Saved mp3 files lose sound quaility

[goat-roper]

I would like to know how to edit a music mp3 file and then save it in mp3 without losing quality and sound? I have downloaded several mp3's from YouTube using us.onlinevideoconverter.com/. After I've edited them (shorten or lengthen) I notice the sound quality has gone down along with the new-saved file size!

Using a Dell laptop running XP Windows.

[kozikowski]

The reason we tell people not to do production in MP3.

You can export the new MP3 in 320 quality. That should sound pretty much exactly normal. You can also export as an uncompressed file format like WAV or AIFF. What you can't do is export the same file size as before. MP3 compression damage and distortion increases every time you make a new one and you can't stop it.

You can do simple edits with a pure MP3 editing program like MP3Split. Simple edits like cutting and overall volume control don't need re-compression.

Audacity always makes a new MP3 and you can't stop that, either.

Koz

[steve]

Encoding as MP3 always loses sound quality.
To be able to do all the things that it does, Audacity operates on "uncompressed" audio data. This means that the MP3 has to be decoded. If it is then exported as an MP3 file, then it has to be re-encoded and that will lower the sound quality.

Depending on the MP3 settings, the amount of damage can be limited. Using a high bit rate for the MP3 will cause less damage than using a low bit rate, but the file size will be larger.

The only ways to prevent any loss of sound quality are either to export in an uncompressed format such as WAV (the file size will be very much bigger than an MP3), or to use a program that can edit MP3s without decoding them first. MP3Split is a free open source program that can edit MP3s without decoding them. It is only able to do basic editing tasks like splitting or trimming tracks, but there is no loss of sound quality. Another one is MP3DirectCut

[goat-roper]

kozikowski: Only place I see 320 is under Bit Rate which is now set at 64. Is this where it should be set at 320?

kozikowski and Steve: Here's what is set now under Preferences:

in Quality:
What is the best setting for each of these 6 areas?

in File Formats
under MP3 Export Setup:
Bit Rate <what number is best to use (320?) - now set at 64>

in Spectrograms:
FFT Size <what # - now at 4096
Max. Frequency set at 8000

in Interface:
what dB should be used

Is there any other place I should be checking out also?

Thanks for what you guys have already helped me with and in advance for any info to come. Please keep in mind I am NOT a professional - just editing music for my own use; a hobbyist I guess you'd say!

And I am going to work with the two other programs Steve mentioned - to see IF I can get one of them to work for me!!

Glenn

[steve]

320 kbps is the highest possible sound quality for MP3, but it also produces the biggest files.
64 kbps is low quality, suitable for speech when you want small files, but there will be noticeable loss in quality for stereo music.
128 kbps is usually considered the minimum for reasonable quality stereo music, but higher settings are often noticeably better.

Audacity 1.3.13 also offers the option of VBR encoded MP3s. For settings below 320 kbps, VBR gives better sound quality for a similar file size.

in Spectrograms:
FFT Size <what # - now at 4096
Max. Frequency set at 8000

This does not affect sound quality.
If you have a reasonably modern computer I'd suggest setting it to 1024.

in Interface:
what dB should be used

This does not affect sound quality.
The best setting for this depends on what you are doing. See here for an explanation of what it does: http://manual.audacityteam.org/man/Inte ... references

You have posted in the Audacity 1.2.x part of the forum but I suspect that you are not actually using that version. Please check which version you are using so that we can give relevant responses to your questions (Help menu > About Audacity)

[goat-roper]

Steve,

Thanks for the reply. The Audacity version I'm using states it's 1.2.6

[steve]

As you're using MP3 format it would be worth upgrading to Audacity 1.3.13 as this will allow you to use VBR encoding which gives better sound quality for similar file size than CBR encoding that is used in Audacity 1.2.x.
If you want to try it, you can install Audacity 1.3.13 alongside your current version.

Audacity 1.3.x can open projects saved by Audacity 1.2.x, but not the other way round.
The MP3 encoding options are in the Export dialogue options http://manual.audacityteam.org/man/MP3_Export_Options