help trying to fix mp3 files

[jacm1964]

Hi,

I am trying to use audacity 2.0.

I am trying to use the apply chains. I am trying small samples to see if it will work. Ran into problem right of the bat. Audacity will open my mp3's in 22050 sample rate, so when I am in the chains, I keep getting a prompt

Invalid sample rate

resample

the proiect rate (22050) & bit rate (320 kbps) combination is not supprted by the MP3 file format. You may resample to one of the rates below.

I have to manually change to 44100.

I would like to change the 22050 to 44100.

It is when you open Audacity but if I hit apply chains or open Audacity opens it 22050.

Please help.

Mark

[kozikowski]

You can change the Audacity default specifications in preferences.

Audacity > Edit > Preferences > Quality. Stereo/Mono is set in Devices.

Koz

[jacm1964]

Koz

Thanks for the quick response.

Not sure I understand, in preferences, devices, interface, I have tried MME & now the only other choice, Windows Direct Sound, primary sound driver, have tried the only other choice of my realtek stereo speakers, channels are on stereo.


quality is on 44100hz as default, 32 bit float, high quality sync, dither = none, high quality sync, dither = shaped

Hope that helps, I open audacity 2.0.0. I hit apply chain. Audacity start but as soon as it open the 1st song it is changing from 44100hz to 22050hz.

Mark

[kozikowski]

We have to cover the bases.

The purpose of Chains is to automate repetitive tasks. Can you make a good recording without Chains?

Koz

[jacm1964]

I am sorry, I don't understand your question.

I want to change the way audacity is opening my mp3's.

It open them up @ 22050, it will work on, I am not sure of the range, but it works on 128 bitrate, when it gets some @ 48, that is when I get promted, & this continues.

I guess my question is the songs below 128 not worth saying?

If so that is fine.

mark

[kozikowski]

Audacity opens sound files at the rate they were recorded. I'm struggling with a small, hand-held recorder that produces files at 32000, not 44100. I/We can change it by moving the little rate window at the lower left, but I don't know any way to do that in Chains.

Koz

[kozikowski]

Audacity uses a bitrate of 128 as its stereo compression default. It works OK. It works super well if the show is mono. The break point for stereo is 64 and mono is 32. Below those numbers the sound is always pretty awful.

That's assuming a perfect WAV or AIFF or original production or show.

If you are opening and editing existing compressed files, then the problem is much more serious. The quality is always going to be worse than the original unless you Export the work in uncompressed form such as WAV. You can fudge by using a really high MP3 rate like Stereo 256 or higher. In all cases the file sizes are going to be larger than the original.

This is why we say never do production in MP3. The sound quality almost always takes a hit, or if it doesn't, the file sizes are going up. Or both.

If you have a collection of files that vary in compression, sample rate and bitrate — and possibly quality and volume, this doesn't seem to me to be a job for Chains. Chains works well when all the songs are the same or have the same specifications, etc.

You have a "by hand" curating job.

Koz

[jacm1964]

Koz:


Again thank you for you time.

I understand more now. I will have to do them manually &/or re-download them.

I appreciate your patience w/my lack of knowledge.

[Gale Andrews]

We ought to improve that so you don't get asked questions when processing a Chain.

Do you want to vote that Chains has a Sample Rate choice for the ExportMP3 command? We would probably have a Bit Rate choice too, and Chains would either not let you set an invalid sample rate/bit rate combination, or would give a sample rate option that was "highest possible" (for the chosen bit rate).

As it is now, here are the valid sample rate / bit rate combinations for MP3:

Code: Select all

MPEG-1 layer III sample frequencies (kHz): 32 48 44.1:
bit rates (kbps): 32 40 48 56 64 80 96 112 128 160 192 224 256 320

MPEG-2 layer III sample frequencies (kHz): 16 24 22.05:
bit rates (kbps): 8 16 24 32 40 48 56 64 80 96 112 128 144 160

MPEG-2.5 layer III sample frequencies (kHz): 8 12 11.025:
bit rates (kbps): 8 16 24 32 40 48 56 64 80 96 112 128 144 160 

As you can see, the highest bit rate that will work with any sample rate is 160 kbps so one answer is to set the MP3 Export Options to 160 kbps.

What effects are in your Chain? You should not do amplitude adjustments, cuts and pastes on MP3's in Audacity, because Audacity will always re-encode the MP3 causing it to lose quality. You should do those type of edits in direct MP3 editors that don't need to re-encode. See http://wiki.audacityteam.org/wiki/Lame_ ... tion#lossy .

And by the way you should update Audacity to the latest 2.0.5 from http://audacityteam.org/download/windows .



Gale