frame.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief Frame and codec manipulation routines
 *
 * \author Mark Spencer <markster@digium.com> 
 */

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 334574 $")

#include "asterisk/_private.h"
#include "asterisk/lock.h"
#include "asterisk/frame.h"
#include "asterisk/channel.h"
#include "asterisk/cli.h"
#include "asterisk/term.h"
#include "asterisk/utils.h"
#include "asterisk/threadstorage.h"
#include "asterisk/linkedlists.h"
#include "asterisk/translate.h"
#include "asterisk/dsp.h"
#include "asterisk/file.h"

#if !defined(LOW_MEMORY)
static void frame_cache_cleanup(void *data);

/*! \brief A per-thread cache of frame headers */
AST_THREADSTORAGE_CUSTOM(frame_cache, NULL, frame_cache_cleanup);

/*! 
 * \brief Maximum ast_frame cache size
 *
 * In most cases where the frame header cache will be useful, the size
 * of the cache will stay very small.  However, it is not always the case that
 * the same thread that allocates the frame will be the one freeing them, so
 * sometimes a thread will never have any frames in its cache, or the cache
 * will never be pulled from.  For the latter case, we limit the maximum size. 
 */ 
#define FRAME_CACHE_MAX_SIZE  10

/*! \brief This is just so ast_frames, a list head struct for holding a list of
 *  ast_frame structures, is defined. */
AST_LIST_HEAD_NOLOCK(ast_frames, ast_frame);

struct ast_frame_cache {
   struct ast_frames list;
   size_t size;
};
#endif

#define SMOOTHER_SIZE 8000

enum frame_type {
   TYPE_HIGH,     /* 0x0 */
   TYPE_LOW,      /* 0x1 */
   TYPE_SILENCE,  /* 0x2 */
   TYPE_DONTSEND  /* 0x3 */
};

#define TYPE_MASK 0x3

struct ast_smoother {
   int size;
   struct ast_format format;
   int flags;
   float samplesperbyte;
   unsigned int opt_needs_swap:1;
   struct ast_frame f;
   struct timeval delivery;
   char data[SMOOTHER_SIZE];
   char framedata[SMOOTHER_SIZE + AST_FRIENDLY_OFFSET];
   struct ast_frame *opt;
   int len;
};

struct ast_frame ast_null_frame = { AST_FRAME_NULL, };

static int smoother_frame_feed(struct ast_smoother *s, struct ast_frame *f, int swap)
{
   if (s->flags & AST_SMOOTHER_FLAG_G729) {
      if (s->len % 10) {
         ast_log(LOG_NOTICE, "Dropping extra frame of G.729 since we already have a VAD frame at the end\n");
         return 0;
      }
   }
   if (swap) {
      ast_swapcopy_samples(s->data + s->len, f->data.ptr, f->samples);
   } else {
      memcpy(s->data + s->len, f->data.ptr, f->datalen);
   }
   /* If either side is empty, reset the delivery time */
   if (!s->len || ast_tvzero(f->delivery) || ast_tvzero(s->delivery)) { /* XXX really ? */
      s->delivery = f->delivery;
   }
   s->len += f->datalen;

   return 0;
}

void ast_smoother_reset(struct ast_smoother *s, int bytes)
{
   memset(s, 0, sizeof(*s));
   s->size = bytes;
}

void ast_smoother_reconfigure(struct ast_smoother *s, int bytes)
{
   /* if there is no change, then nothing to do */
   if (s->size == bytes) {
      return;
   }
   /* set the new desired output size */
   s->size = bytes;
   /* if there is no 'optimized' frame in the smoother,
    *   then there is nothing left to do
    */
   if (!s->opt) {
      return;
   }
   /* there is an 'optimized' frame here at the old size,
    * but it must now be put into the buffer so the data
    * can be extracted at the new size
    */
   smoother_frame_feed(s, s->opt, s->opt_needs_swap);
   s->opt = NULL;
}

struct ast_smoother *ast_smoother_new(int size)
{
   struct ast_smoother *s;
   if (size < 1)
      return NULL;
   if ((s = ast_malloc(sizeof(*s))))
      ast_smoother_reset(s, size);
   return s;
}

int ast_smoother_get_flags(struct ast_smoother *s)
{
   return s->flags;
}

void ast_smoother_set_flags(struct ast_smoother *s, int flags)
{
   s->flags = flags;
}

int ast_smoother_test_flag(struct ast_smoother *s, int flag)
{
   return (s->flags & flag);
}

