MP3 speed or compression ?

Audacity Help Forum Windows
1

I load mp3 files all of the time. Mostly speaking , not music.

Trim them down a bit, increase volume and then save them.

Do it all the time…

Once obout 2 weeks ago I had one (and it noted that it was at a certain speed) so when I loaded it in
sure enough sounded like a chipmunks talking…
I changed some of the setting under the “effect” (don’t remember which one" pull down and got it
so it was somewhat normal.

In any case, what would cause this ?
are there some settings or adjustments that I can make when importing the file ?
If not what can I do after its loaded ?

p.s. when I listen to the file in winamp, or windows media player it sounds fine

2

If you can post the mp3 file that does this, I am sure the developers would be interested.

3

There is a [u]Playback Speed Toolbar[/u] but it has it’s own-separate “play” button and the regular play button should work normally.

p.s. when I listen to the file in winamp, or windows media player it sounds fin

Occasionally, we’ll see “bad” MP3s that play OK in other software but Audacity can’t open them. But I’ve never heard of this symptom.

There is a program called [u]MP3directCut[/u] that can do limited editing without decompressing the MP3.

…When you open an MP3 a regular audio editor it gets decompressed. Then if you re-export as MP3 you are going through another generation of lossy compression and some “damage” does accumulate. You may not hear any quality loss but it’s something you should be aware of and you should try to minimize the number of times it’s re-compressed.

4

As mentioned, it plays in 3 different audio utilities Winamp etc…

So it’s not damaged/broke in that sense.
There must be something that Audacity detects that changes it.

i.e. the play time is 8hrs , in audacity it’s 30 min. long

5

Please let us know what this online tool says about that file: https://mediaarea.net/MediaInfoOnline

6

will retry

7

General
Complete name : the_war_of_civilization.mp3
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42 (isom/mp42)
File size : 578 MiB
Duration : 8 h 6 min
Overall bit rate mode : Variable
Overall bit rate : 166 kb/s
Encoded date : UTC 2020-05-07 09:47:21
Tagged date : UTC 2020-05-07 09:47:21
Writing application : Google
gsst : 0
gstd : 29206059
FileExtension_Invalid : braw mov mp4 m4v m4a m4b m4p m4r 3ga 3gpa 3gpp 3gp 3gpp2 3g2 k3g jpm jpx mqv ismv isma ismt f4a f4b f4v

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L3.1
Format settings : CABAC / 3 Ref Frames
Format settings, CABAC : Yes
Format settings, Reference frames : 3 frames
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 8 h 6 min
Bit rate : 67.9 kb/s
Width : 1 280 pixels
Height : 720 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 6.000 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.012
Stream size : 236 MiB (41%)
Title : ISO Media file produced by Google Inc. Created on: 05/07/2020.
Encoded date : UTC 2020-05-07 09:47:21
Tagged date : UTC 2020-05-07 09:47:21
Color range : Limited
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709
Codec configuration box : avcC

Audio
ID : 2
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : 2 / 40 / mp4a-40-2
Duration : 8 h 6 min
Bit rate mode : Variable
Bit rate : 96.0 kb/s
Channel(s) : 1 channel
Channel layout : C
Sampling rate : 44.1 kHz
Frame rate : 43.066 FPS (1024 SPF)
Compression mode : Lossy
Stream size : 334 MiB (58%)
Title : ISO Media file produced by Google Inc. Created on: 05/07/2020.
Encoded date : UTC 2020-05-07 09:47:21
Tagged date : UTC 2020-05-07 09:47:21

8

There’s the problem.
It’s referring to this:

Try changing the file extension from “.mp3” to “.mp4”

9

If you haven’t done so already you’ll need to install the [u]FFmpeg import/export library[/u] in order to decode MP4.

Note that MP4 audio, M4A and AAC are all the same (or at least the same encoding).

10

I did that…

funny thing, in the folder the failename shows xxxx.mp4 and in the folder categories “type” it shows mp4


when i try to select it in audacity is shows as mp3 ???

11

THAT IS WEIRD!!!

MediaInfo also saw the filename as the_war_of_civilization.mp3

Maybe just re-type the whole file name. Or copy it and then re-name the copy.

Or once you get it properly opened in Audacity, you can export as M4A (AAC/MP4) and the new file will be good!




…What I said above about multiple generations of lossy compression does NOT apply to M4A. It’s still lossy compression but there is no accumulated damage from multiple encodes. So you might want to keep M4A if you don’t specifically-need MP3.

12

Have you set Windows File Explorer options to “show known file extensions”?

As both Audacity and MediaInfo OnLine show the file extension to be “.mp3”, I believe that the file extension IS “.mp3”.
Perhaps you are confusing two files with similar names?