几乎没有什么事情比听你最喜欢的音乐突然让一首或多首歌曲以较低的音量播放更令人沮丧的了。有没有一种简单的方法可以在不牺牲质量的情况下解决音量问题？今天的超级用户问答帖子帮助一位沮丧的读者解决了音量问题。

今天的问答环节是由SuperUser提供的，SuperUser是Stack Exchange的一个分支，是一个由社区驱动的问答网站分组。

问题

超级用户阅读器user602675想知道是否有可能无损地增加mp3文件的音量：

I want to increase the volume of some mp3 files that I have. Are there any methods of doing this in a lossless way without recompressing the mp3 files and thus decreasing their quality?

你能无损地增加mp3文件的音量吗？

答案

超级用户贡献者Mokubai为我们提供了答案：

Yes, you can do this. The technique is used by a number of programs and the levels are calculated by an algorithm called ReplayGain. MP3 volume level data can be adjusted losslessly, just as a JPEG picture can be losslessly rotated. There are two methods:

1. Calculate the volume level of the file and add a new tag, letting compatible programs adjust the volume on the fly.
2. Calculate the volume level and adjust a multiplier level in the mp3’s data.

From HydrogenAudio (Implementati***):

The second method does alter your file, but because the underlying data is not modified it loses no quality, hence the adjustment can be done losslessly. It is not generally recommended for your main collection as it is modifying the files from their original state, but it can be very useful for portable media players.

A program called MP3Gain can perform the second option and reversibly adjust the volume of mp3s. It does absolutely no re-encoding and simply adjusts magnitude values in the mp3 file itself to change the volume.

From HydrogenAudio (ReplayGain):

Due to the way mp3 files are encoded, the adjustment is limited to 1.5dB steps, which is usually enough to get close. Foobar2000 also includes this functionality and can apply the changes to the files.

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