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#111692 - 19/08/2002 00:08 Minimum MP3 bitrate for compatibility
robricc
carpal tunnel

Registered: 30/10/2000
Posts: 4931
Loc: New Jersey, USA
Say I have an Audible.com file that I want to make into an MP3. It's just spoken word, so a low bitrate is not noticed and saves space. What is your opinion on what bitrate is as low as you can go without sacrificing compatibility with older MP3 devices?
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-Rob Riccardelli
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#111693 - 19/08/2002 04:49 Re: Minimum MP3 bitrate for compatibility [Re: robricc]
pgrzelak
carpal tunnel

Registered: 15/08/2000
Posts: 4859
Loc: New Jersey, USA
Greetings!

Unless audible has changed, their files are encoded with some protection or other non-MP1 layer 3 format. You will need to convert them in order to get them to play on the empeg. You can use the Total Recorder software to capture from your soundcard, or you can use the audio editor GoldWave that can open the .AA files from audible directly and save them to a more friendly format.

In either case, unless you can download direct to public MP3 format (you couldn't as of a few months ago with my last download from there), you will need to cross-convert. Go for the best quality you can from Audible, and then scale down on your machine to the quality you prefer.

Note: I know that Doug (tanstaafl) has been having trouble with very low bitrate files - perhaps he has found the breakpoint...
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Paul Grzelak
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#111694 - 19/08/2002 04:56 Re: Minimum MP3 bitrate for compatibility [Re: pgrzelak]
robricc
carpal tunnel

Registered: 30/10/2000
Posts: 4931
Loc: New Jersey, USA
Audible allows you to burn most stuff to CD. I simply made 96kbps MP3s using EAC and LAME.

I have a friend that had trouble playing really low files with Winamp 1.92 (I think). He uses it because it can run as an executable without installing....obviously a very paranoid individual. All books I got from audible are free downloads, so giving him a copy as MP3 doesn't sound wrong to me.

He uses dialup, so keeping the bitrate small is ideal. We just have to find the smallest file size that is still compatible with version 1.x Winamp, his DVD player, and Intel PocketConcert.


Edited by robricc (19/08/2002 05:07)
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-Rob Riccardelli
80GB 16MB MK2 090000736

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#111695 - 19/08/2002 05:16 Re: Minimum MP3 bitrate for compatibility [Re: robricc]
pgrzelak
carpal tunnel

Registered: 15/08/2000
Posts: 4859
Loc: New Jersey, USA
Greetings!

Have you had any trouble with the CDs you burned from Audible? Every test one I have done has what sounds like track sync problems with the last few tracks on the disk. Thus my quest for finding a way that didn't involve creating coasters...

I don't think you start running into trouble with MP3 cross platform until you get below the 96kbps range. I strongly recommend CBR in this case, again for compatability only. I assume you are already converting to mono as well.
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Paul Grzelak
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#111696 - 19/08/2002 05:36 Re: Minimum MP3 bitrate for compatibility [Re: pgrzelak]
robricc
carpal tunnel

Registered: 30/10/2000
Posts: 4931
Loc: New Jersey, USA
The CDs I've made have all been good. I have a Lite-On 16x IDE burner at home and 12x at work. Both have made good CDs.

Some MP3s have been joint stereo and some mono. For my personal use, I could care less about a 96kbps vs 16kbps. The only problem is when I have to send an MP3 to someone living in the dark ages with Winamp 1 and 56k.

PS- 16kbps files definitely do not work.
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-Rob Riccardelli
80GB 16MB MK2 090000736

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#111697 - 19/08/2002 06:05 Re: Minimum MP3 bitrate for compatibility [Re: robricc]
peter
carpal tunnel

Registered: 13/07/2000
Posts: 4180
Loc: Cambridge, England
16kbps files definitely do not work.

MPEG-1 layer 3 defines bitrates from 32kbits/s to 320kbits/s. Any bitrate below 32kbits/s has to be encoded as MPEG-2 (or Fraunhofer's "MPEG 2.5").

Perhaps "sufficiently old" decoders only grok MPEG-1, not MPEG-2 (the data formats are the same, just the frame headers are different). http://www.iis.fhg.de/amm/techinf/faq.html

So in summary, try not going below 32kbits/s (or, for similar reasons, 16kHz sampling).

