Does merging audio mess with overall quality?

Audacity Help Forum Windows
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Hi guys. I’m new to this forum and also to Audacity. I’m planning on using this program to edit my music files without losing quality. I need help understanding how this program works so I have a few questions:

  1. Can simply cutting off a part of a track and exporting it again as the same format (I’m talking about mp3 to mp3. If I have an flac, I will export it as mp3) slightly reduce it’s quality?
    2.What’s the difference between Joint stereo and Stereo in the saving options for mp3? Which one is preferable?
  2. I’ve noticed when I was pasting a part of a track (ending) to (the beginning) another track and clicked the merge option, the whole blue spectrum thingy (Idk what the term is) slightly changed in form yet when i listened to it, The quality was still the same. Knowing that occurrence, I thought that a change in spectrum thingy meant a change in quality also. Should i have just left the pasted track there and not merged it? Please bear with me, I slightly have OCD and unless everything’s perfect, I get uneasy.
  3. Does everything that come in and go out from Audacity have it’s quality reduced? (Converting, Cutting, Editing, etc.)
  4. Is there a way to compare the same parts of two tracks in Audacity? I want to see if what I edited lost some quality so I want to compare it with the original.
  5. Is File>Open the same as Import>Import Audio? (Notice in the “File>Open” method that Opening two files opens two windows of Audacity while Import puts the two tracks in the same window)

Thanks. i hope someone can answer my questions.

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I’m talking about mp3 to mp3.

Audacity doesn’t edit MP3 files. It makes a copy of the file in its own very high quality internal format and then makes a new MP3 when you’re done. The short story is you get double the MP3 compression distortion each pass.

You can get around this by Exporting (Audacity doesn’t save sound files) in a very high quality MP3 (256, 320) or one of the perfect formats like WAV. Most people want to make simple changes and walk away with the same size and quality MP3. Audacity won’t do that.

Never do production in MP3.

You should probably look into one of the pure MP3 editors. They have greatly reduced tricks, filters and effects, but the quality doesn’t go into the mud.

https://wiki.audacityteam.org/wiki/MP3_Editing_Tools

Koz

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  1. Can simply cutting off a part of a track and exporting it again as the same format (I’m talking about mp3 to mp3.

MP3 is lossy compression. Data is thrown-away during compression.

When you open a file in Audacity (or any “normal” audio editor) it gets decompressed. If you re-export to MP3 you are going through another generation of lossy compression and the “damage” does accumulate. You may not hear any quality loss, but it is a lossy format.

There are special purpose editors such as MP3directCut that can do limited editing without decompressing-recompressing.

If I have an flac, I will export it as mp3) slightly reduce it’s quality?

FLAC is lossless, and yes. Any time you export to MP3 or (AAC, etc.) there is “data” loss. AAC is more immune to damage from multiple generations of compression but it’s not totally immume.

If you import an MP3 and export as FLAC or WAV there is no additional damage… The loss happens during compression not during decompression.


2.What’s the difference between Joint stereo and Stereo in the saving options for mp3? Which one is preferable?

Joint Stereo is preferable. It’s “smarter” than regular stereo because sounds that are common between left & right ('center-channel" vocals, etc.) are only encoded once. This takes better advantage of the limited/compressed data so you can get better quality with the same file size/bitrate. And, Joint stereo is smart enough to encode separately if you have something like English on the left and French on the right where there’s no common sounds.


  1. I’ve noticed when I was pasting a part of a track (ending) to (the beginning) another track and clicked the merge option, the whole blue spectrum thingy (Idk what the term is)

It’s called a “waveform”. The normal waveform view is a time domain representation (amplitude vs. time) and it corresponds to the way digital audio is stored. A spectrum is a frequency domain representation.

slightly changed in form yet when i listened to it, The quality was still the same. Knowing that occurrence, I thought that a change in spectrum thingy meant a change in quality also. Should i have just left the pasted track there and not merged it?

If you’re “splicing” (adding the beginning of the 2nd track to the end of the 1st track) the quality won’t be affected. If you are mixing two or more sounds together, that can cause clipping (distortion).

  1. Does everything that come in and go out from Audacity have it’s quality reduced? (Converting, Cutting, Editing, etc.)

Generally, you only loose quality if you use lossy compression or if you reduce the “resolution” (converting 24-bit/96kHz to 16-bit/44.1kHz, etc.). However, that particular conversion is usually audibly transparent because CD quality (16-bit/'44.1kHz) is better than human hearing.

There is also [u]dither[/u]. Dither is intentionally added noise, which is supposed to improve the sound under certain conditions. But, it shouldn’t normally be audible and it can be turned-off.

For example, if you turn-off dither, open a lossless file, chop-off the last-half of a song, and re-export to the same format… The data for the 1st half of the song won’t be altered at all.


  1. Is there a way to compare the same parts of two tracks in Audacity? I want to see if what I edited lost some quality so I want to compare it with the original.

Watch for [u]clipping[/u], which can happen if you boost the level (or if you record “too loud”). Note that Audacity itself won’t clip so you may not hear it until after you export, or if you play at full-volume and clip your DAC. If you see the red clipping indicators, reduce the volume before exporting.

Otherwise, just listen. Of course effects (EQ, reverb, etc.) will affect the sound “quality”, but the intent is usually to improve the quality (often a matter of style/taste).

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By “mixing”, You mean merge the two tracks together, right? Or at least merge parts. I’m not doing that at all, I’m just basically copying the ending portion of a track to the beginning of the other track and give it a “fade in” effect to make it sound like the track from the album was never cut. Like, you know those Albums where the tracks weren’t separated properly and when you play the whole album according to their Track numbers they sound so smooth transitioning to the next track but when you turn on “Shuffle all songs” mode, You can hear the tracks abruptly ending. An Example Album would be from Green Day’s American Idiot, Track 3. “Holiday” and Track 4. Blvd of Broken Dreams.

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If you are mixing two or more sounds together, that can cause clipping

Actually, I didn’t write that. DVDdoug did.

You do have to be careful when you’re mixing multiple audios playing at once. Your particular application should be OK.

As an example, if you duplicated a track so two copies of the show play at the same time, the combined show volume would double. If the blue waveforms on one track were really close to 100%, the combined track would go over. Audacity has provision not to overload if you do that and you can safely reduce the volume in editing. But if you exported that work to a stand-alone sound file, it would sound like trash—forever.

Most sound file formats can’t go over 100% (0 dB).

Koz