yuv4mpeg.c

Motion JPEG编解码器源代码

y4m_xtag_list_t *y4m_si_xtags(y4m_stream_info_t *si)
{ return &(si->x_tags); }



void y4m_init_frame_info(y4m_frame_info_t *info)
{
  if (info == NULL) return;
  /* init substructures */
  y4m_init_xtag_list(&(info->x_tags));
  /* set defaults */
  y4m_clear_frame_info(info);
}


void y4m_clear_frame_info(y4m_frame_info_t *info)
{
  if (info == NULL) return;
  /* clear/initialize info */
  info->spatial = Y4M_UNKNOWN;
  info->temporal = Y4M_UNKNOWN;
  info->presentation = Y4M_UNKNOWN;
  y4m_xtag_clearlist(&(info->x_tags));
}


void y4m_copy_frame_info(y4m_frame_info_t *dest, const y4m_frame_info_t *src)
{
  if ((dest == NULL) || (src == NULL)) return;
  /* copy info */
  dest->spatial = src->spatial;
  dest->temporal = src->temporal;
  dest->presentation = src->presentation;
  y4m_copy_xtag_list(&(dest->x_tags), &(src->x_tags));
}

void y4m_fini_frame_info(y4m_frame_info_t *info)
{
  if (info == NULL) return;
  y4m_fini_xtag_list(&(info->x_tags));
}


void y4m_fi_set_presentation(y4m_frame_info_t *fi, int pres)
{ fi->presentation = pres; }

int y4m_fi_get_presentation(const y4m_frame_info_t *fi)
{ return fi->presentation; }

void y4m_fi_set_temporal(y4m_frame_info_t *fi, int sampling)
{ fi->temporal = sampling; }

int y4m_fi_get_temporal(const y4m_frame_info_t *fi)
{ return fi->temporal; }

void y4m_fi_set_spatial(y4m_frame_info_t *fi, int sampling)
{ fi->spatial = sampling; }

int y4m_fi_get_spatial(const y4m_frame_info_t *fi)
{ return fi->spatial; }



y4m_xtag_list_t *y4m_fi_xtags(y4m_frame_info_t *fi)
{ return &(fi->x_tags); }


/*************************************************************************
 *
 * Tag parsing 
 *
 *************************************************************************/


/* Parse (the first) old, unofficial X-tag chroma specification,
   and then remove that tag from the X-tag list. */
static int
handle_old_chroma_xtag(y4m_stream_info_t *si)
{
  y4m_xtag_list_t *xtags = y4m_si_xtags(si);
  const char *tag = NULL;
  int n, chroma;

  for (n = y4m_xtag_count(xtags) - 1; n >= 0; n--) {
    tag = y4m_xtag_get(xtags, n);
    if (!strncmp("XYSCSS=", tag, 7)) break;
  }
  if ((tag == NULL) || (n < 0)) return Y4M_UNKNOWN;
  mjpeg_warn("Deprecated X-tag for chroma found in a stream header...");
  mjpeg_warn("...pester someone to upgrade the source's program!");
  /* parse the tag */
  tag += 7;
  if (!strcmp("411", tag))           chroma = Y4M_CHROMA_411;
  else if (!strcmp(tag, "420"))      chroma = Y4M_CHROMA_420JPEG;
  else if (!strcmp(tag, "420MPEG2")) chroma = Y4M_CHROMA_420MPEG2;
  else if (!strcmp(tag, "420PALDV")) chroma = Y4M_CHROMA_420PALDV;
  else if (!strcmp(tag, "420JPEG"))  chroma = Y4M_CHROMA_420JPEG;
  else if (!strcmp(tag, "444"))      chroma = Y4M_CHROMA_444;
  else chroma = Y4M_UNKNOWN;
  /* Remove the 'X' tag so that no one has to worry about it any more. */
  y4m_xtag_remove(xtags, n);
  /* Hmm... what if there are more XYSCSS tags?  Broken is as broken does;
     thank goodness this is temporary code. */
  return chroma;
}




int y4m_parse_stream_tags(char *s, y4m_stream_info_t *i)
{
  char *token, *value;
  char tag;
  int err;

