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What mp3 quality do you want?

Messages in this topic: 11 View All
Clitheroe KidJul 22, 2009
 

 
You've suggested that the BBC's audio iPlayer files are using HE AAC (a.k.a.
AAC+). However, according to the BBC website, the BBC uses LC-AAC, not
AAC-HE.

----- Original Message -----
From: "Greg Linden" <gmlinden@...>
To: <just-a-minute@...>
Sent: Wednesday, July 22, 2009 6:48 PM
Subject: [just-a-minute] Re: What mp3 quality do you want?


> The format that get_iplayer extracts from the flashaac mode is
> actually "aacPlus", which retains excellent quality in a very small
> file. http://dictionary.zdnet.com/definition/aacplus.html
>
> Unfortunately for Mac users, QuickTime still doesn't support it. On
> a Mac, the only native apps I've found that play aacPlus files are
> VLC and RealPlayer. I run WinAmp in Parallels to convert to wav or
> high-bit m4a then iTunes to transcode to mp3.
>
> Greg
>
> At 6:23 PM +0100 7/22/09, Clitheroe Kid wrote:
> >The extension commonly used by iTunes files is .m4a (which stands for mp4
> >audio). This is simply an mp4 file which contains only an audio stream.
MP4
> >is a video format, so usually has both a video stream and an audio
stream.
> >
> >The program ffmpeg has an option to save a raw .AAC file as an MP4 file
> >(with the extension .mp4 or .m4a), without re-encoding the file.
> >
> >An audio-only MPEG-4 file can be named either .mp4 or .m4a since those
types
> >of file are both encoded in exactly the same way, but the latter is only
> >encoding audio (instead of audio and video).
> >
> >AAC is a type of MPEG-4 file. But a raw AAC file won't play in iTunes
merely
> >by changing the file's extension from .aac to .mp4, because you have to
do
> >more to the file than that! It has to be "muxed" in order to become an
mp4
> >file. That doesn't involve re-encoding it! It has to do with creating a
> >frame header for each frame, one that iTunes can read.
> >
> >MP4 is a video format, so it uses frames (normally 25 frames per second,
the
> >standard video format). Each frame has a header (a few bytes, describing
the
> >audio format of the data stream). FFMPEG can add those headers to the raw
> >AAC data, to create a fully valid MP4 file.
> >
> >Almost *any* player can play an mp4 file (though iTunes might need the
> >file's extension to be renamed to .m4a).
> >
> >Stephen
> >
> >
> >----- Original Message -----
> >From: "eriatarkae@..." <eriatarka1@...>
> >To: <just-a-minute@...>
> >Sent: Wednesday, July 22, 2009 1:56 PM
> >Subject: [just-a-minute] Re: What mp3 quality do you want?
> >
> >
> >> There are a few caveats to this. Firstly, the raw .aac files don't
appear
> >to play in iTunes (Quicktime only), and changing the extension doesn't
help
> >either. This is a huge problem for me, as iTunes is my central storage
for
> >all things JAM. Secondly, I'm fairly sure that .aac is not a suitable
format
> >for most people's usual use patterns - most mp3 players can't play it,
and
> >car stereos don't usually play it either.
> >>
> >> As far as utilities go, they are not freeware. There's Quicktime Pro
or,
> >for Macs, Fission. Quicktime Pro is useful, because if you trim to the
> >selection (which is not immediately obvious, but there's a selection
ruler
> >across the bottom) and save as an .mp4, then that will play in iTunes.
> >Fission - I have no idea, I'm on XP.
> >>
> >> Robert
> >
> >
> >
> >------------------------------------
> >
> >Yahoo! Groups Links
> >
> >
> >
>
>
> ------------------------------------
>
> Yahoo! Groups Links
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