I encoded a .wav to an .mp3 with Lame, but somehow the encoded file is about 1 minute longer than the original (60 minutes vs 61 minutes, roughly).
3 minutes into the audio, the mp3 is already several seconds ahead of the wav. This is a problem because I want to mux the mp3 into a video and things need to be in sync.

The original is 48 kHz, 16bit mono which Lame downsamples to 44100 Hz.
The settings I used were -V6 --vbr-new -q0, I am using Lame version 3.97.
I also tried -abr 64 instead of -V6 which didn't help.

The wav is only spoken words with a lot of silence in between, plus the first 26 seconds are silent. I wonder if the silent parts could be causing this?

Has anyone experienced this? Am I doing something wrong?

Hi, welcome to Hydrogenaudio!

Hmmm.... LAME should handle 48 kHz input just fine, AFAIK.

Could you tell me which program you used to check the timing, please? Maybe it would be different with a program that fully supports VBR (VBRI headers, LAME tag, etc.) such as foobar2000.

I've just checked with LAME 3.98 beta 3 and LAME 3.97. It does resample 48 kHz 16bit mono to 44.1 kHz mono, with your command line settings. Weird...

Adding --resample 48000 seems to prevent the resampling.

Thank you. It turned out to be Windows Media Player's fault. I followed your advice and installed Foobar2000 which plays the mp3s just fine.

What's funny though is that if I mux the mp3 into an .avi and play the .avi in Windows Media Player, the audio is the right speed.

Anyhow, thanks!