int __ast_smoother_feed(struct ast_smoother *s, struct ast_frame *f, int swap)
{
   if (f->frametype != AST_FRAME_VOICE) {
      ast_log(LOG_WARNING, "Huh?  Can't smooth a non-voice frame!\n");
      return -1;
   }
   if (!s->format.id) {
      ast_format_copy(&s->format, &f->subclass.format);
      s->samplesperbyte = (float)f->samples / (float)f->datalen;
   } else if (ast_format_cmp(&s->format, &f->subclass.format) == AST_FORMAT_CMP_NOT_EQUAL) {
      ast_log(LOG_WARNING, "Smoother was working on %s format frames, now trying to feed %s?\n",
         ast_getformatname(&s->format), ast_getformatname(&f->subclass.format));
      return -1;
   }
   if (s->len + f->datalen > SMOOTHER_SIZE) {
      ast_log(LOG_WARNING, "Out of smoother space\n");
      return -1;
   }
   if (((f->datalen == s->size) ||
        ((f->datalen < 10) && (s->flags & AST_SMOOTHER_FLAG_G729))) &&
       !s->opt &&
       !s->len &&
       (f->offset >= AST_MIN_OFFSET)) {
      /* Optimize by sending the frame we just got
         on the next read, thus eliminating the douple
         copy */
      if (swap)
         ast_swapcopy_samples(f->data.ptr, f->data.ptr, f->samples);
      s->opt = f;
      s->opt_needs_swap = swap ? 1 : 0;
      return 0;
   }

   return smoother_frame_feed(s, f, swap);
}

struct ast_frame *ast_smoother_read(struct ast_smoother *s)
{
   struct ast_frame *opt;
   int len;

   /* IF we have an optimization frame, send it */
   if (s->opt) {
      if (s->opt->offset < AST_FRIENDLY_OFFSET)
         ast_log(LOG_WARNING, "Returning a frame of inappropriate offset (%d).\n",
                     s->opt->offset);
      opt = s->opt;
      s->opt = NULL;
      return opt;
   }

   /* Make sure we have enough data */
   if (s->len < s->size) {
      /* Or, if this is a G.729 frame with VAD on it, send it immediately anyway */
      if (!((s->flags & AST_SMOOTHER_FLAG_G729) && (s->len % 10)))
         return NULL;
   }
   len = s->size;
   if (len > s->len)
      len = s->len;
   /* Make frame */
   s->f.frametype = AST_FRAME_VOICE;
   ast_format_copy(&s->f.subclass.format, &s->format);
   s->f.data.ptr = s->framedata + AST_FRIENDLY_OFFSET;
   s->f.offset = AST_FRIENDLY_OFFSET;
   s->f.datalen = len;
   /* Samples will be improper given VAD, but with VAD the concept really doesn't even exist */
   s->f.samples = len * s->samplesperbyte;   /* XXX rounding */
   s->f.delivery = s->delivery;
   /* Fill Data */
   memcpy(s->f.data.ptr, s->data, len);
   s->len -= len;
   /* Move remaining data to the front if applicable */
   if (s->len) {
      /* In principle this should all be fine because if we are sending
         G.729 VAD, the next timestamp will take over anyawy */
      memmove(s->data, s->data + len, s->len);
      if (!ast_tvzero(s->delivery)) {
         /* If we have delivery time, increment it, otherwise, leave it at 0 */
         s->delivery = ast_tvadd(s->delivery, ast_samp2tv(s->f.samples, ast_format_rate(&s->format)));
      }
   }
   /* Return frame */
   return &s->f;
}

void ast_smoother_free(struct ast_smoother *s)
{
   ast_free(s);
}

static struct ast_frame *ast_frame_header_new(void)
{
   struct ast_frame *f;

#if !defined(LOW_MEMORY)
   struct ast_frame_cache *frames;

   if ((frames = ast_threadstorage_get(&frame_cache, sizeof(*frames)))) {
      if ((f = AST_LIST_REMOVE_HEAD(&frames->list, frame_list))) {
         size_t mallocd_len = f->mallocd_hdr_len;
         memset(f, 0, sizeof(*f));
         f->mallocd_hdr_len = mallocd_len;
         f->mallocd = AST_MALLOCD_HDR;
         frames->size--;
         return f;
      }
   }
   if (!(f = ast_calloc_cache(1, sizeof(*f))))
      return NULL;
#else
   if (!(f = ast_calloc(1, sizeof(*f))))
      return NULL;
#endif

   f->mallocd_hdr_len = sizeof(*f);
   
   return f;
}

#if !defined(LOW_MEMORY)
static void frame_cache_cleanup(void *data)
{
   struct ast_frame_cache *frames = data;
   struct ast_frame *f;

   while ((f = AST_LIST_REMOVE_HEAD(&frames->list, frame_list)))
      ast_free(f);
   
   ast_free(frames);
}
#endif

static void __frame_free(struct ast_frame *fr, int cache)
{
   if (!fr->mallocd)
      return;

