This guide is old and outdated.
If you want to do exact cuts on mp3s, please read t/84226
If you want to just trim the start or end of the song, please use t/34303
===================
Recently, the ranking requirements changed to require all maps to have a bite rate average between 128 and 192, so that means that all 320 kbps bit rate songs must be re-encoded. Sadly, not everyone knows how to re-encode files, but with this simple guide, you can become an expert at re-encoding mp3s.
Needed Programs:
Audacity 1.3 beta (for this example, I'll be using version 1.3.12, but any working version of the beta is fine (thanks to Xgor for pointing this out))
If you want to use an Audacity 1.2, the way to re-encode the file is slightly different.
1. Open Audacity
2. Import your song into Audacity (Audacity has a drag and drop feature, so you can grab an mp3 icon, hover it on top of audacity, and release to import the mp3 into Audacity)
If you did the first 2 steps right, your Audacity should look something like this:
3. Click on File->Export...
4. Now a window asking where to save your new mp3 pops up. Do not save anything yet. Instead press the button on the bottom right labeled "Options..."
5. As you can see in the menu, there are many ways to encode files. To meet ranking standards, you can follow the picture above and use a constant bit rate of 192kbps. Besides that, you can also try to do an average bit rate of 192 kbps, or variable bit-rate at V2 to meet the ranking standards.
6. Once you are done with setting how you want the file encoded, find where you want to save the file and press save.
7. After you press save, a window pops up saying if you want to edit the metadata of the mp3. Unless you want to change the metadata, just click "Ok" to continue
8. Wait for your file to encode.
Yay, now you have successfully re-encoded your mp3. Give yourself a pat on the back. You deserve it. Truthfully, re-encoding an mp3 is this easy. Now, share your new found skill with others and please help with http://osu.ppy.sh/forum/viewtopic.php?f=60&t=36657 if you have time.
=====================================================================
Here are some more advanced steps you can do to keep the offset the same in your new re-encoded mp3 (Please be able to find a single offset before attempting to follow these next few steps)
If you want to do exact cuts on mp3s, please read t/84226
If you want to just trim the start or end of the song, please use t/34303
===================
Recently, the ranking requirements changed to require all maps to have a bite rate average between 128 and 192, so that means that all 320 kbps bit rate songs must be re-encoded. Sadly, not everyone knows how to re-encode files, but with this simple guide, you can become an expert at re-encoding mp3s.
Needed Programs:
Audacity 1.3 beta (for this example, I'll be using version 1.3.12, but any working version of the beta is fine (thanks to Xgor for pointing this out))
If you want to use an Audacity 1.2, the way to re-encode the file is slightly different.
1. Open Audacity
2. Import your song into Audacity (Audacity has a drag and drop feature, so you can grab an mp3 icon, hover it on top of audacity, and release to import the mp3 into Audacity)
If you did the first 2 steps right, your Audacity should look something like this:
3. Click on File->Export...
4. Now a window asking where to save your new mp3 pops up. Do not save anything yet. Instead press the button on the bottom right labeled "Options..."
5. As you can see in the menu, there are many ways to encode files. To meet ranking standards, you can follow the picture above and use a constant bit rate of 192kbps. Besides that, you can also try to do an average bit rate of 192 kbps, or variable bit-rate at V2 to meet the ranking standards.
6. Once you are done with setting how you want the file encoded, find where you want to save the file and press save.
7. After you press save, a window pops up saying if you want to edit the metadata of the mp3. Unless you want to change the metadata, just click "Ok" to continue
8. Wait for your file to encode.
Yay, now you have successfully re-encoded your mp3. Give yourself a pat on the back. You deserve it. Truthfully, re-encoding an mp3 is this easy. Now, share your new found skill with others and please help with http://osu.ppy.sh/forum/viewtopic.php?f=60&t=36657 if you have time.
=====================================================================
Here are some more advanced steps you can do to keep the offset the same in your new re-encoded mp3 (Please be able to find a single offset before attempting to follow these next few steps)
Advance Technique
Please make sure Audacity stays open with your original mp3 from your previous re-encoding
9. Find the offset of you new re-encoded mp3
10. Compare the offset of your new mp3 with your old one to find how many ms of extra length was added to your mp3 (it tends to range from 40-60ms)
11. Go back to Audacity, and zoom in on the beginning of the sound pressure chart for your mp3. Make sure that the blank space is larger than the difference in offset you found in step 10. (If the blank space is smaller, then you can't keep the offset the same for the mp3 unless you are willing to sacrifice some of the song)
12. Select the time in the mp3 between 0.000s and your change in offset (The easiest way to do this is to go to the bottom of audacity, right click the little boxes saying the selection time, change it so that they show ms, and type in the correct times in both boxes)
13. Click the "Cut" button.
14. Repeat steps 3-8 to export your re-encoded mp3 with the same offset (Make sure to re-encode the file the same way you did steps 3-8 originally)
(Note there might be 1-2 ms change in the offset for various reasons, so do adjustments as necessary
9. Find the offset of you new re-encoded mp3
10. Compare the offset of your new mp3 with your old one to find how many ms of extra length was added to your mp3 (it tends to range from 40-60ms)
11. Go back to Audacity, and zoom in on the beginning of the sound pressure chart for your mp3. Make sure that the blank space is larger than the difference in offset you found in step 10. (If the blank space is smaller, then you can't keep the offset the same for the mp3 unless you are willing to sacrifice some of the song)
12. Select the time in the mp3 between 0.000s and your change in offset (The easiest way to do this is to go to the bottom of audacity, right click the little boxes saying the selection time, change it so that they show ms, and type in the correct times in both boxes)
13. Click the "Cut" button.
14. Repeat steps 3-8 to export your re-encoded mp3 with the same offset (Make sure to re-encode the file the same way you did steps 3-8 originally)
(Note there might be 1-2 ms change in the offset for various reasons, so do adjustments as necessary
