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What mp3 quality do you want?

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Greg LindenJul 23, 2009
 

 
That's brilliant! Thanks *so* much for setting me straight.

I can use the free version of Switch for Mac
(http://www.nch.com.au/switch/index.html) to go aac-to-mp3 (160k
seems to preserve quality). Or 4x faster is Switch for aac-to-aiff
then iTunes for aiff-to-mp3 (still using 160k).

Thanks for making my life a lot easier!

PS: In get_iplayer, adding the option "--amode=flashaac" will
retrieve the aac version.

At 6:38 PM +0100 7/23/09, Clitheroe Kid wrote:

>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
>> >> >
>> >> >
>> >> >
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