#if !defined(LOW_MEMORY)
   if (cache && fr->mallocd == AST_MALLOCD_HDR) {
      /* Cool, only the header is malloc'd, let's just cache those for now 
       * to keep things simple... */
      struct ast_frame_cache *frames;

      if ((frames = ast_threadstorage_get(&frame_cache, sizeof(*frames))) &&
          (frames->size < FRAME_CACHE_MAX_SIZE)) {
         AST_LIST_INSERT_HEAD(&frames->list, fr, frame_list);
         frames->size++;
         return;
      }
   }
#endif
   
   if (fr->mallocd & AST_MALLOCD_DATA) {
      if (fr->data.ptr) 
         ast_free(fr->data.ptr - fr->offset);
   }
   if (fr->mallocd & AST_MALLOCD_SRC) {
      if (fr->src)
         ast_free((void *) fr->src);
   }
   if (fr->mallocd & AST_MALLOCD_HDR) {
      ast_free(fr);
   }
}


void ast_frame_free(struct ast_frame *frame, int cache)
{
   struct ast_frame *next;

   for (next = AST_LIST_NEXT(frame, frame_list);
        frame;
        frame = next, next = frame ? AST_LIST_NEXT(frame, frame_list) : NULL) {
      __frame_free(frame, cache);
   }
}

/*!
 * \brief 'isolates' a frame by duplicating non-malloc'ed components
 * (header, src, data).
 * On return all components are malloc'ed
 */
struct ast_frame *ast_frisolate(struct ast_frame *fr)
{
   struct ast_frame *out;
   void *newdata;

   /* if none of the existing frame is malloc'd, let ast_frdup() do it
      since it is more efficient
   */
   if (fr->mallocd == 0) {
      return ast_frdup(fr);
   }

   /* if everything is already malloc'd, we are done */
   if ((fr->mallocd & (AST_MALLOCD_HDR | AST_MALLOCD_SRC | AST_MALLOCD_DATA)) ==
       (AST_MALLOCD_HDR | AST_MALLOCD_SRC | AST_MALLOCD_DATA)) {
      return fr;
   }

   if (!(fr->mallocd & AST_MALLOCD_HDR)) {
      /* Allocate a new header if needed */
      if (!(out = ast_frame_header_new())) {
         return NULL;
      }
      out->frametype = fr->frametype;
      ast_format_copy(&out->subclass.format, &fr->subclass.format);
      out->datalen = fr->datalen;
      out->samples = fr->samples;
      out->offset = fr->offset;
      /* Copy the timing data */
      ast_copy_flags(out, fr, AST_FLAGS_ALL);
      if (ast_test_flag(fr, AST_FRFLAG_HAS_TIMING_INFO)) {
         out->ts = fr->ts;
         out->len = fr->len;
         out->seqno = fr->seqno;
      }
   } else {
      out = fr;
   }
   
   if (!(fr->mallocd & AST_MALLOCD_SRC) && fr->src) {
      if (!(out->src = ast_strdup(fr->src))) {
         if (out != fr) {
            ast_free(out);
         }
         return NULL;
      }
   } else {
      out->src = fr->src;
      fr->src = NULL;
      fr->mallocd &= ~AST_MALLOCD_SRC;
   }
   
   if (!(fr->mallocd & AST_MALLOCD_DATA))  {
      if (!fr->datalen) {
         out->data.uint32 = fr->data.uint32;
         out->mallocd = AST_MALLOCD_HDR | AST_MALLOCD_SRC;
         return out;
      }
      if (!(newdata = ast_malloc(fr->datalen + AST_FRIENDLY_OFFSET))) {
         if (out->src != fr->src) {
            ast_free((void *) out->src);
         }
         if (out != fr) {
            ast_free(out);
         }
         return NULL;
      }
      newdata += AST_FRIENDLY_OFFSET;
      out->offset = AST_FRIENDLY_OFFSET;
      out->datalen = fr->datalen;
      memcpy(newdata, fr->data.ptr, fr->datalen);
      out->data.ptr = newdata;
   } else {
      out->data = fr->data;
      memset(&fr->data, 0, sizeof(fr->data));
      fr->mallocd &= ~AST_MALLOCD_DATA;
   }

   out->mallocd = AST_MALLOCD_HDR | AST_MALLOCD_SRC | AST_MALLOCD_DATA;
   
   return out;
}

struct ast_frame *ast_frdup(const struct ast_frame *f)
{
   struct ast_frame *out = NULL;
   int len, srclen = 0;
   void *buf = NULL;

