1 ==========================================================================
2 fdkaac - command line frontend encoder for libfdk-aac
3 ==========================================================================
8 On Posix environment, you will also need GNU gettext (for iconv.m4) and
11 How to build on Posix environment
12 ---------------------------------
13 First, you need to build libfdk-aac and install on your system.
14 Once you have done it, the following will do the task.
15 (MinGW build can be done the same way, and doesn't require gettext/iconv)
18 $ ./configure && make && make install
22 First you have to extract libfdk-aac source here, so that directory tree will
23 look like the following:
24 +- fdk-aac ---+-documentation
33 MSVC solution for Visual Studio 2010 is under MSVC directory.
35 Available input format
36 ----------------------
37 WAV (or RF64), upto 32bit int / 64bit float format is supported.
38 However, since FDK AAC encoder is implemented based on fixed point integer,
39 encoder itself treats 16bit input only.
40 Therefore, when feeding non-integer input, be careful so that input doesn't
41 exceed 0dBFS to avoid hard clips.
42 You might also want to apply dither/noise shape beforehand when your input
43 has higher resolution.
45 Note that fdkaac doesn't automatically resample for you
46 when input samplerate is not supported by AAC spec.
50 Generic tagging options like --tag, --tag-from-file, --long-tag allows you
51 to set arbitrary tags.
52 Available tags and their fcc (four char code) for --tag and --tag-from-file
53 can be found at http://code.google.com/p/mp4v2/wiki/iTunesMetadata
55 For tags such as Artist where first char of fcc is copyright sign,
56 you can skip first char and just say like --tag="ART:Foo Bar" or
57 --tag-from-file=lyr:/path/to/your/lyrics.txt
59 Currently, --tag-from-file just stores file contents into m4a without any
60 character encoding / line terminater conversion.
61 Therefore, only use UTF-8 (without BOM) when setting text tags by this option.
63 On the other hand, --tag / --long-tag (and other command line arguments) are
64 converted from locale character encoding to UTF-8 on Posix environment.
65 On Windows, command line arguments are always treated as Unicode.
69 With --tag-from-json, fdkaac can read JSON file and set tags from it.
70 By default, tags are assumed to be in the root object(dictionary) like this:
73 "title": "No Expectations",
74 "artist": "The Rolling Stones",
75 "album": "Beggars Banquet",
79 In this case, you can simply specify the filename like:
80 --tag-from-json=/path/to/json
82 If the object containing tags is placed somewhere else, you can optionally
83 specify the path of the object with dotted notation.
87 "filename" : "Middle Curse.flac",
89 "format_name" : "flac",
90 "format_long_name" : "raw FLAC",
92 "duration" : "216.146667",
93 "size" : "11851007.000000",
94 "bit_rate" : "438628.000000",
96 "ALBUM" : "Scary World Theory",
97 "ARTIST" : "Lali Puna",
99 "DISCID" : "9208CC0A",
100 "TITLE" : "Middle Curse",
107 In this example, tags are placed under the object "format.tags".
108 ("format" is a child of the root, and "tags" is a child of the "format").
109 In this case, you can say:
110 --tag-from-json=/path/to/json?format.tags
112 For your information, ffprobe of ffmpeg project (or avprobe of libav) can
113 output media information/metadata in json format like this.
115 Note that not all tags can be read/written this way.