digitalization
Printed From: FSI Language Courses
Category: Learning Languages
Forum Name: General Discussion
Forum Discription: Discussion about studying languages using the FSI courses. If you would like to see a specific language forum not listed below, just let us know.
URL: http://fsi-language-courses.com/forum/forum_posts.asp?TID=75
Printed Date: 16 January 2009 at 3:25am
Topic: digitalization
Posted By: awb1989
Subject: digitalization
Date Posted: 11 July 2006 at 7:37am
sorry, i'm not really sure which forum to put this in, or if it even fits in here at all... but i'm wondering about the process you use to digitalize the audio? I'm interested in digitalizing a danish audio course I have, but it can be only for personal use, it's not FSI, so I unfortunately can't share it online or anything..... but i'm still curious about how to digitalize it for personal use. thanks
|
Replies:
Posted By: gdfellows
Date Posted: 11 July 2006 at 5:51pm
I have a stereo cassette deck connected to the input of my computer sound card. I use Sony Sound Forge Audio Studio for the digitizing and processing. It will create an audio file from whatever sound source is playing through the sound card.
|
Posted By: bamboo
Date Posted: 11 July 2006 at 9:58pm
As an alternative for digitizing audio is the software Audacity. It is open sourced freeware and can be downloaded from http://audacity.sourceforge.net/ - http://audacity.sourceforge.net/ . I've used it to digitize all my language cassette tapes. It support multiple operating systems and multiple audio formats. For mp3, it uses the lame mp3 codec.
For editing the mp3 tags, I've used The Godfather http://users.otenet.gr/~jtcliper/tgf/ - http://users.otenet.gr/~jtcliper/tgf/ which is freeware.
|
Posted By: TheBigZaboon
Date Posted: 06 August 2006 at 11:07pm
bamboo,
Will Audacity convert from CD audio format to mp3? I downloaded a copy after reading your post. I understand that you use it to convert tapes to mp3, but will it convert CD audio as well?
Thanks.
|
Posted By: Sir Nigel
Date Posted: 08 August 2006 at 3:29pm
I'm not too sure, but I use http://www.quinnware.com/ - Quintessential Player and it will convert CDs to either .wav or .mp3 for free.
------------- Insurance Excuse:
The accident was due to the road bending.
|
Posted By: TheBigZaboon
Date Posted: 08 August 2006 at 10:06pm
Sir Nigel,
Thanks for the reply, and the advice.
I think I have answered my own question: I tried Audacity with a CD, and it informed me that it does not read from audio CDs. It also told me that I have to find a ripper to read from a CD. I will be trying it later today, or later in the week, attempting to digitize from tapes to mp3. After that, I will try the software recommended by Sir Nigel to copy from CDs to disk, and then to mp3.
Thanks again.
TBZ
|
Posted By: BookCat
Date Posted: 21 August 2006 at 3:55pm
If you have a Mac, Amadeus II works really well. It has quite a few options as to format, too, including MP3.
HTH
|
Posted By: r438
Date Posted: 03 September 2006 at 1:44pm
I'm starting the digitalization of Saudi Arabic. Any suggestions for removing the tape hiss in the background? I have a cassette deck connected to my sound card, and read in with Audacity. I'm reading where the volume-in is as high as possible without clipping it.
However, there is some white noise (tape hiss). I compared to some of the other recordings. There is virtually no background noise in French 13.1 or German 3.1, and there is slightly less than mine in Turkish 31. Any suggestions for how to remove this hiss?
I tried the Noise removal in Audacity, and it really zeroes out the white noise, but I don't really like how it distorts the speech. I've also tried playing with a low-pass filter set at 8 kHz, but I don't really hear an improvement. How exactly were the French and German tapes recorded?
If I can't improve this, I'll probably just leave the tape hiss in, as it's not terribly distracting.
|
Posted By: KayElleEm
Date Posted: 03 September 2006 at 3:13pm
I don't know if it's worth $14.99 to you, but I use http://www.microsoft.com/windows/plus/dme/Music.asp#analog - Microsoft's Analog Recorder . It's specifically designed for cleaning up the hiss from cassettes and vinyl records. I think it does a pretty good job. You can listen to the Standard Chinese mp3s (Units 5 and 6) to see if that's the quality you want.
|
Posted By: r438
Date Posted: 04 September 2006 at 9:20pm
thanks - that's for xp, but I'll see if there's a W2K equivalent. If not, it seems to reduce the hiss a little if I run it twice through a low pass filter at 4500 Hz, so maybe that's what I'll stick with.