#if !defined(LOW_MEMORY)
   struct ast_frame_cache *frames;
#endif

   /* Start with standard stuff */
   len = sizeof(*out) + AST_FRIENDLY_OFFSET + f->datalen;
   /* If we have a source, add space for it */
   /*
    * XXX Watch out here - if we receive a src which is not terminated
    * properly, we can be easily attacked. Should limit the size we deal with.
    */
   if (f->src)
      srclen = strlen(f->src);
   if (srclen > 0)
      len += srclen + 1;
   
#if !defined(LOW_MEMORY)
   if ((frames = ast_threadstorage_get(&frame_cache, sizeof(*frames)))) {
      AST_LIST_TRAVERSE_SAFE_BEGIN(&frames->list, out, frame_list) {
         if (out->mallocd_hdr_len >= len) {
            size_t mallocd_len = out->mallocd_hdr_len;

            AST_LIST_REMOVE_CURRENT(frame_list);
            memset(out, 0, sizeof(*out));
            out->mallocd_hdr_len = mallocd_len;
            buf = out;
            frames->size--;
            break;
         }
      }
      AST_LIST_TRAVERSE_SAFE_END;
   }
#endif

   if (!buf) {
      if (!(buf = ast_calloc_cache(1, len)))
         return NULL;
      out = buf;
      out->mallocd_hdr_len = len;
   }

   out->frametype = f->frametype;
   ast_format_copy(&out->subclass.format, &f->subclass.format);
   out->datalen = f->datalen;
   out->samples = f->samples;
   out->delivery = f->delivery;
   /* Set us as having malloc'd header only, so it will eventually
      get freed. */
   out->mallocd = AST_MALLOCD_HDR;
   out->offset = AST_FRIENDLY_OFFSET;
   if (out->datalen) {
      out->data.ptr = buf + sizeof(*out) + AST_FRIENDLY_OFFSET;
      memcpy(out->data.ptr, f->data.ptr, out->datalen);  
   } else {
      out->data.uint32 = f->data.uint32;
   }
   if (srclen > 0) {
      /* This may seem a little strange, but it's to avoid a gcc (4.2.4) compiler warning */
      char *src;
      out->src = buf + sizeof(*out) + AST_FRIENDLY_OFFSET + f->datalen;
      src = (char *) out->src;
      /* Must have space since we allocated for it */
      strcpy(src, f->src);
   }
   ast_copy_flags(out, f, AST_FLAGS_ALL);
   out->ts = f->ts;
   out->len = f->len;
   out->seqno = f->seqno;
   return out;
}

void ast_swapcopy_samples(void *dst, const void *src, int samples)
{
   int i;
   unsigned short *dst_s = dst;
   const unsigned short *src_s = src;

   for (i = 0; i < samples; i++)
      dst_s[i] = (src_s[i]<<8) | (src_s[i]>>8);
}

/*! Dump a frame for debugging purposes */
void ast_frame_dump(const char *name, struct ast_frame *f, char *prefix)
{
   const char noname[] = "unknown";
   char ftype[40] = "Unknown Frametype";
   char cft[80];
   char subclass[40] = "Unknown Subclass";
   char csub[80];
   char moreinfo[40] = "";
   char cn[60];
   char cp[40];
   char cmn[40];
   const char *message = "Unknown";

   if (!name)
      name = noname;


