afh.h

   1 /*
   2  * Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file afh.h Structures for audio format handling (para_server). */
   8
   9 /**
  10  * The tags used by all audio format handlers.
  11  *
  12  * Paraslash only uses the more common tags. These are recognized
  13  * for all supported audio formats.
  14  */
  15 struct taginfo {
  16         /** TPE1 (id3v2) / ARTIST (vorbis) / ART (aac)/ author(spx) */
  17         char *artist;
  18         /** TIT2/TITLE/nam */
  19         char *title;
  20         /** TDRC/YEAR/day */
  21         char *year;
  22         /** TALB/ALBUM/alb */
  23         char *album;
  24         /** COMM/COMMENT/cmt */
  25         char *comment;
  26 };
  27
  28 /** Audio format dependent information. */
  29 struct afh_info {
  30         /** The number of chunks this audio file contains. */
  31         long unsigned chunks_total;
  32         /** The length of the audio file in seconds. */
  33         long unsigned seconds_total;
  34         /** Audio handler specific info about the file. */
  35         char *techinfo;
  36         /** Id3 tags, vorbis comments, aac tags. */
  37         struct taginfo tags;
  38         /**
  39          * The table that specifies the offset of the individual pieces in
  40          * the current audio file.
  41          */
  42         uint32_t *chunk_table;
  43         /** Period of time between sending data chunks. */
  44         struct timeval chunk_tv;
  45         /**
  46          * The header is needed by senders in case a new client connects in the
  47          * middle of the stream. The length of the header defaults to zero
  48          * which means that this audio format does not need any special header
  49          * treatment. The audio format handler does not need to set this to
  50          * zero in this case.
  51          */
  52         uint32_t header_len;
  53         /** The number of channels. */
  54         uint8_t channels;
  55         /** Frequency in Hz. */
  56         uint16_t frequency;
  57         /** Exact meaning depends on audio format. */
  58         uint16_t bitrate;
  59 };
  60
  61 /** Data about the current audio file, passed from afs to server. */
  62 struct audio_file_data {
  63         /** The open file descriptor to the current audio file. */
  64         int fd;
  65         /** Vss needs this for streaming. */
  66         struct afh_info afhi;
  67         /** Size of the largest chunk. */
  68         uint32_t max_chunk_size;
  69         /** Needed to get the audio file header. */
  70         uint8_t audio_format_id;
  71 };
  72
  73 /**
  74  * Structure for audio format handling.
  75  *
  76  * There's one such struct for each supported audio format. Initially, only \a
  77  * name and \a init are defined. During the startup process, para_server calls
  78  * the \a init function of each audio format handler which is expected to fill
  79  * in the other part of this struct.
  80  */
  81 struct audio_format_handler {
  82         /** Name of the audio format. */
  83         const char *name;
  84         /**
  85          * Pointer to the audio format handler's init function.
  86          *
  87          * Must initialize all function pointers and is assumed to succeed.
  88          */
  89         void (*init)(struct audio_format_handler*);
  90         /** Typical file endings for files that can be handled by this afh. */
  91         const char **suffixes;
  92         /**
  93          * Check if this audio format handler can handle the file.
  94          *
  95          * This is a pointer to a function returning whether a given file is
  96          * valid for this audio format. A negative return value indicates that
  97          * this audio format handler is unable to decode the given file. On
  98          * success, the function must return a positive value and fill in the
  99          * given struct afh_info.
 100          *
 101          * \sa struct afh_info
 102          */
 103         int (*get_file_info)(char *map, size_t numbytes, int fd,
 104                 struct afh_info *afi);
 105         /** Optional, used for header-rewriting. See \ref afh_get_header(). */
 106         void (*get_header)(void *map, size_t mapsize, char **buf, size_t *len);
 107         /**
 108          * Write audio file with altered tags, optional.
 109          *
 110          * The output file descriptor has been opened by the caller and must not
 111          * be closed in this function.
 112          */
 113         int (*rewrite_tags)(const char *map, size_t mapsize, struct taginfo *tags,
 114                 int output_fd, const char *filename);
 115 };
 116
 117 void afh_init(void);
 118 int guess_audio_format(const char *name);
 119 int compute_afhi(const char *path, char *data, size_t size,
 120         int fd, struct afh_info *afhi);
 121 const char *audio_format_name(int);
 122 void afh_get_chunk(long unsigned chunk_num, struct afh_info *afhi,
 123                 void *map, const char **buf, size_t *len);
 124 int32_t afh_get_start_chunk(int32_t approx_chunk_num,
 125                 const struct afh_info *afhi);
 126 void afh_get_header(struct afh_info *afhi, uint8_t audio_format_id,
 127                 void *map, size_t mapsize, char **buf, size_t *len);
 128 void afh_free_header(char *header_buf, uint8_t audio_format_id);
 129 void clear_afhi(struct afh_info *afhi);
 130 unsigned afh_get_afhi_txt(int audio_format_num, struct afh_info *afhi, char **result);
 131 int afh_rewrite_tags(int audio_format_id, void *map, size_t mapsize,
 132                 struct taginfo *tags, int output_fd, const char *filename);