Also, anyone know what dpi setting the other pdfs were scanned at? If I scan at 300 dpi, each page is about 64 KB, much larger than the size of the other documents (German for example is about 10 KB per page. I'm tempted to just try to OCR the thing and edit.
|
Posted By: gdfellows
Date Posted: 04 September 2006 at 9:31pm
Originally posted by r438
Also, anyone know what dpi setting the other pdfs were scanned at? |
I've scanned all PDFs here at 300 dpi. I do use the "reduce file size" option in Adobe Acrobat.
|
Posted By: DemiPuppet
Date Posted: 05 September 2006 at 9:55pm
I think a sharp lowpass filter at 8Khz is best, otherwise some of the sibilants will get lost.
http://en.wikipedia.org/wiki/Sibilant - http://en.wikipedia.org/wiki/Sibilant
If the recording is in stereo, make sure it's converted to mono. This will reduce the hiss by a few dB.
If the recording is really miserable, you could try using an expander. For example, some of the Turkish tapes were recorded at a really low audio level. In order to pull the sound out of the hiss, I would amplify only the audio with an amplitude greater than the hiss level.
- Using Audacity, sweep out a couple of second of non-speaking hiss on the timeline.
- Select "Analyze|Plot Spectrum
- Note the audio amplitude in dB's around 4000 Hz
- Determine how much the audio can be amplified without clipping.
- Amplify the audio that is louder than the value found in step 3.
I use the "normalize" commandline program and the "-n" option for step 4 and the "sox" command line program and the "compand" option for step 5.
http://normalize.nongnu.org/ - http://normalize.nongnu.org/ http://sox.sourceforge.net/ - http://sox.sourceforge.net/
Since the Turkish 2, Vietnamese, and Swedish tapes weren't too bad sounding, I didn't perform this step on them. Probably should have.
|
Posted By: Sir Nigel
Date Posted: 06 September 2006 at 9:09am
DemiPuppet, how would converting to mono alone reduce hiss? Is it by perception only?
Obviously stereo is pointless for all FSI courses, but I would imagine the "rubbish in, rubbish out" rule would apply unless you're using a noise reduction plug-in.
Originally posted by gdfellows
I've scanned all PDFs here at 300 dpi. I do use the "reduce file size" option in Adobe Acrobat. |
In addition I've saved my PDFs using JPEG 2000 and the file size is tremendously lower than regular PDFs.
------------- Insurance Excuse:
The accident was due to the road bending.
|
Posted By: DemiPuppet
Date Posted: 06 September 2006 at 10:15pm
The assumption is that the hiss is in each channel is totally random while the desired signal is nearly identical. So when the left and right channels are added together, the total "good" signal is doubled (+6dB). But since the noise is random, sometimes it adds together and sometimes it subtracts. Totally random noise will add as a "Root Mean Sum" and only increase by 3dB.
When converting to mono, the two stereo channel signals are summed together and then divided by 2 (in other words reduced by 6dB). So now the mono "good" signal is back to it's original level, but the hiss is reduced by 3dB. The hiss amplitude will be reduced to ~0.707 of its original value.
As a bonus, going to mono means that the precious bits used by the MP3 encoder can be dedicated to just one channel rather than being wasted trying to also encode the differences between the channels. I suspect the original recodings were all in mono anyway.
One additional way to maximize the use of the MP3 bits is to filter out all the high frequencies (>8Khz) and then downsample to 22050 Hz. According to the Nyquist-Shannon's sampling theorem, the sampling rate needs to be only twice the highest signal frequency in order to perfectly reproduce the sound. By reducing the number of samples, less MP3 bits are needed to produce the same quality of signal. Of course you could keep the same MP3 bit rate and thus improve the quality. I know it seems odd that reducing the sampling rate would actually improve the final signal quality, but it's true.
I use the SOX command line program to do the resampling after filtering out the high frequencies.
|
|