problems encountered
Dotted lines show the depth of fading.
This is my main way for signal reporting
Picture with bell curves
This can show clearly the QRM problem from both stations though still cannot deliver any problems encountered by modulation though this curve can oversimplify the term modulation when used on that manner (I found many signals being quite strong but low modulation)
Picture with modulation analysis
This is possibly the most accurate way to describe the characteristics of a signal that can also show the modulation index as well as tha audio quality. But how easy id for anyone to do it? I think that ONLY computer made techniques can do it or real time analysis by the specialized equipment can do it (?)
+With the spectrum analyzers you can too see any carriers and other signals that can lie inside the passband++
Of curse still co channel QRM cannot be seen this way except the aural way ....or with the use of LPDA antennas
+++added 5-5++
1b. About computer DSP analysis on FDM
Fortunately with the use of modern computer analysis with soundcards and the shareware audio programs such as Cooledit part of FDM can be analyzed relatively easily. For example Cooledit has a spectrum analyzer. This way audio snippets from either side of signal ( LSB and USB separately ) can show not only the modulation levels (and calculating the index - providing that signal is off tuned ) but also show any other carriers that lie inside the (pass)band with greater accuracy a/o strength that any HF receiver can show

2. Time domain analysis ( fading analysis)
This is the second part of the most significant information required for a station (I think ). From many measurements I did so far over the years I found that there are two types (at least) of fading , the one is a 'temporary' fading that can occur in a less than 2-3 secs and another fading that can occur in times of minutes
2a.Cases of 'Short' time fading found on SW:
Short time fading #1
This is the main technique to show in most cases. Though a little arbitrary drawing this is one of the most common cases found on HF. As anyone may understand from this drawing this is a sinusoidal curve ' and refers to only 'clear' signals ( free from QRM)
Example #2
Another clear signal found esp. on 5 MHz band Notice on how it was the lower part with a small fade up
Example #3 ( Angola 4950 )
This was another example with signal a little steady and sudden fade outs
Example 4 Co channel QRM
Unfortunately this drawing could not be easy to made by computer this is the reason i remade it by hand.

You see here how the signal fluctuates. It comes mainly when another signal is on (accurately saying: nearly ) co channel QRM with 'shortest fading levels- depths ' coming from the signal difference between QRMer and QRMed signals while the frequency comes from the freq deference between the two carriers

This case can happen also to clear signals with much higher fading levels ( depths) sometimes as in 18-4 -2000 when most of the signals on tropical bands had a fluttery of more than 4-6 S units with a >3 Hz rate probably due to ionospheric reasons
These are 4 examples found on the SW band but there are too many others I found so far
2b.Cases of long term fadings
From my observations there are not so many long term fadings. One can be a steady signal over the time and another with very deep fades occurring every say 5 mins ( this can happen mainly to stations less than 2500 km far from the RX system ) but here also are the fadings caused from fade ins , fade outs and ionospheric conditions as will be shown below:
Long term #1
Here is an example - case of R Tirana some years ago and nearly the same for R Netherlands IND service
The signal was steady for abt 6 mins then jumped down to S3 for less than 1 min
Here the 'short term' fading levels are not shown
Long term #2 fade in curves
Here is a reference to SBC Warna 7235 ( Signapore) two months ago. The signal on abt 1400 was too low of the levels S5 but gradually enhancing to stand up to S 20 from at least 1515
Nearly the same can happen with fade our curve

Case #3 : ionospheric problems
Here is a case found on 18-4 -2000 when listening to Namibia on 3290 and 3270 . The case here is for 3270 with a signal steady until 1810 at S9+10 db but afterwards gradually lowering toS7 and standing there
3. More advanced way for domain analysis
There is still another way for making a exact F/TDM analysis that can be completely made by computer. The method is relatively simple by showing a predetermined spectrum of say + /- 15 kHz - or a wide as cases require to show the spectrum in a given time say 1 hr and on a 3D analysis.
Though not 100 % sure for this it was a special model tracer from HP that with the combination for spectrum analyzer has given the results in a thermal paper

UPDATE COM ON BOYS!
4 Using R75 and specialized programs
4a Smart Icom 32 and R75
ICOM offered a control software CS-R75 or RS-R75 as optional . This year Aug 2001 i asked th e importer to order this control software at a price of USD 42.5 as they previouslsy told me.
However after two months of waiting, they finally advised me that this control software has been given up production. Fortunately from the ICOM R75 mailing list have found the software of Mark Fine Smart Icom 32 which operates directly with the receiver with the use of a serial cable 9 pin RS232.
Using this software for spectrum analysis was a but tricky at first but then it was very easy. Just you have to determine the l two VFOs first the A as starting point and B the ending point. Sweep radio was however very low and I had to adjust the line pacing ( in the preferences) as low as 15-18 in order for the software to control as fast as possible ( In the preferences dialog - communications tab) with speed as high as 19200 And in the scanning parameters with delay as low as 10 ms. And still the speed was very low at a rate of 5-6 steps per second!
With as many sweeps as possible you can have a real conditions result that can show minima and maxima for each stations you determine.. Stopping the sweep , for two sweeps you can have the average level , but for more sweeps i m not usre if thsi can show the latest sweep or the average level ( RMS)
The result of sweeps can be saved for later reference.
Notice that still under this way you can still see only the contiguous channels ,but not what s inside the channel.
And here is an example:
Here is ana example for spectrum analysis. This is for a report for V of Nigeria on 0909 on 11-11
4b : Use of DSP and R75
The idea has been shown above on the 1b and is hown here with more detail .The basic infrormation however is that you have to use SSB with offtuining( IF shift) so that carrier can be shown. as reference for all mesurements. All is then rereed with pictures
Part 1 : Spectrum analyzer. It has been refered posibly cprectly on the 1b, and can show in parts the side band separately for each band selection .
Here is a capture of a signal in USB . carrier is shown at abt 240 Hz . YOU see a low level carrier at 500 Hz or 250 HZ above carrier
RMS levels of 20 sec of signal on USB for 11785 and shift of 500 and other carrier presumably same level .
Part 2 Fading analyzer : In contrast to above . i think that the correct for identifying the fading is with the AGC off . Tis is because the AGC can alter the S meter indications. Also in other cases I filter out the modulation parameters so that carreri to be pure and not interfere with the resulted carrier information
Notice that i am not 100 % sure if this way can really show the fading. level as it is audio based.
Case 1 : Fading due to co channel interference. Abt 4.5 HZz of fading? Trace for abt 10 secs Normalized , full wave
A relatively stable signal ! ( BBC)
15060 CBS Taiwan at 1200 for10 secs short term fading This picture is a close up of the picture shown as below.
15060 CBS Taiwan at 1200 for 2 mins -middle term fading . Includes also the above picture You can see the fading is somehow periodic.

Please tell me your opinions by return email to me at