  /* parse fields */
  for (token = strtok(s, Y4M_DELIM); 
       token != NULL; 
       token = strtok(NULL, Y4M_DELIM)) {
    if (token[0] == '\0') continue;   /* skip empty strings */
    tag = token[0];
    value = token + 1;
    switch (tag) {
    case 'W':  /* width */
      i->width = atoi(value);
      if (i->width <= 0) return Y4M_ERR_RANGE;
      break;
    case 'H':  /* height */
      i->height = atoi(value); 
      if (i->height <= 0) return Y4M_ERR_RANGE;
      break;
    case 'F':  /* frame rate (fps) */
      if ((err = y4m_parse_ratio(&(i->framerate), value)) != Y4M_OK)
	return err;
      if (i->framerate.n < 0) return Y4M_ERR_RANGE;
      break;
    case 'I':  /* interlacing */
      switch (value[0]) {
      case 'p':  i->interlace = Y4M_ILACE_NONE; break;
      case 't':  i->interlace = Y4M_ILACE_TOP_FIRST; break;
      case 'b':  i->interlace = Y4M_ILACE_BOTTOM_FIRST; break;
      case 'm':  i->interlace = Y4M_ILACE_MIXED; break;
      case '?':
      default:
	i->interlace = Y4M_UNKNOWN; break;
      }
      break;
    case 'A':  /* sample (pixel) aspect ratio */
      if ((err = y4m_parse_ratio(&(i->sampleaspect), value)) != Y4M_OK)
	return err;
      if (i->sampleaspect.n < 0) return Y4M_ERR_RANGE;
      break;
    case 'C':
      i->chroma = y4m_chroma_parse_keyword(value);
      if (i->chroma == Y4M_UNKNOWN)
	return Y4M_ERR_HEADER;
      break;
    case 'X':  /* 'X' meta-tag */
      if ((err = y4m_xtag_add(&(i->x_tags), token)) != Y4M_OK) return err;
      break;
    default:
      /* possible error on unknown options */
      if (_y4mparam_allow_unknown_tags) {
	/* unknown tags ok:  store in xtag list and warn... */
	if ((err = y4m_xtag_add(&(i->x_tags), token)) != Y4M_OK) return err;
	mjpeg_warn("Unknown stream tag encountered:  '%s'", token);
      } else {
	/* unknown tags are *not* ok */
	return Y4M_ERR_BADTAG;
      }
      break;
    }
  }

  /* If feature_level > 0, then handle and/or remove any old-style XYSCSS
     chroma tags.  The new-style 'C' tag takes precedence, however. */
  if (_y4mparam_feature_level > 0) {
    int xt_chroma = handle_old_chroma_xtag(i);

    if (i->chroma == Y4M_UNKNOWN)
      i->chroma = xt_chroma;
    else if ((xt_chroma != Y4M_UNKNOWN) &&
             (xt_chroma != i->chroma))
      mjpeg_warn("Old chroma X-tag (ignored) does not match new chroma tag.");
  }

  /* Without 'C' tag or any other chroma spec, default to 420jpeg */
  if (i->chroma == Y4M_UNKNOWN) 
    i->chroma = Y4M_CHROMA_420JPEG;

  /* Error checking... */
  /*      - Width and Height are required. */
  if ((i->width == Y4M_UNKNOWN) || (i->height == Y4M_UNKNOWN))
    return Y4M_ERR_HEADER;
  /*      - Non-420 chroma and mixed interlace require level >= 1 */
  if (_y4mparam_feature_level < 1) {
    if ((i->chroma != Y4M_CHROMA_420JPEG) &&
	(i->chroma != Y4M_CHROMA_420MPEG2) &&
	(i->chroma != Y4M_CHROMA_420PALDV))
      return Y4M_ERR_FEATURE;
    if (i->interlace == Y4M_ILACE_MIXED)
      return Y4M_ERR_FEATURE;
  }

  /* ta da!  done. */
  return Y4M_OK;
}



static int y4m_parse_frame_tags(char *s, const y4m_stream_info_t *si,
				y4m_frame_info_t *fi)
{
  char *token, *value;
  char tag;
  int err;

