[mythtv-users] MP3Pro support

[Michael T. Dean]

Kevin Kuphal wrote:

>I believe they are (at least from the documentation) but since the MP3pro is
>geared around improving quality at low bitrates, it wouldn't surprise me
>that a standard MP3 player playing a low bitrate MP3pro file would sound
>significantly worse.
>  
>
Exactly, MP3Pro--as mentioned earlier in the thread--is a proprietary, 
patented format by Thomson Multimedia and the Fraunhofer Institute.  It 
uses a proprietary, patented audio coding enchancement tool called 
Spectral Band Replication (SBR) owned by Coding Technologies.

MP3Pro will work with software and devices that only understand MP3.  
However, MP3Pro uses two separate streams of data to improve audio 
quality and "standard MP3" players can only detect one.  Since MP3Pro 
typically uses a lower-bitrate to approximate the quality of a 
higher-bitrate MP3 stream, and since MP3 players only use one of the two 
streams, MP3 players will sound as if they are playing an even lower 
bitrate MP3 stream.  For example, a 64kbps MP3Pro uses approximately 
60Kbps to encode _only_ the low-frequency part of the audio.  This part 
is played by an MP3 player.  An MP3Pro player uses SBR to "recreate" the 
high-frequency portion of the audio based on the other 4Kbps in the 
stream.  Therefore, MP3Pro files played on a standard MP3 player sound 
significantly worse than when played on an MP3Pro player.

So, why not use a free audio CODEC, like Ogg Vorbis or FLAC?  Vorbis is 
similar to AAC (Advanced Audio Coding) and WMA (Windows Media Audio) in 
terms of quality; therefore, it is better quality than MP3 and even 
MP3Pro.  Note, though, that all of those are "lossy" formats (output 
quality is lower than input quality).  If you really want quality, go 
with FLAC (Free Lossless Audio CODEC).  FLAC should give you audio 
quality equivalent to the input (i.e. rip a CD to FLAC, get CD quality 
output).  In terms of compression ratio, it depends on the input.  
Compressing white noise with FLAC will give an output approximately the 
same size as the input, but compressing silence will give an output of 
almost 0.

If you want to be able to play the audio from Windows (shudders) as well 
as Myth, there are even plugins for most popular media players that 
handle these formats.

HTH.

Mike