Just A Minute

 
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What mp3 quality do you want?

Messages in this topic: 9 View All
Greg LindenJul 22, 2009
 

 
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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