I'm going to be encoding some videos in a week or so and I'm having trouble deciding which audio codec to use. I'll give some details so I can get the best choice for the job.

Audio codecs to choose from: AAC (through Nero Encoder), MP3 (through LAME), and Vorbis

Encoding Specs: 128kb/s, 44100 sample rate, two channel stereo

AAC and Vorbis will deliver similar quality. AAC might have an edge in compatibility (for hardware players), but that won't be an issue if this video is strictly for computers.

Don't bother with MP3, it's obsolete.

Make sure you use VBR or ABR.

What kind of video sources do you have? What is the source codec? PCM? AC3?

In case it's AC3... what about not transcoding at all?

How about H.264 (x264) + AAC (Nero) ?
With "-q0.35" you usually end up with good quality at around 96 kbps
(imho totally sufficient as video sound track)

You can put it into a Matroska- or MP4-container.

why would you have trouble in deciding?

I love this combination, and the MP4 container makes things so neat.

I had a play with my DVD of Pan's Labyrinth, and created an MP4 with subtitles, ~96kbps audio, and ~48kbps director's commentary all in one nice neat MP4 file. Much tidier than an AVI with SRT.

I'd use AAC.

Where did those specs come from? What is this video going to be played-back on?

At 128kbps, none of these formats will be "near CD quality", so it may not matter that much. If your question is which will sound best, I'll leave that for others. I just try to avoid lossy compression whenever possible, and I've never personally done any A/B tests.


MP3 is still the most popular, most universal, "play anywhere" format. You can play an MP3 on any PC, any MAC, your iPod, your Zune, or any other digital player. (Once you multiplex the MP3 into an audio/video file, it is not as universal.)

I assume you mean technically outdated? "Obsolete" generally means "no longer in use" I'd say 8-Track tapes are obsolete. I'd say VHS is becomming obsolete, but most of us still have a VCR. HD-DVD and BluRay are more advanced than DVD, but DVD is not becomming obsolete yet.

Discussion related to MP4 muxing moved to here.

Edit: in relation to the original topic.

It really depends on what application your talking about here. If you are looking to just view the resulting encode on a PC, then I thoroughly recommend AAC muxed as part of an MP4 file. This file should be fairly portable anyway (depending on the settings the video and audio are encoded with). Whilst DVDDoug is right in saying that MP3 is still the most popular codec, it is not the most standards compliant; VBR MP3 in AVI is a pretty big hack. MP3 can be used in MP4, but you might as well use AAC. For video, in my opinion, 128k/bits LC AAC for Stereo will be fine, particularly if the source is lossy (like an audio track from a DVD) or the file is not intended to be of archival quality.