check_wav.c

   1 /*
   2  * Copyright (C) 2005-2013 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file check_wav.c Detect and delete a wav header. */
   8
   9 #include <regex.h>
  10
  11 #include "para.h"
  12 #include "string.h"
  13 #include "list.h"
  14 #include "sched.h"
  15 #include "buffer_tree.h"
  16 #include "error.h"
  17 #include "check_wav.h"
  18
  19 /** Length of a standard wav header. */
  20 #define WAV_HEADER_LEN 44
  21
  22 /** The possible states of a check_wav instance. */
  23 enum check_wav_state {
  24         /** Initial state, less than \p WAV_HEADER_LEN bytes available. */
  25         CWS_NEED_HEADER,
  26         /** Wav hader was detected. */
  27         CWS_HAVE_HEADER,
  28         /** First part of the stream did not look like a wav header. */
  29         CWS_NO_HEADER,
  30 };
  31
  32 struct check_wav_context {
  33         enum check_wav_state state;
  34         struct btr_node *btrn;
  35         size_t min_iqs;
  36         /* Command line args. */
  37         struct wav_params params;
  38         /* Extracted from the wav header.*/
  39         unsigned channels;
  40         unsigned sample_format;
  41         unsigned sample_rate;
  42 };
  43
  44 /**
  45  * Set select timeout according to the given context.
  46  *
  47  * \param s Contains the timeval that should be set.
  48  * \param cwc Contains a pointer to the buffer tree node.
  49  *
  50  * This requests a minimal timeout from the scheduler if btrn of \a cwc is not
  51  * idle.
  52  */
  53 void check_wav_pre_select(struct sched *s, struct check_wav_context *cwc)
  54 {
  55         int ret = btr_node_status(cwc->btrn, cwc->min_iqs, BTR_NT_INTERNAL);
  56         if (ret != 0)
  57                 sched_min_delay(s);
  58 }
  59
  60 static int check_wav_exec(struct btr_node *btrn, const char *cmd, char **result)
  61 {
  62         struct check_wav_context *cwc = btr_context(btrn);
  63         int val, header_val, given, arg;
  64
  65         header_val = cwc->channels;
  66         arg = cwc->params.channels_arg;
  67         given = cwc->params.channels_given;
  68         if (!strcmp(cmd, "channels"))
  69                 goto out;
  70
  71         header_val = cwc->sample_rate;
  72         arg = cwc->params.sample_rate_arg;
  73         given = cwc->params.sample_rate_given;
  74         if (!strcmp(cmd, "sample_rate"))
  75                 goto out;
  76
  77         header_val = cwc->sample_format;
  78         arg = cwc->params.sample_format_arg;
  79         given = cwc->params.sample_format_given;
  80         if (!strcmp(cmd, "sample_format"))
  81                 goto out;
  82
  83         return -ERRNO_TO_PARA_ERROR(ENOTSUP);
  84 out:
  85         if (given)
  86                 val = arg;
  87         else {
  88                 switch (cwc->state) {
  89                 case CWS_HAVE_HEADER:
  90                         val = header_val;
  91                         break;
  92                 case CWS_NO_HEADER:
  93                         /*
  94                          * No wav header available and no value specified at
  95                          * the command line. Maybe one of our parent nodes
  96                          * knows.
  97                          */
  98                         if (btr_exec_up(btr_parent(cwc->btrn), cmd, result) >= 0)
  99                                 return 1;
 100                         /* Use default value */
 101                         val = arg;
 102                         break;
 103                 default:
 104                         return -E_BTR_NAVAIL;
 105                 }
 106         }
 107         *result = make_message("%d", val);
 108         return 1;
 109 }
 110
 111 /**
 112  * Filter out the wav header, pushdown everything else.
 113  *
 114  * \param cwc The context of this instance.
 115  *
 116  * This function looks at the first \p WAV_HEADER_SIZE bytes of the input queue
 117  * of the btrn of \a cwc. If they look like a wav header, the function extracts
 118  * the information of interest and swallows this part of the stream. Otherwise
 119  * it is pushed down to all children of \a btrn. In either case the rest of the
 120  * input is pushed down as well.
 121  *
 122  * Once the first part has been processed this way, the state of the instance
 123  * changes from \p CWS_NEED_HEADER to \p CWS_HAVE_HEADER or \p CWS_NO_HEADER.
 124  *
 125  * \return Standard.
