]> iEval git - fdkaac.git/blame - README
refactor pcm io routines
[fdkaac.git] / README
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48e2f01c 1==========================================================================
2fdkaac - command line frontend encoder for libfdk-aac
3==========================================================================
4
5Prerequisites
6-------------
e9014663 7You need libfdk-aac.
8On Posix environment, you will also need GNU gettext (for iconv.m4) and
9GNU autoconf/automake.
10
11How to build on Posix environment
12---------------------------------
13First, you need to build libfdk-aac and install on your system.
14Once 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)
48e2f01c 16
48e2f01c 17$ autoreconf -i
e9014663 18$ ./configure && make && make install
19
20How to build on MSVC
21--------------------
22First you have to extract libfdk-aac source here, so that directory tree will
23look like the following:
24+- fdk-aac ---+-documentation
25| +-libAACdec
26| +-libAACenc
27| :
28+- m4
29+- missings
30+- MSVC
31+- src
32
33MSVC solution for Visual Studio 2010 is under MSVC directory.
a56831da 34
afe73f49 35Available input format
36----------------------
37WAV (or RF64), upto 32bit int / 64bit float format is supported.
38However, since FDK AAC encoder is implemented based on fixed point integer,
39encoder itself treats 16bit input only.
40Therefore, when feeding non-integer input, be careful so that input doesn't
41exceed 0dBFS to avoid hard clips.
42You might also want to apply dither/noise shape beforehand when your input
43has higher resolution.
44
45Note that fdkaac doesn't automatically resample for you
46when input samplerate is not supported by AAC spec.
47
a56831da 48Tagging Options
49---------------
50Generic tagging options like --tag, --tag-from-file, --long-tag allows you
51to set arbitrary tags.
52Available tags and their fcc (four char code) for --tag and --tag-from-file
53can be found at http://code.google.com/p/mp4v2/wiki/iTunesMetadata
54
55For tags such as Artist where first char of fcc is copyright sign,
56you can skip first char and just say like --tag="ART:Foo Bar" or
57--tag-from-file=lyr:/path/to/your/lyrics.txt
adbd1aac 58
59Currently, --tag-from-file just stores file contents into m4a without any
60character encoding / line terminater conversion.
61Therefore, only use UTF-8 (without BOM) when setting text tags by this option.
62
63On the other hand, --tag / --long-tag (and other command line arguments) are
64converted from locale character encoding to UTF-8 on Posix environment.
65On Windows, command line arguments are always treated as Unicode.
cbb23cdb 66
67Tagging using JSON
68------------------
69With --tag-from-json, fdkaac can read JSON file and set tags from it.
70By default, tags are assumed to be in the root object(dictionary) like this:
71
72{
73 "title": "No Expectations",
74 "artist": "The Rolling Stones",
75 "album": "Beggars Banquet",
76 "track": 2
77}
78
79In this case, you can simply specify the filename like:
80--tag-from-json=/path/to/json
81
82If the object containing tags is placed somewhere else, you can optionally
83specify the path of the object with dotted notation.
84
85{
86 "format" : {
87 "filename" : "Middle Curse.flac",
88 "nb_streams" : 1,
89 "format_name" : "flac",
90 "format_long_name" : "raw FLAC",
91 "start_time" : "N/A",
92 "duration" : "216.146667",
93 "size" : "11851007.000000",
94 "bit_rate" : "438628.000000",
95 "tags" : {
96 "ALBUM" : "Scary World Theory",
97 "ARTIST" : "Lali Puna",
98 "DATE" : "2001",
99 "DISCID" : "9208CC0A",
100 "TITLE" : "Middle Curse",
101 "TRACKTOTAL" : "10",
102 "track" : "2"
103 }
104 }
105}
106
107In 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").
109In this case, you can say:
110--tag-from-json=/path/to/json?format.tags
111
112For your information, ffprobe of ffmpeg project (or avprobe of libav) can
113output media information/metadata in json format like this.
114
115Note that not all tags can be read/written this way.
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