afconvert iPhone参考库

Question

您能否介绍一些关于在iPhone中使用afconvert转换文件格式的信息？ 或让我知道一些链接，给我关于afconvert的基本信息。我想知道使用的命令 - 什么做-f，-d，-c等代表在：

afconvert -f aac -d mp3 [input] [output]

在哪里注明出处的数据格式，文件格式和目标数据格式，上述命令中的文件格式？

Answer 1

afconvert -h

在终端迅速产生，在10.6.6：

afconvert [option...] input_file [output_file] 
    Options may appear before or after the direct arguments. If output_file 
    is not specified, a name is generated programmatically and the file 
    is written into the same directory as input_file. 
afconvert input_file [-o output_file [option...]]... 
    Output file options apply to the previous output_file. Other options 
    may appear anywhere. 

General options: 
    { -d | --data } data_format[@sample_rate][/format_flags][#frames_per_packet] 
     [-][BE|LE]{F|[U]I}{8|16|24|32|64}   (PCM) 
      e.g. BEI16 F32@44100 
     or a data format appropriate to file format (see -hf) 
     format_flags: hex digits, e.g. '80' 
     Frames per packet can be specified for some encoders, e.g.: samr#12 
     A format of "0" specifies the same format as the source file, 
      with packets copied exactly. 
    { -c | --channels } number_of_channels 
     add/remove channels without regard to order 
    { -l | --channellayout } layout_tag 
     layout_tag: name of a constant from CoreAudioTypes.h 
      (prefix "kAudioChannelLayoutTag_" may be omitted) 
     if specified once, applies to output file; if twice, the first 
      applies to the input file, the second to the output file 
    { -b | --bitrate } total_bit_rate_bps 
     e.g. 256000 will give you roughly: 
      for stereo source: 128000 bits per channel 
      for 5.1 source: 51000 bits per channel 
       (the .1 channel consumes few bits and can be discounted in the total bit rate calculation) 
    { -q | --quality } codec_quality 
     codec_quality: 0-127 
    { -r | --src-quality } src_quality 
     src_quality (sample rate converter quality): 0-127 (default is 127) 
    { --src-complexity } src_complexity 
     src_complexity (sample rate converter complexity): line, norm, bats 
    { -s | --strategy } strategy 
     bitrate allocation strategy for encoding an audio track 
     0 for CBR, 1 for ABR, 2 for VBR_constrained, 3 for VBR 
    --prime-method method 
     decode priming method (see AudioConverter.h) 
    --no-filler 
     don't page-align audio data in the output file 
    --soundcheck-generate 
     analyze audio, add SoundCheck data to the output file 
    { -u | --userproperty } property value 
     set an arbitrary AudioConverter property to a given value 
     property is a four-character code; value is signed 32-bit integer. 
     A maximum of 8 properties may be set. 
     e.g. '-u vbrq <sound_quality>' sets the sound quality level 
      (<sound_quality>: 0-127) 

Input file options: 
    --read-track track_index 
     For input files containing multiple tracks, the index (0..n-1) 
     of the track to read and convert. 
    --offset number_of_frames 
     the starting offset in the input file in frames. (The first frame is 
     frame zero.) 
    --soundcheck-read 
     read SoundCheck data from source file and set it on any destination 
     file(s) of appropriate filetype (.m4a, .caf). 

Output file options: 
    -o filename 
     specify an (additional) output file. 
    { -f | --file } file_format 
     use -hf for a complete list of supported file/data formats 

Other options: 
    { -v | --verbose } 
     print progress verbosely 
    { -t | --tag } 
     If encoding to CAF, store the source file's format and name in a user 
     chunk. If decoding from CAF, use the destination format and filename 
     found in a user chunk. 
    { --leaks } 
     run leaks at the end of the conversion 
    { --profile } 
     collect and print performance information 

Help options: 
    { -hf | --help-formats } 
     print a list of supported file/data formats 
    { -h | --help } 
     print this help