 126  */
 127 int check_wav_post_select(struct check_wav_context *cwc)
 128 {
 129         struct btr_node *btrn = cwc->btrn;
 130         unsigned char *a;
 131         size_t sz;
 132         int ret;
 133         uint16_t bps; /* bits per sample */
 134         const char *sample_formats[] = {SAMPLE_FORMATS};
 135
 136         if (!btrn)
 137                 return 0;
 138         ret = btr_node_status(btrn, cwc->min_iqs, BTR_NT_INTERNAL);
 139         if (ret <= 0)
 140                 goto out;
 141         if (cwc->state != CWS_NEED_HEADER)
 142                 goto pushdown;
 143         btr_merge(btrn, cwc->min_iqs);
 144         sz = btr_next_buffer(btrn, (char **)&a);
 145         if (sz < cwc->min_iqs) /* file size less than WAV_HEADER_SIZE */
 146                 goto pushdown;
 147         cwc->min_iqs = 0;
 148         /*
 149          * The default byte ordering assumed for WAVE data files is
 150          * little-endian. Files written using the big-endian byte ordering
 151          * scheme have the identifier RIFX instead of RIFF.
 152          */
 153         if (a[0] != 'R' || a[1] != 'I' || a[2] != 'F' ||
 154                         (a[3] != 'F' && a[3] != 'X')) {
 155                 PARA_NOTICE_LOG("wav header not found\n");
 156                 cwc->state = CWS_NO_HEADER;
 157                 goto out;
 158         }
 159         PARA_INFO_LOG("found wav header\n");
 160         cwc->state = CWS_HAVE_HEADER;
 161         /* Only set those values which have not already been set. */
 162         cwc->channels = (unsigned)a[22];
 163         cwc->sample_rate = a[24] + (a[25] << 8) + (a[26] << 16) + (a[27] << 24);
 164         bps = a[34] + ((unsigned)a[35] << 8);
 165         if (bps != 8 && bps != 16) {
 166                 PARA_WARNING_LOG("%u bps not supported, assuming 16\n",
 167                         bps);
 168                 bps = 16;
 169         }
 170         /*
 171          * 8-bit samples are stored as unsigned bytes, ranging from 0
 172          * to 255.  16-bit samples are stored as 2's-complement signed
 173          * integers, ranging from -32768 to 32767.
 174          */
 175         if (bps == 8)
 176                 cwc->sample_format = SF_U8;
 177         else
 178                 cwc->sample_format = (a[3] == 'F')?
 179                         SF_S16_LE : SF_S16_BE;
 180         PARA_NOTICE_LOG("%dHz, %s, %s\n", cwc->sample_rate,
 181                 cwc->channels == 1? "mono" : "stereo",
 182                 sample_formats[cwc->sample_format]);
 183         btr_consume(btrn, WAV_HEADER_LEN);
 184 pushdown:
 185         btr_pushdown(btrn);
 186 out:
 187         if (ret < 0)
 188                 btr_remove_node(&cwc->btrn);
 189         return ret;
 190 }
 191
 192 /**
 193  * Allocate and set up a new check_wav instance.
 194  *
 195  * \param parent This buffer tree node will be the parent of the new node.
 196  * \param child The child of the new node.
 197  * \param params Default values and options.
 198  * \param cw_btrn A pointer to the check wav node is returned here.
 199  *
 200  * This function also sets up the ->execute handler of the btrn so that all
 201  * children of this node can figure out channel count, sample rate, etc.
 202  *
 203  * \return The (opaque) handle of the newly created check_wav instance. It is
 204  * supposed to be passed to \ref check_wav_pre_select() and \ref
 205  * check_wav_post_select().
 206  *
 207  * \sa \ref btr_new_node.
 208  */
 209 struct check_wav_context *check_wav_init(struct btr_node *parent,
 210                 struct btr_node *child, struct wav_params *params,
 211                 struct btr_node **cw_btrn)
 212 {
 213         struct check_wav_context *cwc = para_calloc(sizeof(*cwc));
 214
 215         cwc->state = CWS_NEED_HEADER;
 216         cwc->min_iqs = WAV_HEADER_LEN;
 217         cwc->params = *params;
 218         cwc->btrn = btr_new_node(&(struct btr_node_description)
 219                 EMBRACE(.name = "check_wav", .parent = parent, .child = child,
 220                 .handler = check_wav_exec, .context = cwc));
 221         if (cw_btrn)
 222                 *cw_btrn = cwc->btrn;
 223         return cwc;
 224 }
 225
 226 /**
 227  * Dellocate all ressources of a check_wav instance.
 228  *
 229  * \param cwc Determines the instance to shut down.
 230  *
 231  * This function may only be called after check_wav_post_select() has returned
 232  * negative.
 233  */
 234 void check_wav_shutdown(struct check_wav_context *cwc)
 235 {
 236         free(cwc);
 237 }