   if (!f) {
      ast_verbose("%s [ %s (NULL) ] [%s]\n", 
         term_color(cp, prefix, COLOR_BRMAGENTA, COLOR_BLACK, sizeof(cp)),
         term_color(cft, "HANGUP", COLOR_BRRED, COLOR_BLACK, sizeof(cft)), 
         term_color(cn, name, COLOR_YELLOW, COLOR_BLACK, sizeof(cn)));
      return;
   }
   /* XXX We should probably print one each of voice and video when the format changes XXX */
   if (f->frametype == AST_FRAME_VOICE)
      return;
   if (f->frametype == AST_FRAME_VIDEO)
      return;
   switch(f->frametype) {
   case AST_FRAME_DTMF_BEGIN:
      strcpy(ftype, "DTMF Begin");
      subclass[0] = f->subclass.integer;
      subclass[1] = '\0';
      break;
   case AST_FRAME_DTMF_END:
      strcpy(ftype, "DTMF End");
      subclass[0] = f->subclass.integer;
      subclass[1] = '\0';
      break;
   case AST_FRAME_CONTROL:
      strcpy(ftype, "Control");
      switch (f->subclass.integer) {
      case AST_CONTROL_HANGUP:
         strcpy(subclass, "Hangup");
         break;
      case AST_CONTROL_RING:
         strcpy(subclass, "Ring");
         break;
      case AST_CONTROL_RINGING:
         strcpy(subclass, "Ringing");
         break;
      case AST_CONTROL_ANSWER:
         strcpy(subclass, "Answer");
         break;
      case AST_CONTROL_BUSY:
         strcpy(subclass, "Busy");
         break;
      case AST_CONTROL_TAKEOFFHOOK:
         strcpy(subclass, "Take Off Hook");
         break;
      case AST_CONTROL_OFFHOOK:
         strcpy(subclass, "Line Off Hook");
         break;
      case AST_CONTROL_CONGESTION:
         strcpy(subclass, "Congestion");
         break;
      case AST_CONTROL_FLASH:
         strcpy(subclass, "Flash");
         break;
      case AST_CONTROL_WINK:
         strcpy(subclass, "Wink");
         break;
      case AST_CONTROL_OPTION:
         strcpy(subclass, "Option");
         break;
      case AST_CONTROL_RADIO_KEY:
         strcpy(subclass, "Key Radio");
         break;
      case AST_CONTROL_RADIO_UNKEY:
         strcpy(subclass, "Unkey Radio");
         break;
      case AST_CONTROL_HOLD:
         strcpy(subclass, "Hold");
         break;
      case AST_CONTROL_UNHOLD:
         strcpy(subclass, "Unhold");
         break;
      case AST_CONTROL_T38_PARAMETERS:
         if (f->datalen != sizeof(struct ast_control_t38_parameters)) {
            message = "Invalid";
         } else {
            struct ast_control_t38_parameters *parameters = f->data.ptr;
            enum ast_control_t38 state = parameters->request_response;
            if (state == AST_T38_REQUEST_NEGOTIATE)
               message = "Negotiation Requested";
            else if (state == AST_T38_REQUEST_TERMINATE)
               message = "Negotiation Request Terminated";
            else if (state == AST_T38_NEGOTIATED)
               message = "Negotiated";
            else if (state == AST_T38_TERMINATED)
               message = "Terminated";
            else if (state == AST_T38_REFUSED)
               message = "Refused";
         }
         snprintf(subclass, sizeof(subclass), "T38_Parameters/%s", message);
         break;
      case -1:
         strcpy(subclass, "Stop generators");
         break;
      default:
         snprintf(subclass, sizeof(subclass), "Unknown control '%d'", f->subclass.integer);
      }
      break;
   case AST_FRAME_NULL:
      strcpy(ftype, "Null Frame");
      strcpy(subclass, "N/A");
      break;
   case AST_FRAME_IAX:
      /* Should never happen */
      strcpy(ftype, "IAX Specific");
      snprintf(subclass, sizeof(subclass), "IAX Frametype %d", f->subclass.integer);
      break;
   case AST_FRAME_TEXT:
      strcpy(ftype, "Text");
      strcpy(subclass, "N/A");
      ast_copy_string(moreinfo, f->data.ptr, sizeof(moreinfo));
      break;
   case AST_FRAME_IMAGE:
      strcpy(ftype, "Image");
      snprintf(subclass, sizeof(subclass), "Image format %s\n", ast_getformatname(&f->subclass.format));
      break;
   case AST_FRAME_HTML:
      strcpy(ftype, "HTML");
      switch (f->subclass.integer) {
      case AST_HTML_URL:
         strcpy(subclass, "URL");
         ast_copy_string(moreinfo, f->data.ptr, sizeof(moreinfo));
         break;
      case AST_HTML_DATA:
         strcpy(subclass, "Data");
         break;
      case AST_HTML_BEGIN:
         strcpy(subclass, "Begin");
         break;
      case AST_HTML_END:
         strcpy(subclass, "End");
         break;
      case AST_HTML_LDCOMPLETE:
         strcpy(subclass, "Load Complete");
         break;
      case AST_HTML_NOSUPPORT:
         strcpy(subclass, "No Support");
         break;
      case AST_HTML_LINKURL:
         strcpy(subclass, "Link URL");
         ast_copy_string(moreinfo, f->data.ptr, sizeof(moreinfo));
         break;
      case AST_HTML_UNLINK:
         strcpy(subclass, "Unlink");
         break;
      case AST_HTML_LINKREJECT:
         strcpy(subclass, "Link Reject");
         break;
      default:
         snprintf(subclass, sizeof(subclass), "Unknown HTML frame '%d'\n", f->subclass.integer);
         break;
      }
      break;
   case AST_FRAME_MODEM:
      strcpy(ftype, "Modem");
      switch (f->subclass.integer) {
      case AST_MODEM_T38:
         strcpy(subclass, "T.38");
         break;
      case AST_MODEM_V150:
         strcpy(subclass, "V.150");
         break;
      default:
         snprintf(subclass, sizeof(subclass), "Unknown MODEM frame '%d'\n", f->subclass.integer);
         break;
      }
      break;
   default:
      snprintf(ftype, sizeof(ftype), "Unknown Frametype '%d'", f->frametype);
   }
   if (!ast_strlen_zero(moreinfo))
      ast_verbose("%s [ TYPE: %s (%d) SUBCLASS: %s (%d) '%s' ] [%s]\n",  
             term_color(cp, prefix, COLOR_BRMAGENTA, COLOR_BLACK, sizeof(cp)),
             term_color(cft, ftype, COLOR_BRRED, COLOR_BLACK, sizeof(cft)),
             f->frametype, 
             term_color(csub, subclass, COLOR_BRCYAN, COLOR_BLACK, sizeof(csub)),
             f->subclass.integer, 
             term_color(cmn, moreinfo, COLOR_BRGREEN, COLOR_BLACK, sizeof(cmn)),
             term_color(cn, name, COLOR_YELLOW, COLOR_BLACK, sizeof(cn)));
   else
      ast_verbose("%s [ TYPE: %s (%d) SUBCLASS: %s (%d) ] [%s]\n",  
             term_color(cp, prefix, COLOR_BRMAGENTA, COLOR_BLACK, sizeof(cp)),
             term_color(cft, ftype, COLOR_BRRED, COLOR_BLACK, sizeof(cft)),
             f->frametype, 
             term_color(csub, subclass, COLOR_BRCYAN, COLOR_BLACK, sizeof(csub)),
             f->subclass.integer, 
             term_color(cn, name, COLOR_YELLOW, COLOR_BLACK, sizeof(cn)));
}

