ffmpeg 支持aac格式转换

网上搜了一下命令为：

ffmpeg -i 20120814164324_205.wav -acodec libfaac output.aac

出现了如下提示，没有找到编码器

Unknown encoder 'libfaac'

那就先去下载

 http://downloads.sourceforge.net/faac/faac-1.28.tar.gz

重新安装ffmpeg

 ./configure --enable-libopencore-amrnb --enable-version3  --enable-libfaac --enable-nonfree

make 

make install

declare -x LD_LIBRARY_PATH="/usr/local/lib:/ffmpeg/yasm-1.1.0:/ffmpeg/opencore-amr-0.1.2:/ffmpeg/faac-1.28"

再次执行命令

ffmpeg -i 20120814164324_205.wav -acodec libfaac output.aac

又出错了，缺少点参数

 libfaac doesn't support this output format

Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height

加点参数继续测试

ffmpeg -i 20120814164324_205.wav -acodec  libfaac -ab 64k -ar 44100  output.aac

输出：

[root@Server201 ffmpeg]# ffmpeg -i 20120814164324_205.wav -acodec  libfaac -ab 64k -ar 44100  output.aac
ffmpeg version 1.0 Copyright (c) 2000-2012 the FFmpeg developers
  built on Nov 29 2012 14:42:59 with gcc 4.1.2 (GCC) 20080704 (Red Hat 4.1.2-46)
  configuration: --enable-libopencore-amrnb --enable-version3 --enable-libfaac --enable-nonfree
  libavutil      51. 73.101 / 51. 73.101
  libavcodec     54. 59.100 / 54. 59.100
  libavformat    54. 29.104 / 54. 29.104
  libavdevice    54.  2.101 / 54.  2.101
  libavfilter     3. 17.100 /  3. 17.100
  libswscale      2.  1.101 /  2.  1.101
  libswresample   0. 15.100 /  0. 15.100
[wav @ 0x18214240] max_analyze_duration 5000000 reached at 5120000
Guessed Channel Layout for  Input Stream #0.0 : mono
Input #0, wav, from '20120814164324_205.wav':
  Duration: 00:00:10.99, bitrate: 64 kb/s
    Stream #0:0: Audio: pcm_alaw ([6][0][0][0] / 0x0006), 8000 Hz, mono, s16, 64 kb/s
Output #0, adts, to 'output.aac':
  Metadata:
    encoder         : Lavf54.29.104
    Stream #0:0: Audio: aac, 44100 Hz, mono, s16, 64 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_alaw -> libfaac)
Press [q] to stop, [?] for help
size=      86kB time=00:00:11.00 bitrate=  64.0kbits/s    
video:0kB audio:86kB subtitle:0 global headers:0kB muxing overhead 0.000000%

成功了！