Audio Examples: MP3 vs. AAC/M4A vs. Opus

In this previous thread we discussed the difference between the LAME and Fraunhofer CBR MP3 encoder at low bitrates:
https://plus.google.com/u/0/117038174657625698320/posts/ca1TxQUhaDj
So far there was no audio example where one could hear a relevant difference between both.

At the end of the discussion, some people were interested in the AAC codec, to get smaller podcast files with better quality.
Here I post some examples - encoded in AAC, in MP3 and in Opus - so that it is possible to compare the audio quality at various (low) bitrates.
I will add some personal comments to those files later, so that everyone can listen to them without reading my comments first.

You can listen to all files with a recent firefox, as it ships all necessary decoders.
(AFAIK Safari is still (the only?) browser which does not ship an opus decoder)


Example1: Mono file, speech only

This mono file contains female and male speakers.

Here is the uncompressed WAV file:
https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono.wav

64kbps (28MB/h):
- mp3: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-64k.mp3
- aac: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-64k.m4a
- opus: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-64k.opus

48kbps (21MB/h):
- mp3: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-48k.mp3
- aac: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-48k.m4a
- opus: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-48k.opus

32kbps (14MB/h):
- mp3: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-32k.mp3
- aac: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-32k.m4a
- opus: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-32k.opus

24kbps (11MB/h):
- mp3: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-24k.mp3
- aac: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-24k.m4a
- opus: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-24k.opus

16kbps (7MB/h):
- mp3: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-16k.mp3
- aac: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-16k.m4a
- opus: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-16k.opus

12kbps (5MB/h):
- mp3: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-12k.mp3
- aac: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-12k.m4a
- opus: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-12k.opus

6kbps (3MB/h):
- opus: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinMono-12k.opus


Example2: Stereo file, speech with music intro

This stereo file starts with a music intro, then contains female and male speakers.

Uncompressed WAV file:
https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo.wav

96kbps (42MB/h):
- mp3: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-96k.mp3
- aac: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-96k.m4a
- opus: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-96k.opus

64kbps (28MB/h):
- mp3: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-64k.mp3
- aac: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-64k.m4a
- opus: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-64k.opus

48kbps (21MB/h):
- mp3: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-48k.mp3
- aac: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-48k.m4a
- opus: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-48k.opus

32kbps (14MB/h):
- mp3: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-32k.mp3
- aac: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-32k.m4a
- opus: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-32k.opus

24kbps (11MB/h):
- mp3: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-24k.mp3
- aac: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-24k.m4a
- opus: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-24k.opus

16kbps (7MB/h):
- mp3: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-16k.mp3
- aac: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-16k.m4a
- opus: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-16k.opus

12kbps (5MB/h):
- mp3: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-12k.mp3
- aac: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-12k.m4a
- opus: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-12k.opus

6kbps (3MB/h):
- opus: https://auphonic.com/media/audio-examples/encoders/BitsOfBerlinStereo-12k.opus


It should be possible to reduce the file size and improve the quality when using AAC encoded files for a podcast.
Shared publiclyView activity