int ast_parse_allow_disallow(struct ast_codec_pref *pref, struct ast_format_cap *cap, const char *list, int allowing) 
{
   int errors = 0, framems = 0, all = 0, iter_allowing;
   char *parse = NULL, *this = NULL, *psize = NULL;
   struct ast_format format;

   parse = ast_strdupa(list);
   while ((this = strsep(&parse, ","))) {
      iter_allowing = allowing;
      framems = 0;
      if (*this == '!') {
         this++;
         iter_allowing = !allowing;
      }
      if ((psize = strrchr(this, ':'))) {
         *psize++ = '\0';
         ast_debug(1, "Packetization for codec: %s is %s\n", this, psize);
         framems = atoi(psize);
         if (framems < 0) {
            framems = 0;
            errors++;
            ast_log(LOG_WARNING, "Bad packetization value for codec %s\n", this);
         }
      }
      all = strcasecmp(this, "all") ? 0 : 1;

      if (!all && !ast_getformatbyname(this, &format)) {
         ast_log(LOG_WARNING, "Cannot %s unknown format '%s'\n", iter_allowing ? "allow" : "disallow", this);
         errors++;
         continue;
      }

      if (cap) {
         if (iter_allowing) {
            if (all) {
               ast_format_cap_add_all(cap);
            } else {
               ast_format_cap_add(cap, &format);
            }
         } else {
            if (all) {
               ast_format_cap_remove_all(cap);
            } else {
               ast_format_cap_remove(cap, &format);
            }
         }
      }

      if (pref) {
         if (!all) {
            if (iter_allowing) {
               ast_codec_pref_append(pref, &format);
               ast_codec_pref_setsize(pref, &format, framems);
            } else {
               ast_codec_pref_remove(pref, &format);
            }
         } else if (!iter_allowing) {
            memset(pref, 0, sizeof(*pref));
         }
      }
   }
   return errors;
}

static int g723_len(unsigned char buf)
{
   enum frame_type type = buf & TYPE_MASK;

   switch(type) {
   case TYPE_DONTSEND:
      return 0;
      break;
   case TYPE_SILENCE:
      return 4;
      break;
   case TYPE_HIGH:
      return 24;
      break;
   case TYPE_LOW:
      return 20;
      break;
   default:
      ast_log(LOG_WARNING, "Badly encoded frame (%d)\n", type);
   }
   return -1;
}

static int g723_samples(unsigned char *buf, int maxlen)
{
   int pos = 0;
   int samples = 0;
   int res;
   while(pos < maxlen) {
      res = g723_len(buf[pos]);
      if (res <= 0)
         break;
      samples += 240;
      pos += res;
   }
   return samples;
}

static unsigned char get_n_bits_at(unsigned char *data, int n, int bit)
{
   int byte = bit / 8;       /* byte containing first bit */
   int rem = 8 - (bit % 8);  /* remaining bits in first byte */
   unsigned char ret = 0;
   
   if (n <= 0 || n > 8)
      return 0;

   if (rem < n) {
      ret = (data[byte] << (n - rem));
      ret |= (data[byte + 1] >> (8 - n + rem));
   } else {
      ret = (data[byte] >> (rem - n));
   }

   return (ret & (0xff >> (8 - n)));
}

static int speex_get_wb_sz_at(unsigned char *data, int len, int bit)
{
   static const int SpeexWBSubModeSz[] = {
      4, 36, 112, 192,
      352, 0, 0, 0 };
   int off = bit;
   unsigned char c;

