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What mp3 quality do you want?

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Clitheroe KidJul 23, 2009
 

 
The BBC were originally using 128kbps mp3 (throughout 2008) on the iPlayer.

The page you mention deals only with some tests they conducted last
February, at a point when they were considering using a reduced bitrate of
96kbps, bolstered by AAC+ to offset the bitrate reduction.

Since then they've migrated to 128kbps AAC. The software I use (Winamp 5,
Media Player Classic, and RTMPdump) reports that they're now using AAC-LC.

----- Original Message -----
From: "Greg Linden" <gmlinden@...>
To: <just-a-minute@...>
Sent: Thursday, July 23, 2009 12:00 AM
Subject: [just-a-minute] Re: What mp3 quality do you want?


> Look at this table from February:
>
http://www.digitalradiotech.co.uk/2009/02/bbc_test_aac+_streams_overtake_dab_quality.php
> = http://tinyurl.com/dmakzp
> The on-demand stream for Radio 4 is listed as 96k AAC+. It also
> mentions that the Flash window will report simple AAC (not AAC+)
> regardless of which type it is.
> Greg
>
> At 10:07 PM +0100 7/22/09, Clitheroe Kid wrote:
> >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
> >>
> >>
> >>
> >>
> >
> >
> >
> >------------------------------------
> >
> >Yahoo! Groups Links
> >
> >
> >
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>
>

 
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