Update: more links and ogg and webm details

I found that I needed to convert an m4a audio file (which is what QuickTime saves when I record audio) to a wav file, so I decided to use my favorite “can opener.” The versatile open source ffmpeg tool has always seemed to be able to convert anything to anything in audio-video formats.

I decided to pull the source from git:

$ git clone git://source.ffmpeg.org/ffmpeg.git
$ cd ffmpeg/


Stable versions are tagged (which I could see with “git tag -l”). I don’t need to live on the edge right now, so I switched to the tag “n0.9.1” which I assume is for the latest stable build “harmony” 0.9.1 and made a local branch based on that.

$ git co n0.9.1
$ git checkout -b n0.9.1


Instructions for building ffmpeg are in the “INSTALL” file. I discovered I needed yasm, which I could install with brew. Here’s what I did:

$ brew install yasm
$ ./configure
$ make
CC libavdevice/alldevices.o
CC libavdevice/avdevice.o
CC libavdevice/lavfi.o
AR libavdevice/libavdevice.a
CC libavfilter/af_aconvert.o
libavfilter/af_aconvert.c:53: warning: function declaration isn’t a prototype
libavfilter/af_aconvert.c:105: warning: function declaration isn’t a prototype
CC libavfilter/af_aformat.o
CC libavfilter/af_anull.o
CC libavfilter/af_aresample.o
:
:
ffserver.c: In function ‘parse_ffconfig’:
ffserver.c:4236: warning: ‘avcodec_get_context_defaults2’ is deprecated (declared at ./libavcodec/avcodec.h:3948)
ffserver.c:4237: warning: ‘avcodec_get_context_defaults2’ is deprecated (declared at ./libavcodec/avcodec.h:3948)
LD ffserver_g
CP ffserver
STRIP ffserver

I saw a lot of warnings, but they didn’t seem to negatively affect what I was trying to do. I found a nice blog post from catswhocode to remind me of the usage, and was able to use this simple command:


$ ./ffmpeg -i frog.m4a frog.wav
ffmpeg version 0.9.1, Copyright (c) 2000-2012 the FFmpeg developers
built on Jan 7 2012 21:19:08 with llvm_gcc 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2335.15.00)
configuration:
libavutil 51. 32. 0 / 51. 32. 0
libavcodec 53. 42. 4 / 53. 42. 4
libavformat 53. 24. 2 / 53. 24. 2
libavdevice 53. 4. 0 / 53. 4. 0
libavfilter 2. 53. 0 / 2. 53. 0
libswscale 2. 1. 0 / 2. 1. 0
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'frog.m4a':
Metadata:
major_brand : M4A
minor_version : 0
compatible_brands: M4V M4A mp42isom
creation_time : 2012-01-08 05:09:05
Duration: 00:00:07.22, start: 0.000000, bitrate: 206 kb/s
Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, s16, 201 kb/s
Metadata:
creation_time : 2012-01-08 05:09:05
handler_name :
Output #0, wav, to 'frog.wav':
Metadata:
major_brand : M4A
minor_version : 0
compatible_brands: M4V M4A mp42isom
creation_time : 2012-01-08 05:09:05
encoder : Lavf53.24.2
Stream #0:0(und): Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, stereo, s16, 1411 kb/s
Metadata:
creation_time : 2012-01-08 05:09:05
handler_name :
Stream mapping:
Stream #0:0 -> #0:0 (aac -> pcm_s16le)
Press [q] to stop, [?] for help
size= 1244kB time=00:00:07.22 bitrate=1411.3kbits/s
video:0kB audio:1244kB global headers:0kB muxing overhead 0.003611%

$ ls
frog.m4a frog.wav


Success!!