   /* skip up to two wideband frames */
   if (((len * 8 - off) >= 5) && 
      get_n_bits_at(data, 1, off)) {
      c = get_n_bits_at(data, 3, off + 1);
      off += SpeexWBSubModeSz[c];

      if (((len * 8 - off) >= 5) && 
         get_n_bits_at(data, 1, off)) {
         c = get_n_bits_at(data, 3, off + 1);
         off += SpeexWBSubModeSz[c];

         if (((len * 8 - off) >= 5) && 
            get_n_bits_at(data, 1, off)) {
            ast_log(LOG_WARNING, "Encountered corrupt speex frame; too many wideband frames in a row.\n");
            return -1;
         }
      }

   }
   return off - bit;
}

static int speex_samples(unsigned char *data, int len)
{
   static const int SpeexSubModeSz[] = {
      5, 43, 119, 160,
      220, 300, 364, 492, 
      79, 0, 0, 0,
      0, 0, 0, 0 };
   static const int SpeexInBandSz[] = { 
      1, 1, 4, 4,
      4, 4, 4, 4,
      8, 8, 16, 16,
      32, 32, 64, 64 };
   int bit = 0;
   int cnt = 0;
   int off;
   unsigned char c;

   while ((len * 8 - bit) >= 5) {
      /* skip wideband frames */
      off = speex_get_wb_sz_at(data, len, bit);
      if (off < 0)  {
         ast_log(LOG_WARNING, "Had error while reading wideband frames for speex samples\n");
         break;
      }
      bit += off;

      if ((len * 8 - bit) < 5)
         break;

      /* get control bits */
      c = get_n_bits_at(data, 5, bit);
      bit += 5;

      if (c == 15) { 
         /* terminator */
         break; 
      } else if (c == 14) {
         /* in-band signal; next 4 bits contain signal id */
         c = get_n_bits_at(data, 4, bit);
         bit += 4;
         bit += SpeexInBandSz[c];
      } else if (c == 13) {
         /* user in-band; next 4 bits contain msg len */
         c = get_n_bits_at(data, 4, bit);
         bit += 4;
         /* after which it's 5-bit signal id + c bytes of data */
         bit += 5 + c * 8;
      } else if (c > 8) {
         /* unknown */
         ast_log(LOG_WARNING, "Unknown speex control frame %d\n", c);
         break;
      } else {
         /* skip number bits for submode (less the 5 control bits) */
         bit += SpeexSubModeSz[c] - 5;
         cnt += 160; /* new frame */
      }
   }
   return cnt;
}

int ast_codec_get_samples(struct ast_frame *f)
{
   int samples = 0;

   switch (f->subclass.format.id) {
   case AST_FORMAT_SPEEX:
      samples = speex_samples(f->data.ptr, f->datalen);
      break;
   case AST_FORMAT_SPEEX16:
      samples = 2 * speex_samples(f->data.ptr, f->datalen);
      break;
   case AST_FORMAT_SPEEX32:
      samples = 4 * speex_samples(f->data.ptr, f->datalen);
      break;
   case AST_FORMAT_G723_1:
      samples = g723_samples(f->data.ptr, f->datalen);
      break;
   case AST_FORMAT_ILBC:
      samples = 240 * (f->datalen / 50);
      break;
   case AST_FORMAT_GSM:
      samples = 160 * (f->datalen / 33);
      break;
   case AST_FORMAT_G729A:
      samples = f->datalen * 8;
      break;
   case AST_FORMAT_SLINEAR:
   case AST_FORMAT_SLINEAR16:
      samples = f->datalen / 2;
      break;
   case AST_FORMAT_LPC10:
      /* assumes that the RTP packet contains one LPC10 frame */
      samples = 22 * 8;
      samples += (((char *)(f->data.ptr))[7] & 0x1) * 8;
      break;
   case AST_FORMAT_ULAW:
   case AST_FORMAT_ALAW:
   case AST_FORMAT_TESTLAW:
      samples = f->datalen;
      break;
   case AST_FORMAT_G722:
   case AST_FORMAT_ADPCM:
   case AST_FORMAT_G726:
   case AST_FORMAT_G726_AAL2:
      samples = f->datalen * 2;
      break;
   case AST_FORMAT_SIREN7:
      /* 16,000 samples per second at 32kbps is 4,000 bytes per second */
      samples = f->datalen * (16000 / 4000);
      break;
   case AST_FORMAT_SIREN14:
      /* 32,000 samples per second at 48kbps is 6,000 bytes per second */
      samples = (int) f->datalen * ((float) 32000 / 6000);
      break;
   case AST_FORMAT_G719:
      /* 48,000 samples per second at 64kbps is 8,000 bytes per second */
      samples = (int) f->datalen * ((float) 48000 / 8000);
      break;
   case AST_FORMAT_SILK:
      if (!(ast_format_isset(&f->subclass.format,
         SILK_ATTR_KEY_SAMP_RATE,
         SILK_ATTR_VAL_SAMP_24KHZ,
         AST_FORMAT_ATTR_END))) {
         return 480;
      } else if (!(ast_format_isset(&f->subclass.format,
         SILK_ATTR_KEY_SAMP_RATE,
         SILK_ATTR_VAL_SAMP_16KHZ,
         AST_FORMAT_ATTR_END))) {
         return 320;
      } else if (!(ast_format_isset(&f->subclass.format,
         SILK_ATTR_KEY_SAMP_RATE,
         SILK_ATTR_VAL_SAMP_12KHZ,
         AST_FORMAT_ATTR_END))) {
         return 240;
      } else {
         return 160;
      }
   case AST_FORMAT_CELT:
      /* TODO The assumes 20ms delivery right now, which is incorrect */
      samples = ast_format_rate(&f->subclass.format) / 50;
      break;
   default:
      ast_log(LOG_WARNING, "Unable to calculate samples for format %s\n", ast_getformatname(&f->subclass.format));
   }
   return samples;
}