Peter

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#111698 - 19/08/2002 06:16 Re: Minimum MP3 bitrate for compatibility [Re: robricc]
peter
carpal tunnel

Registered: 13/07/2000
Posts: 4180
Loc: Cambridge, England
Winamp 1.92 (I think). He uses it because it can run as an executable without installing....obviously a very paranoid individual.

Obviously an individual who appreciates well-behaved Windows programs. If he were paranoid, he'd be building everything from bootsector onwards from source tarballs -- not that that is necessarily enough to be sure...

Peter

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#111699 - 19/08/2002 06:18 Re: Minimum MP3 bitrate for compatibility [Re: pgrzelak]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12338
Loc: Sterling, VA
Can't you just use any sound recording program? Heck, the "sound recorder" that comes with windows should be enough, shouldn't it? Yeah it's slower than burning CDs since it's real time, but it would work, wouldn't it? You just have to select the correct input in the volume controls.
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#111700 - 19/08/2002 06:20 Re: Minimum MP3 bitrate for compatibility [Re: robricc]
genixia
Carpal Tunnel

Registered: 08/02/2002
Posts: 3411
Peter's given you the theoretical value - but it's going to be time-consuming to test that for compatibility with a wide range of devices. Practically speaking, 56kbps CBR was the early 'standard' in the dark ages of limited bandwidth and storage, so it should be a safe bet compatibility-wise.
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#111701 - 19/08/2002 06:21 Re: Minimum MP3 bitrate for compatibility [Re: peter]
robricc
carpal tunnel

Registered: 30/10/2000
Posts: 4931
Loc: New Jersey, USA
Obviously an individual who appreciates well-behaved Windows programs.

His main gripe with new versions of Winamp is that the installer puts an AOL shortcut on the desktop. Hence, he only uses the version that runs as a single executable. Paranoid.
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-Rob Riccardelli
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#111702 - 19/08/2002 07:00 Re: Minimum MP3 bitrate for compatibility [Re: robricc]
Roger
carpal tunnel

Registered: 18/01/2000
Posts: 5683
Loc: London, UK
...installer puts an AOL shortcut...

It didn't do this when I installed Winamp 3 last week.
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#111703 - 19/08/2002 07:04 Re: Minimum MP3 bitrate for compatibility [Re: Dignan]
pgrzelak
carpal tunnel

Registered: 15/08/2000
Posts: 4859
Loc: New Jersey, USA
Greetings!

Certainly it would work, but I usually wind up getting a few books at a time. When I did this last, I burned them to CD and ended up with about 45 CDRs worth. I would prefer not doing that in real time...
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Paul Grzelak
200GB with 48MB RAM, Illuminated Buttons and Digital Outputs

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#111704 - 19/08/2002 08:36 Re: Minimum MP3 bitrate for compatibility [Re: Roger]
robricc
carpal tunnel

Registered: 30/10/2000
Posts: 4931
Loc: New Jersey, USA
If there is an existing install of winamp on your machine, you can uncheck the shortcut during install. If there is no current version, you have no choice. At least that's how it's handled in 2.80.
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-Rob Riccardelli
80GB 16MB MK2 090000736

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#111705 - 19/08/2002 09:32 Re: Minimum MP3 bitrate for compatibility [Re: robricc]
wfaulk
carpal tunnel

Registered: 25/12/2000
Posts: 16706
Loc: Raleigh, NC US
How about using FreeAmp/zinf?
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Bitt Faulk

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#111706 - 19/08/2002 09:36 Re: Minimum MP3 bitrate for compatibility [Re: wfaulk]
robricc
carpal tunnel

Registered: 30/10/2000
Posts: 4931
Loc: New Jersey, USA
Good idea. A free MP3 app that's not owned by AOL and is not bloated like Sonique. That probably solves the computer use.

However, I will have to make bigger MP3s anyway so they will also work with the Intel player and the DVD player.
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-Rob Riccardelli
80GB 16MB MK2 090000736

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#111707 - 19/08/2002 10:02 Re: Minimum MP3 bitrate for compatibility [Re: robricc]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31596
Loc: Seattle, WA
Yeah, I've done the Audible->TotalRecorder->MP3 trick recently, and it worked.

The only problem is that the one thing that would make it useful to me, the "acceleration" feature, didn't work for me with their player client. So I was only able to do the file-conversion in realtime. Now THAT is a pain.
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