Converting files to OGG with FFMPEG produces an extremely large file

Question

When trying to convert either an mp3 or flac file to ogg, the output ogg file is actually a flac file with a large file size.

For instance: running for file in *.mp3; do ffmpeg -i "${file}" "${file/%mp3/ogg}"; done and then checking the file with mediainfo output.ogg gives:

General
Complete name                            : 06 - Magma.ogg
Format                                   : Ogg
Format/Info                              : Free Lossless Audio Codec
File size                                : 47.0 MiB
Duration                                 : 6mn 42s
Overall bit rate mode                    : Variable
Overall bit rate                         : 980 Kbps

Audio
ID                                       : 1238237382 (0x49CE00C6)
Format                                   : FLAC
Format/Info                              : Free Lossless Audio Codec
Duration                                 : 6mn 42s
Bit rate mode                            : Variable
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Sampling rate                            : 44.1 KHz
Bit depth                                : 16 bits
Writing library                          : Lavf57.37.100

The input mp3 in my case was 6 megabytes, but the ogg file is for some reason 47 megabytes. Why is this happening, and is there a why to convert files to ogg without this happening?

Answer 1

As you can see in the output, you encoded your audio into Format : FLAC. This is a format with lossless compression. ogg is just a container, and can hold different formats. To keep a similar size and quality as your mp3 you can choose the more usual vorbis format explicitly:

ffmpeg -i in.mp3 -c libvorbis out.ogg

The fact that it did not do this by default may mean you need to install a libvorbis package, depending on your system.