Play AAC Files with TiVo Desktop 1.9 via fast LAME

Feb 23, '05 07:14:00AM

Contributed by: alanb1979

After digging around to learn more about TiVo Desktop 1.9 for Mac OS X, I learned about an interesting hidden feature: you can play back AAC files on your TiVo by using a transcoding feature. On the TiVo Community Forum thread about version 1.9, a user describes how you can use LAME to transcode unprotected AAC files. This doesn't get you iTunes Music Store DRMed AAC playback, but if you've ripped many other CDs in AAC (like I have), you'll be quite happy about this. The basic idea is this:

  1. Install the lame command line program in /usr/local/bin/lame. Or do fink install lame and then ln -s /sw/bin/lame /usr/local/bin/lame if you have Fink installed.
  2. Stop and restart TiVo Desktop via the Preference Pane
  3. Enjoy
On my dual-800 G4 powermac, the Fink version of lame used about 80% of one processor to do the real-time AAC to MP3 conversion. I was hoping to speed up the AAC-to-MP3 transcoding by compiling LAME on my own. This turned out to be very easy and gave quite an impressive performance improvement. Read the rest of the hint for the how-to...

Here are the steps on the command line for a G4 (from the blacktree forum). Note that the multi-line commands should be entered on one line.


$ cd ~ 
$ mkdir tmp 
$ cd tmp 
$ curl http://internap.dl.sourceforge.net/sourceforge/lame/lame-3.96.1.tar.gz\
 -o lame-3.96.1.tar.gz 
$ tar xvzf lame-3.96.1.tar.gz 
$ cd lame-3.96.1 
$ ./configure CFLAGS="-O3 -falign-loops-max-skip=15 -falign-jumps-max-skip=15 \
 -falign-loops=16 -falign-jumps=16 -falign-functions=16 -malign-natural -ffast-math \
 -fstrict-aliasing -funroll-loops -floop-transpose -mpowerpc-gpopt -fsched-interblock \
 --param max-gcse-passes=3 -fno-gcse-sm -mcpu=G4 -mtune=G4" 
$ make 
$ sudo make install 
$ cd ~ 
$ rm -rf tmp
After compiling, I compared the resulting binary program in /usr/local/bin/lame to the Fink-compiled lame, and found that the optimized version was 3.6x faster (7 versus 25 seconds) at compressing an MP3 with the default options. This optimization reduced my processor usage while transcoding with TiVo from 80% to 25%.

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