M4A / AAC changes - Which ffmpeg version is required ?

[Martin Williams]

Many thanks to all for the input.

I can confirm that the 'trick' is working with ffmpeg v0.6.1,
specifically SVN-r25838.

I notice that support for the faad aac decoding library has been
removed since v0.6. Perhaps ffmpeg's own aac decoder does things a
little differently.


I failed to mention that I am running OSX Leopard on an iMac PPC G5,
which is not supported by Homebrew (Intel Macs only). In fact support
for this model is falling away alarmingly. That's a pity, because it
continues to work well for me.

One troublesome aspect of the build was that an altivec optimization
within libavcodec fails to compile. These optimizations appear to have
been substantially rewritten since ffmpeg v0.6. It looks as if the
problem remains with the later versions of ffmpeg, but I haven't double
checked.

Building with XCode 3.14, gcc 4.0.1, and the current (26 Sept 2010) yuvi
gas-preprocessor script properly installed, the error shows up as:

AS	libavcodec/ppc/fft_altivec_s.o
libavcodec/ppc/fft_altivec_s.S:747:Parameter syntax error (parameter 2)
libavcodec/ppc/fft_altivec_s.S:747:Invalid mnemonic 'got(r2)'
...
libavcodec/ppc/fft_altivec_s.S:1329:Parameter syntax error (parameter 2)
libavcodec/ppc/fft_altivec_s.S:1329:Invalid mnemonic 'got(r2)'
make: *** [libavcodec/ppc/fft_altivec_s.o] Error 1

In case anyone comes up against the same problem an easy solution is to
disable altivec optimizations by configuring with the option
'--disable-altivec'.


I obtained the source tarball from the Debian multimedia project. This
particular version is their current stable package for Debian Squeeze,
so I'll be be able to install that on my little arm box in due course,  
in
the expectation/hope that ffmpeg will work identically on both machines.

http://debian-multimedia.org/pool/main/f/ffmpeg-dmo/ffmpeg-dmo.php
ffmpeg-dmo_0.6.1+svn20101128.orig.tar.gz


Apologies if this post inadvertently starts a new thread.

mw