mad 0.5.2 · OCaml Package

* Functions for decoding mp3 files using the libmad. * *

author Samuel Mimram

Exceptions

exception Mad_error of string

An error occured with libmad.

exception Read_error of string

An error occured while reading a file.

exception End_of_stream

The end of the mp3 stream was reached.

exception Openfile_error of string

Could not open a file.

exception Closefile_error of string

Could not close a file.

Decoding files

type mad_file

An mp3 file opened for decoding.

type mpeg_layer =

| Layer_I
| Layer_II
| Layer_III

type emphasis =

| None
| MS_50_15
| CCITT_J_17
| Reserved

type channel_mode =

| Single_channel
| Dual_channel
| Joint_stereo
| Stereo

type frame_format = {

layer : mpeg_layer;
mode : channel_mode;
emphasis : emphasis;
bitrate : int;
samplerate : int;
channels : int;
samples_per_channel : int;
original : bool;
copyright : bool;
private_bit : bool;

}

type read = bytes -> int -> int -> int

Type for abstract reader.

val openfile : string -> mad_file

* Open an mp3 file. * *

raises Openfile_error
if an error occured while trying to open the file.

val openstream : read -> mad_file

* openstream read_func opens a stream where read_func n should be a * function which returns n bytes of data or less, the second component of * the result being the number of bytes to read in the fist component.

val skip_id3tags : read:read -> seek:(int -> int) -> tell:(unit -> int) -> unit

* Skip ID3 tags that may be present at * the beginning of a stream. This function * may be used to a mp3 file opened using openstream. * ID3 tags are always skipped when using openfile. * * seek is a callback to seek to an absolute * position on the encoded data, and tell a callback * to fetch the current position. read is the reading * callback.

val close : mad_file -> unit

* Close an mp3 file previously opened with openfile. * *

raises Closefile_error
if an error occured while trying to close the file.

val get_current_position : mad_file -> int

* Get the current position (in bytes) of the decoder in the mp3 file which * should have been opened with openfile.

type time_unit =

| Hours
| Minutes
| Seconds
| Deciseconds
| Centiseconds
| Milliseconds

val get_current_time : mad_file -> time_unit -> int

* Get the current time position (in the given unit) of the decoder.

val decode_frame : mad_file -> string

Decode an mp3 frame. * Returned data in interleaved when * there are two channels, and mono data * when there is only one.

val decode_frame_float : mad_file -> float array array

Decode an mp3 frame.

val decode_frame_float_ba : 
  mad_file ->
  (float, Bigarray.float32_elt, Bigarray.c_layout) Bigarray.Array1.t array

val skip_frame : mad_file -> unit

Skip one frame. The current time/position is * updated but the frame is not decoded.

val get_frame_format : mad_file -> frame_format

val get_output_format : mad_file -> int * int * int

val duration : string -> float

Compute the duration of a file, in seconds. * Never raises any exception, but returns 0. in case of error.

package mad

Exceptions

Decoding files