209 lines
6.6 KiB
C
209 lines
6.6 KiB
C
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/* libdax_audioxtr
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Audio track data extraction facility of libdax and libburn.
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Copyright (C) 2006 Thomas Schmitt <scdbackup@gmx.net>, provided under GPL
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*/
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#ifndef LIBDAX_AUDIOXTR_H_INCLUDED
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#define LIBDAX_AUDIOXTR_H_INCLUDED 1
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/* Public Macros */
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/* Maximum size for address paths and fmt_info strings */
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#define LIBDAX_AUDIOXTR_STRLEN 4096
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/* Public Opaque Handles */
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/** Extractor object encapsulating intermediate states of extraction.
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The clients of libdax_audioxtr shall only allocate pointers to this
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struct and get a storage object via libdax_audioxtr_new().
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Appropriate initial value for the pointer is NULL.
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*/
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struct libdax_audioxtr;
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/* Public Functions */
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/* Calls initiated from inside libdax/libburn */
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/* Calls from applications (to be forwarded by libdax/libburn) */
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/** Open an audio file, check wether suitable, create extractor object.
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@param xtr Opaque handle to extractor. Gets attached extractor object.
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@param path Address of the audio file to extract. "-" is stdin (but might
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be not suitable for all futurely supported formats).
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@param flag Bitfield for control purposes (unused yet, submit 0)
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@return >0 success
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0 unsuitable format
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-1 severe error
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-2 path not found
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*/
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int libdax_audioxtr_new(struct libdax_audioxtr **xtr, char *path, int flag);
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/** Obtain identification parameters of opened audio source.
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@param xtr Opaque handle to extractor
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@param fmt Gets pointed to the audio file format id text: ".wav"
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@param fmt_info Gets pointed to a format info text telling parameters
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@param num_channels e.g. 1=mono, 2=stereo, etc
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@param sample_rate e.g. 11025, 44100
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@param bits_per_sample e.g. 8= 8 bits per sample, 16= 16 bits ...
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@param flag Bitfield for control purposes (unused yet, submit 0)
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@return >0 success, <=0 failure
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*/
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int libdax_audioxtr_get_id(struct libdax_audioxtr *xtr,
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char **fmt, char **fmt_info,
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int *num_channels, int *sample_rate,
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int *bits_per_sample, int flag);
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/** Obtain a prediction about the extracted size based on internal information
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of the formatted file.
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@param xtr Opaque handle to extractor
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@param size Gets filled with the predicted size
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@param flag Bitfield for control purposes (unused yet, submit 0)
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@return 1 prediction was possible , 0 no prediction could be made
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*/
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int libdax_audioxtr_get_size(struct libdax_audioxtr *o, off_t *size, int flag);
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/** Obtain next buffer full of extracted data in desired format (only raw audio
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for now).
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@param xtr Opaque handle to extractor
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@param buffer Gets filled with extracted data
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@param buffer_size Maximum number of bytes to be filled into buffer
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@param flag Bitfield for control purposes
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bit0= do not stop at predicted end of data
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@return >0 number of valid buffer bytes,
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0 End of file
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-1 operating system reports error
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-2 usage error by application
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*/
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int libdax_audioxtr_read(struct libdax_audioxtr *xtr,
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char buffer[], int buffer_size, int flag);
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/** Try to obtain a file descriptor which will deliver extracted data
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to normal calls of read(2). This may fail because the format is
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unsuitable for that, but ".wav" is ok. If this call succeeds the xtr
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object will have forgotten its file descriptor and libdax_audioxtr_read()
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will return a usage error. One may use *fd after libdax_audioxtr_destroy()
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and will have to close it via close(2) when done with it.
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@param xtr Opaque handle to extractor
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@param fd Eventually returns the file descriptor number
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@param flag Bitfield for control purposes
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bit0= do not dup(2) and close(2) but hand out original fd
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@return 1 success, 0 cannot hand out fd , -1 severe error
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*/
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int libdax_audioxtr_detach_fd(struct libdax_audioxtr *o, int *fd, int flag);
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/** Clean up after extraction and destroy extractor object.
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@param xtr Opaque handle to extractor, *xtr is allowed to be NULL,
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*xtr is set to NULL by this function
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@param flag Bitfield for control purposes (unused yet, submit 0)
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@return 1 = destroyed object, 0 = was already destroyed
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*/
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int libdax_audioxtr_destroy(struct libdax_audioxtr **xtr, int flag);
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#ifdef LIDBAX_AUDIOXTR________________
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-- place documentation text here ---
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#endif /* LIDBAX_AUDIOXTR_________________ */
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/*
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*Never* set this macro outside libdax_audioxtr.c !
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The entrails of this facility are not to be seen by
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the other library components or the applications.
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*/
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#ifdef LIBDAX_AUDIOXTR_H_INTERNAL
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/* Internal Structures */
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/** Extractor object encapsulating intermediate states of extraction */
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struct libdax_audioxtr {
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/* Source of the encoded audio data */
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char path[LIBDAX_AUDIOXTR_STRLEN];
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/* File descriptor to path */
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int fd;
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/* Format identifier. E.g. ".wav" */
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char fmt[80];
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/* Format parameter info text */
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char fmt_info[LIBDAX_AUDIOXTR_STRLEN];
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/* Number of bytes to extract (0= unknown/unlimited) */
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off_t data_size;
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/* Number of extracted data bytes */
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off_t extract_count;
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/* Format dependent parameters */
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/* MS WAVE Format */
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/* info used: http://ccrma.stanford.edu/courses/422/projects/WaveFormat/ */
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/* 1= mono, 2= stereo, etc. */
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int wav_num_channels;
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/* 8000, 44100, etc. */
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int wav_sample_rate;
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/* 8 bits = 8, 16 bits = 16, etc. */
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int wav_bits_per_sample;
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/* == NumSamples * NumChannels * BitsPerSample/8
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This is the number of bytes in the data. */
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unsigned wav_subchunk2_size;
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};
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/* Internal Functions */
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/** Open the audio source pointed to by .path and evaluate suitability.
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@return -1 failure to open, 0 unsuitable format, 1 success
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*/
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static int libdax_audioxtr_open(struct libdax_audioxtr *o, int flag);
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/** Identify format and evaluate suitability.
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@return 0 unsuitable format, 1 format is suitable
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*/
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static int libdax_audioxtr_identify(struct libdax_audioxtr *o, int flag);
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/** Convert a byte string into a number (currently only little endian)
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@return The resulting number
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*/
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static unsigned libdax_audioxtr_to_int(struct libdax_audioxtr *o,
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unsigned char *bytes, int len, int flag);
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/** Prepare for reading of first buffer.
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@return 0 error, 1 success
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*/
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static int libdax_audioxtr_init_reading(struct libdax_audioxtr *o, int flag);
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#endif /* LIBDAX_AUDIOXTR_H_INTERNAL */
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#endif /* ! LIBDAX_AUDIOXTR_H_INCLUDED */
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