int ast_codec_get_len(struct ast_format *format, int samples)
{
   int len = 0;

   /* XXX Still need speex, and lpc10 XXX */ 
   switch(format->id) {
   case AST_FORMAT_G723_1:
      len = (samples / 240) * 20;
      break;
   case AST_FORMAT_ILBC:
      len = (samples / 240) * 50;
      break;
   case AST_FORMAT_GSM:
      len = (samples / 160) * 33;
      break;
   case AST_FORMAT_G729A:
      len = samples / 8;
      break;
   case AST_FORMAT_SLINEAR:
   case AST_FORMAT_SLINEAR16:
      len = samples * 2;
      break;
   case AST_FORMAT_ULAW:
   case AST_FORMAT_ALAW:
   case AST_FORMAT_TESTLAW:
      len = samples;
      break;
   case AST_FORMAT_G722:
   case AST_FORMAT_ADPCM:
   case AST_FORMAT_G726:
   case AST_FORMAT_G726_AAL2:
      len = samples / 2;
      break;
   case AST_FORMAT_SIREN7:
      /* 16,000 samples per second at 32kbps is 4,000 bytes per second */
      len = samples / (16000 / 4000);
      break;
   case AST_FORMAT_SIREN14:
      /* 32,000 samples per second at 48kbps is 6,000 bytes per second */
      len = (int) samples / ((float) 32000 / 6000);
      break;
   case AST_FORMAT_G719:
      /* 48,000 samples per second at 64kbps is 8,000 bytes per second */
      len = (int) samples / ((float) 48000 / 8000);
      break;
   default:
      ast_log(LOG_WARNING, "Unable to calculate sample length for format %s\n", ast_getformatname(format));
   }

   return len;
}

int ast_frame_adjust_volume(struct ast_frame *f, int adjustment)
{
   int count;
   short *fdata = f->data.ptr;
   short adjust_value = abs(adjustment);

   if ((f->frametype != AST_FRAME_VOICE) || !(ast_format_is_slinear(&f->subclass.format))) {
      return -1;
   }

   if (!adjustment) {
      return 0;
   }

   for (count = 0; count < f->samples; count++) {
      if (adjustment > 0) {
         ast_slinear_saturated_multiply(&fdata[count], &adjust_value);
      } else if (adjustment < 0) {
         ast_slinear_saturated_divide(&fdata[count], &adjust_value);
      }
   }

   return 0;
}

int ast_frame_slinear_sum(struct ast_frame *f1, struct ast_frame *f2)
{
   int count;
   short *data1, *data2;

   if ((f1->frametype != AST_FRAME_VOICE) || (f1->subclass.format.id != AST_FORMAT_SLINEAR))
      return -1;

   if ((f2->frametype != AST_FRAME_VOICE) || (f2->subclass.format.id != AST_FORMAT_SLINEAR))
      return -1;

   if (f1->samples != f2->samples)
      return -1;

   for (count = 0, data1 = f1->data.ptr, data2 = f2->data.ptr;
        count < f1->samples;
        count++, data1++, data2++)
      ast_slinear_saturated_add(data1, data2);

   return 0;
}

int ast_frame_clear(struct ast_frame *frame)
{
   struct ast_frame *next;

   for (next = AST_LIST_NEXT(frame, frame_list);
       frame;
       frame = next, next = frame ? AST_LIST_NEXT(frame, frame_list) : NULL) {
      memset(frame->data.ptr, 0, frame->datalen);
   }
   return 0;
}