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MP3 recordings OK at 1st but soon get crackly

Muse

Muse

Lifer
I'm using an MP3 recording utility called Sound Capture and sampling at 44 KHz off the line in on my Hercules GTXP. Recording radio and cassette playback from my receiver, I'm getting bad crackling that starts 15 to 17 seconds into the recording. Seems to be happening pretty consistently, but am still experimenting. I made a 45 minute recording and only the first 17 seconds were OK. A one minute recording of radio got crackly after 15 seconds. One recording of a minute or so was OK throughout. Any suggestions appreciated.
 


<< Try using a different recording program like Goldwave. Then use LAME to encode the mp3's. >>

Is Lame better than the other MP3 encoders? I tried another MP3 recording program yesterday, Total Recorder, the eval version. It's just the regular unregistered program, but until you register you can only record 40 seconds. Sounds OK. It doesn't provide any of it's own file compression routines either. The Sound Capture I mentioned uses the Lame encoder. Total Recorder doesn't provide the Lame encoder, but does provide Fraunhofer IIS MPEG Layer-3 Codec, Microsoft system codec and the Blade encoder. Interestingly, none of these encoders (at least as used by Total Recorder) will sample over 24,000 Hz. So I pointed Total Recorder to the Lame encoder (lame_enc.dll) that came with Sound Capture. Having done that, I could sample at much higher rates. Anyway, the sound's OK with Total Recorder. But I can't tell the difference between 24,000 Hz, 56 kbps encoding and CD Quality, with uses 30 times the HD space. I'll check out Goldwave. It looks to be about $40. Total Recorder is about $12.
 


<< Try using a different recording program like Goldwave. Then use LAME to encode the mp3's. >>

I just read your FAQ on the best MP3 decoders and why. Very interesting. I don't know what version is used by Sound Capture, but it appears to be more recent than the one I downloaded back in November. The date on the lame_enc.dll is 12/29/2001, and I assume that DLL is what the encoder is. Pointing Total Recorder to that file lets me use LAME in Total Recorder and rates up to 320 kbps, 48,000 Hz stereo. It doesn't inform me of any stuff like whether it's CBR or VBR or Joint Stereo, what version of LAME it is, as far as I can see. I have a hex editor. Maybe I can go in there an find out?
 
LAME is the best, IMO, but cracks and pops are rarely generated by the MP3 encoding, but happen during the DAE extraction to WAV. Your hardware is probably to blame, perhaps the CDrom isn't transferring steadily (you can reduce the speed or switch IDE modes) or there could be an IRQ conflict plugging up bandwidth.
 


<< The date on the lame_enc.dll is 12/29/2001, and I assume that DLL is what the encoder is. >>

Correct. There is a newer version, get it here. It was just released this past Sunday, April 14, 2002. Version 3.92.

But as richleader said, clicks or whatever don't usually get introduced during mp3 encoding - they get introduced during recording or extraction from a CD. That's why I said to try a different recorder.
 


<<

<< The date on the lame_enc.dll is 12/29/2001, and I assume that DLL is what the encoder is. >>

Correct. There is a newer version, get it here. It was just released this past Sunday, April 14, 2002. Version 3.92.

But as richleader said, clicks or whatever don't usually get introduced during mp3 encoding - they get introduced during recording or extraction from a CD. That's why I said to try a different recorder. >>

I downloaded and installed version 3.92 last night, it turns out. Yes, I noticed the _recent_ file date! I was using 3.91, the 12/29/01 version. It's nice that it's so tidy as to be usable with the presense of a single file. Total Recorder was able to use LAME encoder just by showing it the location of lame_enc.dll. I tried to point it to files under Nero, but it choked on all of them, including MP3Pro.dll, which I figured to be the one. Maybe Nero is doing something proprietary with it, but I thought I read that LAME MP3 encoding was part of Nero.

The Sound Capture developer tells me that the crackling and muddy sound I got was due to "appending" to a formerly saved MP3 file. Saving to a new file works around this problem. Obviously, saving to the same filename doesn't exactly overwrite, although you can't hear the former recording(s). Seems weird to me. Maybe it's an issue that the developer can deal with, but his tack seems to be to ask the user if they want to create a new file or use the old one (i.e. risk crackling etc. artifacts).

Can I get some suggestions on how I can sort out what bitrates to use? For one thing I don't understand the two-part bitrate scheme. For instance, ***56 kbps with 24,000 Hz*** versus ***256 kbps with 44,000 Hz*** versus ***128 kbps with 44,000 Hz***. Why are these two part? I do understand on a simple level that bigger files generally translate to better sound, but I'd like to get a handle of what's going on. Just listening to one piece of music over the radio for which I made two MP3 files (one at CD quality, actually a .wav file and the other at 56 kbps 24,000 Hz MP3 encoded using the Microsoft MP3 encoding functions, the default MP3 encoding in Total Recorder), I couldn't tell the difference on playback through some pretty good headphones. However, the .wav file was 30 times as big as the MP3. Total Recorder lets you make a choice between Stereo and Joint Stereo when using the LAME encoder, but it doesn't indicate anything about CBR versus VBR. The default is Stereo, but I figure Joint Stereo is the way to go.
 


<< Can I get some suggestions on how I can sort out what bitrates to use? For one thing I don't understand the two-part bitrate scheme. For instance, ***56 kbps with 24,000 Hz*** versus ***256 kbps with 44,000 Hz*** versus ***128 kbps with 44,000 Hz***. Why are these two part? >>

The 44,000 number means that the input signal is being sampled that many times per second. The kbps part tells you how many bits are being allocated to each sample (there's more details than that but that's the gist of it).

<< Just listening to one piece of music over the radio for which I made two MP3 files (one at CD quality, actually a .wav file and the other at 56 kbps 24,000 Hz MP3 encoded using the Microsoft MP3 encoding functions, the default MP3 encoding in Total Recorder), I couldn't tell the difference on playback through some pretty good headphones. >>

The sample rate determines the highest frequency that can be recorded - broadly speaking, the high-frequency cut-off is 1/2 the sampling rate, so the 44kHz sampling rate cuts off at about 22kHz, while 24kHz sampling cuts off at about 12kHz. And since radio only typically goes up to about 14kHz, that's why you really didn't hear much of a difference.

<< However, the .wav file was 30 times as big as the MP3. >>

That's because CD quality uses a bit rate of about 1.4 megabits per second versus your mp3's 56 kilobits per second.

<< Total Recorder lets you make a choice between Stereo and Joint Stereo when using the LAME encoder, but it doesn't indicate anything about CBR versus VBR. The default is Stereo, but I figure Joint Stereo is the way to go. >>

Use joint stereo. You'll need to use a different frontend for the LAME encoder if you want to use VBR.


 
Q]Total Recorder lets you make a choice between Stereo and Joint Stereo when using the LAME encoder, but it doesn't indicate anything about CBR versus VBR. The default is Stereo, but I figure Joint Stereo is the way to go.[/i] >>

Use joint stereo. You'll need to use a different frontend for the LAME encoder if you want to use VBR.[/i] >>

How about EAC? Does it support VBR in recording MP3s?
 


<< How about EAC? Does it support VBR in recording MP3s? >>

Yes, it does. If you get the latest version of EAC you can use its setup wizard to use LAME to encode mp3s and the best quality settings will be used automatically. EAC will put in the correct command-line parameters for the LAME encoder.

edt: you will need the .exe version of LAME rather than the .dll version. They should both come in the same .zip file, anyway.
 
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