Voice Recording Time

I thought my 2GB Sansa Clip was supposed to record up to 69 hours of voice.  But, when I tried to record a 6 hour radio program, it required 860MB of memory!  Does anyone have a comment or had a similar experience?

There’s a different forum for Sansa Clip.

Haven’t tried, but I’m betting there’s a quality setting that let you record more at low, low quality.

There is no limitation and there is no setting to change it to a lower bit rate.  FM will record at 768kbps…pretty good quality and with good quality come large file size. 

I am surprised 6 hours used only 860MB.  I tested an older firmware and 5:49 hours was 1.87GB of memory.  Don’t feel like testing again with new firmware as it takes too long and why would anyone record radio for 6 hours.  Anyway happy FMing.

@justreboot wrote:

FM will record at 768kbps…pretty good quality and with good quality come large file size. 

It’s not good quality… it’s uncompressed quality. In fact, it’s sampled at 22kHz which is the half of CDs and most mp3 (44kHz). But you are not missing too much high frequencies because they are mainly missed in the process of FM broadcasting. Note that here I am talking about sampling rate, i.e. how many samples per second do you make from a continuous (analog) audio signal.

Why 22kHz gives 768 kbps? As each sample takes 4 bytes (16 bit stereo), it gives you 88 kBps (note the ‘B’ for byte), roughly equivalent to 768kbps (I’m missing some bits but I’m not sure were do they come from… maybe parity and stuff).

And why mp3 can be 44kHz and 128kbps (or 96, or 224, or…)? Because of compression. But in the process of reproducing an mp3 audio file 44000 (44100, actually) samples of digital audio per second have to be generated (i.e. the audio has to be decompressed).

A strong advice, if you want to keep you FM recordings, is to compress them to mp3 (or wma, or ogg…). And don’t waste too much bitrate, for 22kHz audio 96kbps should be fine (if not transparent). 

Wow…good stuff.  I think.

I did a sample Voice record and took a look at its info.

Bit rate: 384 Kbps

Sampling: 24 KHz

Resolution: 16 bits

What’s this mean…hhmm not sure but from my sample I think you will get about 10 or so hours of voice recording using a 2GB Clip.

Someone please correct me if I am wrong here.

Message Edited by JustReboot on 07-29-2008 04:34 PM

It’s not good quality… it’s uncompressed quality

What a strange statement to make. The question to ask would be - is the recording lossy or not? MP3 is hideously lossy, whereas wav is normally CD quality.

However, have Sansa created a lossy wav format - the file size would seem to indicate that? That is very important if uploading via Bit Torrent say a live concert recorded on a Sansa Clip from FM Radio.