Comment 77 for bug 602934

(In reply to comment #64)
> AC3 import OK. AC3 export gives a zero byte file but the same happens with
> standalone ffmpeg at the command line "LIBAVUTIL_50 not defined in file
> libavutil.so.50 with link time reference". I gather I may have to find
> libavcore, from Googling the error?
>
Not sure why you got that error, but I too get an empty AC3 export. I checked
the Audacity log and found:

01:07:58: Debug: Log: [ac3 @ 0x1d26d400] Specified sample_fmt is not supported.
01:07:58: Error: FFmpeg : ERROR - Can't open audio codec 0x15003.

Apparently, on Jan 4th, 2011, the default AC3 encoder now ONLY accepts FLOAT
samples. It's the only encoder (near as I can tell) that is like this. The
only other encoder that accepts FLOAT is the PCM fella, but he accepts all of
the formats so he's not a problem.

The older encoder has been renamed to ac3_fixed. Not sure of the best
approach:

1) Make the Audacity exporter capable of supplying one of the sample formats
supported by the encoder
2) Just force usage of the ac3_fixed encoder since he's the only one like
this.

> M4A import OK. Can't test M4A export as disabling the native aac encoder didn't
> give me libfaac so I will try again later with --enable-libfaac.
Here's the parameters I'm using for the Windows and Mac builds:

    sh ./configure --arch=i386 \
                   --cc=gcc-4.0 \
                   --disable-ffplay \
                   --disable-ffprobe \
                   --disable-ffserver \
                   --disable-avdevice \
                   --disable-debug \
                   --disable-encoder=aac \
                   --disable-decoder=amrnb \
                   --disable-decoder=amrwb \
                   --disable-static \
                   --disable-doc \
                   --enable-gpl \
                   --enable-nonfree \
                   --enable-version3 \
                   --enable-libopencore-amrnb \
                   --enable-libopencore-amrwb \
                   --enable-pthreads \
                   --enable-libfaac \
                   --enable-libspeex \
                   --enable-libgsm \
                   --enable-libmp3lame \
                   --enable-memalign-hack \
                   --enable-shared