MP3 Recorders? 37
ilbrec asks: "A friend of mine is a field biologist who studies frog calls. Recently when I was talking with him, he was interested in a MP3 recorder for his research use so that he can record the frog calls and analyze the sound on his computer later on. No, he does not care for DAT at all. He has one himself that he has so much trouble with. He is looking for a small device that takes at least 64 MB or so of solid-state removable memory that is easy to use. Sound recording quality does not have to be great, as frog calls can easily be analyzed at 96 kbps, according to him. No, he does not care for DAT at all. Does anybody know a good one?" Well, we have embedded devices that can playback MP3s...why not ones that can record live audio and use CompactFlash (or Smartmedia) cards, instead of the old cassette?
Why not MiniDisc? (Score:2)
- A.P.
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* CmdrTaco is an idiot.
Re:Why MP3? (Score:1)
Re:MP3 compression is too slow (Score:1)
-Andy
Re:MP3 compression is too slow (Score:2)
Even though the DSP may have been there it would have made the player too power-hungry.
-Andy
Why MP3? (Score:3)
Lossy compression for scientific research? (Score:2)
Re:Analysis (Score:1)
It's the conspiracy (Score:3)
It seems plausible, but does anybody have facts to back it up?
Has your friend tried DAT? (Score:1)
Re:bottleneck is probably the compression (Score:2)
This is exactly the sort of task a DSP or IC kicks a general CPU's ass at.
Re:bottleneck is probably the compression (Score:2)
I'd say that the biggest problem with doing direct to mp3 recording is going to be getting the power to do real time compressions and getting it small and low powered. For now I'd stick with minidisks, they're cheap, small and fast.
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MP3 compression is too slow (Score:2)
That's why CDs use raw audio, incidentally: audio compression was well understood at the time, but needed more computational power than was available in audio systems at the time.
Re:MP3 compression is too slow (Score:1)
Minidisc is not appropriate (Score:1)
Re:AIWA has one (Score:1)
AIWA has one (Score:1)
Re:MP3 compression is too slow (Score:2)
bottleneck is probably the compression (Score:2)
It seems on the face of it that the thing keeping an embedded device from recording straight to mp3 would be the cpu required to do so. I'm basing this on the amount of time it takes my p2-450 equivalent machine to encode from .wav (uncompressed sound, basically what you're friend would be getting) to .mp3. Of course, yes, I'm going to 128+kbps, but still, there is only so much cpu you can cram into a portable the size of a pack of cigs.
Naturally take my suspicious as to the unfeasibility of this with a grain of salt as I'm just a sysadmin/desktop/server-type person, not an embedded hardware designer (maybe there is some uber-l33t way of using a custom chip to do this). I'd have to cast my vote for minidisc too, it sounds quite nice (a friend of mine uses his portable MD recorder/player to sample stuff for his electronica band).
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Fuck Censorship.
Re:bottleneck is probably the compression (Score:2)
No, I'd guestimate that it takes about 6-8 minutes to encode a 5 minute track on my machine. So I'm not quite to the real-time level yet. Partially I think this is because the FPU on my proc (a celeron 300a that's been running @ 464 for about 18 months now) isn't as good as a normal p2 and it's cache isn't as big. :-) But it was cheeeep, and that's real good if you're a po' college student.
My point was that it would take a pretty powerful CPU to encode to mp3 in real time. Namely a cpu you aren't likely to find in an embedded device due to cost, power, thermal, and space constraints...
yes, anyone can encode to mp3 given patience, but the problem is that data collection has to be in real-time (i.e. you can't tell the frog to shut up for a sec while your recorder chugs away...).
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Fuck Censorship.
Re:MP3 recorders will never exist - WRONG!See (Score:1)
Re:do slashdogs ALWAYS reply without reading links (Score:1)
As for the 32kbps that is not ridiculous. That is what is built into the Nomad. What is ridiculous is your assumption that I am a "slashdog" and couldnt read the specifications required by the person after he stated that he needed 96kbps. Why you jumped to the conclusion that I would have suggested that the Nomad (with only a puny builtin mic and no analog or mic input) would be suitable for this persons purposes - I really don't know ?
I hoped to bring something more to the discussion than this sort of flame exchange. I thought the information regarding this chip might be of interest. However, next time i dash off a post to /. before running off for an appointment I'll try make and sure I dont generate this ill-tempered response from my (seemingly) poorly and hastily chosen words.
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Incidentally a friend of mine several years ago recorded deer dialect across several regions of the British Isles and Europe and did computer based voice analysis of the regional differences. It's a small world isnt it...?
Re:MP3 Recorders? How about Minidisc? (Score:1)
Louis Wu
"One of life's hardest lessons is that life's lessons are hard to learn."
Nomad (Score:1)
Re:AIWA has one (Score:1)
According to the spec table on that same web page: Recording with a built-in microphone: MP3/bit rate: 16Kbps/sampling frequency: 16 KHz
The biologist asked for 96Kbps minimum for recording the frog calls.
Re:Some available MP3 and digital voice recorders (Score:1)
http://www.dataplay.com/
MP3 Recorders? How about Minidisc? (Score:2)
How about Minidisc player/recorders? They have optical out...you could either get an optical->analog converter, or get a sound card which accepts optical link cables.
mp3 is probably a bad idea (Score:2)
Of course, I am assuming he has a microphone with a frequency response > 20kHz in the first place.
