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IMPORTANT: A very good trick to save some space

14 replies · 5,239 views · Started 10 February 2003

After 2 hours of testing the wav2amr converter using varius bitrates and samplings, I was very dissapointed by the reasults. The quility was bad even when the coding was succesfull (and that's because of amr's specifications), and also because of the limitations the converter had and the bugs, so I abandoned every effort on this and decided to see if there is any way to convert a wav to another type and at least to play it on Psint Multimedia Player.

Luckily I found (by chance and curiosity about it's relative name with cell phones) a codec that can compress the wav file, and it was also compatible with 7650 sound player(I haven't tried it on Psint's mmp) The coded files can be set as a ringtone as well.

And the name of it?

G S M (very relative and nobody ever noticed!!!)

I think it comes with all windows version because it has the microsoft brand(I am sure it is present on Win2000,Win98se and finaly on WinXp where it was tested). If not try either the latest media player or the nimo codec pack, they may have it.

You can find the information on how to convert your pcm files without extra software below(very recomended for newbies in PC's)...

1.Open windows sound recorder(almost any windows version has it).If you can't find it then click Start-Run and type sndrec32.exe (If it cannot be run you have to install it from the add remove in the control panel).
2.From there select file-open and choose the pcm sound file you want to convert or just drag&drop the file to the sound recorder.
3.Then go to file and select save as
4.On the next window click below the change button (it's next to the format text which shows the attributes of the file)
5.Another Window will pop up.On the format tab select gsm 6.10 and on the attributes select what you think is better(I highly recomend you to choose 22,050khz unless the source PCM file is lower in quality).
6.After that click ok and choose an appropriate filename, but keep the wav extension.

The above tested and worked on Windows XP with SP1 and the gsm wave file was tested on Nokia 7650 3.16 15-08-02 NHL-2NA

Below I have some screenshots of the procedure, as well as some samples to test before you try (2files-it is the same sound file encoded in PCM and GSM)

The quility is much much better than AMR.The encoded GSM wave files behave the same way standard PCM wave files.You can also set them as ringtones or message alerts.

There is also one interesting thing on the info of the codec,which describes it more and maybe why it is compatible...

"Compresses and decompresses audio data conforming to the ETSI-GSM (European Telecommunications Standards Institute-Groupe Special Mobile) recommendation 6.10"

The magic word is ETSI. I think (without any proof) that this is the standard of the gsm networks (can anyone confirm that?SIGMACOM maybe...). When we speak to the phone our voice is encoded to take less bandwidth and then it is decoded from the recipient phone (maybe that's why you can only convert to mono and not to stereo). But if this is true then every GSM phone in the world can decode such a file.
In other words the gsm encoded files may also be played on 9110,R380,9210,3650,P800,etc...

So please try the samples in every phone you can and inform...

PS:I hope I helped a lot of you people to earn some more kilobytes. My wave files are much smaller.From 530k went down to 171k.
I am also sure that it will soon come an alternative 3rd party sound recorder for the series 60 with the gsm codec or just a program that uses this,if true at least give me a credit for the discovery. Am I asking too much?

We have all the GSM ETSI specs DVD at work. I will check it there tomorrow and I will inform you in detail! 😃

That's very good Sigmacom
Thank you.

But I would also like to hear from the others. Does it work in any other phone (not only 7650s) or is it just my phone?

Besides, the quality of the compression is (a little) better that mp3 compression in 32kbps (4 kilobytes per second).

Jesus!!! The ETSI GSM Specs... It is chaos! I have isolated about 100 MBytes of zipped PDFs and binaries related to 6.10!!! It has full explanations, examples, algorithms, code, bla, bla, bla... You can make your own software or hardware transcoder with this info! (Petran, where are you???).

Anyway, I could not resolve what you asked MemphisX, because I have to study all these 100 MBytes ( 😮 ) and it will take some time... 😞
If anyone else knows something, please inform.

(Or we can just involve Petran... With this documentation, probably he can make anything... 😉 )

Thanks a lot for this info. Ive managed to get my waves down to a querter what they were before with no loss of quality.
Cheers
Stezos

HI!...

i make some tests converting WAV to WAV (GSM codec) ... but
the sound quality is not too good... is extremelly sharpness, saturated and distortioned (even if i edit the wav to a lower volume level), and i ear a "click" like a clock as background of the converted sound on the 7650 making a sound like azetat old analog long play 😃

I preffer to use short wav normal codec for some music extracts, or AMR for voice and sound effects only.. not music.

We need somebody make an App that use short Mp3 files (24, 32, 56, 96, 128 kbits. mono) like Ringtones or Alarms... that will be a cool thing! 8)

cya!

BTW!: I use Sound Forge 6.0 (from Sound Foundry) to edit sound and convert to any format.

hi!...

more tests...

no way... mp3 always win compared at any bit rate or sample rate...

GSM codec is for low quality sound... like AMR...

btw.. remeber to ear the sounds on the 7650 not on PC speakers...

gsm always make some rare noise like analog scratch... that is not ear on the PC sound...

cya!

Well, I have encoded many pcm wave files to gsm, and found on some of them (bacicly the silent ones) that it makes some clicks.

On the other side mp3 is great only if you put a bitrate above 64kbps.
I can put some samples if you want...
For my ear MP3's 32kbps are worst than gsm's 32kbps and on the pc side the real good mp3s are 192kbps and above.

Besides mp3 is not designed for low bitrates with mono sound and especially not mobile phones.

I also found that there are some more codecs that work with the 7650.
I will make some more tests and I will post them tommorow.

Have anyone tested it on any other phones?
I want to know about P800 and 9210(i)/9290...

HEY!

yeah you right at low bit rates GSM it's better thatn mp3..

but anyway i don't like the analog scratch on the 7650 with gsm codec... :-?

cya!

I just found (with google) some more info on the gsm specs and that there are also 6.20specs (but no codec guys).

http://www.networkmagazine.com/article/NMG20000517S0169
http://www.lselvon.com/science/speech.html
http://kbs.cs.tu-berlin.de/~jutta/toast.html

There are more But these are the more interesting and informative (at least for me)
Sigmacom I really apreciate the search you made but as you said, let's leave it to petran... 😃 😃 😃

OK Here is the results from the codecs testing...

COMPATIBLE CODECS WITH 7650

PCM: The standard
CCITT A-Law: Same with the PCM
CCITT U-Law: Same with the PCM
GSM 6.10: 1:5 Compression ratio,loosy compression,medium quality
IMA ADPCM: 1:2 Compression ratio,very good quality (for me it is the same with pcm)

NOT COMPATIBLE CODECS (System error message)

DSP Group TrueSpeech
Microsoft ADPCM
Ogg Vorbis (All modes)

I was offline for 2 days so I couldn't post them earlier.
So if you don't like the gsm codec you can choose the IMA ADPCM which is very good and you will also gain some space...