I don't know why he hates DAT, but there are some CD-R decks out there now.. That's about it for him, though.
wishus
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How about Creative Nomad Jukebox? (Score:1)
This thing is able to record to WAV files on internal HDD (6G, upgradeble to 20G), and has various quality settings (sapmle rate, bits per sample), so the file size can be much reduced if you care about space more than quality.
The only major low point is battery life (it would eat 4 AAs in about 3 hours or less). But it takes in 12V DC, so if I were him, I'd supplement it with something like small lead-acid battery (like one used in motorcycles) - and sure it'd handle all-night field recording sessions with no problem.
I own this thing and it really rocks.
Analysis (Score:1)
just my $.02
MiniDisc (Score:1)
It can store 74 minutes of high-quality stereo on a 2.5" disc, housed in a protective cover. the media is cheap and you can get it anywhere, no need to buy expensive flash cards.
when recording in mono on a standard recodring walkman, the recodring time is doubled. the newer models from Sony [64.14.40.118] can recodr up to 320 minutes in MDLP mode on one disc, check out the MZ-R900 [minidisco.com] on Minidisco.
i've had a MZ-R50 for many years now, and it's still going strong, they are built to last.
it's a sony...
Verbing Weirds Language.
Laptop maybe the best way to go. (Score:1)
Taking all this into consideration I believe that your best bet would to simply use a laptop (many of which can work when closed), to do your recording. I found an old IBM Thinkpad 486/75MHz (sales on E-bay for $200) that can to simple real-time hard drive recording. A 1G hard drive could hold 4 hours or more of mono sound depending on the sample rate. There also embedded device "mother boards" that run Linux which are about 3" X 3".
I installed a striped down version of Linux/GNU to setup a no-frills text based computer that can handle the job. Using the lap-tops internal ADC (analog to digital converter) will pickup some electronic noise from inside the computer. But I was able to keep this to a minimum by using an external amplified microphone. The best thing would be to use an external ADC which connects to a USB port that sells for $300.
As far a recording software that works on Linux, you are pretty limited. I was able to hack together a script that utilized "arecord" (a CLI program produced by the ALSA project). My real project is to create a GPL program which I call Manauton, which stands for manual and autonomous recording. This program would determine when to save a sound to disk using some sort of trigger. The trigger could be a manual button press or it could be a sound trigger, hence manual or autonomous. The program also uses caching so the sound just prior to the trigger can be captured.
If you are interested in my Manauton project feel free to e-mail me.
Re:MP3 Recorders? How about Minidisc? (Score:2)
Yeah© I've got to go with a recommendation for minidisc recorders too:
1© The media's alot cheaper, ¥unless you have a laptop handy to download all the mp3's too©
2© They're about the same size as mp3 players / recorders© which is alot smaller than the dat recorders I've seen© ¥is size his issue? DAT is really good on other counts©©© :
3© I don't want to start a war here, but minidisc recordings ¥ATRAC-3 are higher quality than most ¥though, truely, not all mp3s©
4© Minidisc recorders with good solid state buffers ¥most have 40 second buffers, are as close to solid state as you probably need to get, if rough terrain is an issue©
5© And despite what 'vraptor' said, you don't need an optical link to get the sound out of the minidisc recorder© It's better, of course, if you can keep your D->A->D chaining minimal, but almost every minidisc player has an analog out line© ¥For headphones, if nothing else
Hope that helps!
-Andrew
Larger solution? (Score:1)
What I am thinking of is using a wearable device. You wont get super high quality but as you say nothing to fancy is required. The hard part comes from the fact that wearables are still mostly a hobbiest project. The hardware is easily obtainable and getting linux installed and running on a wearable has also been achieved. After that point the challenge is no longer hardware but software. I've looked a bit for mp3 recorders and found none. With minimalistic (nothing on the scale required) I haven't attempted to make one either. But from people I have discussed with it is seemingly possible. Buffer the sound and encode it. Depending on the hardware you could have 100 to 933Mhz at your disposal. My old AMD K6-550 with a heavy load was encoding at a bit over twice the speed so I further believe it can be done.
Along with extended mp3 recording ability (assuming it can be done) he could also set it up for in the field data entry. Of course you still come to the usual problems Wearable hobbyists run into, a display, and battery power.
(Wearable of course is a "wearable computer" compact, light, low power, for those not in the know)
It aint no hand held 64mb AA operated device, but it could be done I say.
I should have previewed.... (Score:1)
And the k6-2 550 was a desktop box.
do slashdogs ALWAYS reply without reading links? (Score:2)
As for your assertion that the Nomad will record voice at 32 kbps, that is just plain ridiculous. You can get better fidelity than a 32k mp3 with a knitting needle and a wax record on a hot day. The question specifically states that the biologist needs at least 96kbps, and I'm willing to bet that the "built-in mic" is going to be horribly inadequate as well.
If there is a hi-fidelity MP3 recorder that allows ordinary consumers to produce non-watermarked mp3s and transfer them to computer within the next year, I will publically recant. However, there is no chance of this. Read the cryptome article if you don't believe me.
MP3 recorders will never exist (Score:3)
Some available MP3 and digital voice recorders (Score:1)
Some that I've come across:
- Sensory Science MP3 players/recorders with built-in microphones [sensoryscience.com]
- Samsung YP-E32 and E64 [samsungusa.com]
- Olympus and other manufacturers also have Digital Voice Recorders that can download to PCs (albeit with unspecified file formats)
There are bound to be more offerings out there, but they all do seem a bit vague on the recording format.