  /* parse fields */
  for (token = strtok(s, Y4M_DELIM); 
       token != NULL; 
       token = strtok(NULL, Y4M_DELIM)) {
    if (token[0] == '\0') continue;   /* skip empty strings */
    tag = token[0];
    value = token + 1;
    switch (tag) {
    case 'I':
      /* frame 'I' tag requires feature level >= 1 */
      if (_y4mparam_feature_level < 1) return Y4M_ERR_FEATURE;
      if (si->interlace != Y4M_ILACE_MIXED) return Y4M_ERR_BADTAG;
      switch (value[0]) {
      case 't':  fi->presentation = Y4M_PRESENT_TOP_FIRST;        break;
      case 'T':  fi->presentation = Y4M_PRESENT_TOP_FIRST_RPT;    break;
      case 'b':  fi->presentation = Y4M_PRESENT_BOTTOM_FIRST;     break;
      case 'B':  fi->presentation = Y4M_PRESENT_BOTTOM_FIRST_RPT; break;
      case '1':  fi->presentation = Y4M_PRESENT_PROG_SINGLE;      break;
      case '2':  fi->presentation = Y4M_PRESENT_PROG_DOUBLE;      break;
      case '3':  fi->presentation = Y4M_PRESENT_PROG_TRIPLE;      break;
      default: 
	return Y4M_ERR_BADTAG;
      }
      switch (value[1]) {
      case 'p':  fi->temporal = Y4M_SAMPLING_PROGRESSIVE; break;
      case 'i':  fi->temporal = Y4M_SAMPLING_INTERLACED;  break;
      default: 
	return Y4M_ERR_BADTAG;
      }
      switch (value[2]) {
      case 'p':  fi->spatial = Y4M_SAMPLING_PROGRESSIVE; break;
      case 'i':  fi->spatial = Y4M_SAMPLING_INTERLACED;  break;
      case '?':  fi->spatial = Y4M_UNKNOWN;              break;
      default: 
	return Y4M_ERR_BADTAG;
      }
      break;
    case 'X':  /* 'X' meta-tag */
      if ((err = y4m_xtag_add(&(fi->x_tags), token)) != Y4M_OK) return err;
      break;
    default:
      /* possible error on unknown options */
      if (_y4mparam_allow_unknown_tags) {
	/* unknown tags ok:  store in xtag list and warn... */
	if ((err = y4m_xtag_add(&(fi->x_tags), token)) != Y4M_OK) return err;
	mjpeg_warn("Unknown frame tag encountered:  '%s'", token);
      } else {
	/* unknown tags are *not* ok */
	return Y4M_ERR_BADTAG;
      }
      break;
    }
  }
  /* error-checking and/or non-mixed defaults */
  switch (si->interlace) {
  case Y4M_ILACE_MIXED:
    /* T and P are required if stream "Im" */
    if ((fi->presentation == Y4M_UNKNOWN) || (fi->temporal == Y4M_UNKNOWN))
      return Y4M_ERR_HEADER;
    /* and S is required if stream is also 4:2:0 */
    if ( ((si->chroma == Y4M_CHROMA_420JPEG) ||
          (si->chroma == Y4M_CHROMA_420MPEG2) ||
          (si->chroma == Y4M_CHROMA_420PALDV)) &&
         (fi->spatial == Y4M_UNKNOWN) )
      return Y4M_ERR_HEADER;
    break;
  case Y4M_ILACE_NONE:
    /* stream "Ip" --> equivalent to frame "I1pp" */
    fi->spatial = Y4M_SAMPLING_PROGRESSIVE;
    fi->temporal = Y4M_SAMPLING_PROGRESSIVE;
    fi->presentation = Y4M_PRESENT_PROG_SINGLE;
    break;
  case Y4M_ILACE_TOP_FIRST:
    /* stream "It" --> equivalent to frame "Itii" */
    fi->spatial = Y4M_SAMPLING_INTERLACED;
    fi->temporal = Y4M_SAMPLING_INTERLACED;
    fi->presentation = Y4M_PRESENT_TOP_FIRST;
    break;
  case Y4M_ILACE_BOTTOM_FIRST:
    /* stream "Ib" --> equivalent to frame "Ibii" */
    fi->spatial = Y4M_SAMPLING_INTERLACED;
    fi->temporal = Y4M_SAMPLING_INTERLACED;
    fi->presentation = Y4M_PRESENT_BOTTOM_FIRST;
    break;
  default:
    /* stream unknown:  then, whatever */
    break;
  }
  /* ta da!  done. */
  return Y4M_OK;
}





/*************************************************************************
 *
 * Read/Write stream header
 *
 *************************************************************************/


int y4m_read_stream_header(int fd, y4m_stream_info_t *i)
{
   char line[Y4M_LINE_MAX];
   char *p;
   int n;
   int err;

  /* start with a clean slate */
  y4m_clear_stream_info(i);
   /* read the header line */
   for (n = 0, p = line; n < Y4M_LINE_MAX; n++, p++) {
     if (read(fd, p, 1) < 1) 
       return Y4M_ERR_SYSTEM;
     if (*p == '\n') {
       *p = '\0';           /* Replace linefeed by end of string */
       break;
     }
   }
   if (n >= Y4M_LINE_MAX)
      return Y4M_ERR_HEADER;
   /* look for keyword in header */
   if (strncmp(line, Y4M_MAGIC, strlen(Y4M_MAGIC)))
    return Y4M_ERR_MAGIC;
   if ((err = y4m_parse_stream_tags(line + strlen(Y4M_MAGIC), i)) != Y4M_OK)
     return err;

   return Y4M_OK;
}



int y4m_write_stream_header(int fd, const y4m_stream_info_t *i)
{
  char s[Y4M_LINE_MAX+1];
  int n;
  int err;
  y4m_ratio_t rate = i->framerate;
  y4m_ratio_t aspect = i->sampleaspect;
  const char *chroma_keyword = y4m_chroma_keyword(i->chroma);

  if ((i->chroma == Y4M_UNKNOWN) || (chroma_keyword == NULL))
    return Y4M_ERR_HEADER;
  if (_y4mparam_feature_level < 1) {
    if ((i->chroma != Y4M_CHROMA_420JPEG) &&
	(i->chroma != Y4M_CHROMA_420MPEG2) &&
	(i->chroma != Y4M_CHROMA_420PALDV))
      return Y4M_ERR_FEATURE;
    if (i->interlace == Y4M_ILACE_MIXED)
      return Y4M_ERR_FEATURE;
  }
  y4m_ratio_reduce(&rate);
  y4m_ratio_reduce(&aspect);
  n = snprintf(s, sizeof(s), "%s W%d H%d F%d:%d I%s A%d:%d C%s",
	       Y4M_MAGIC,
	       i->width,
	       i->height,
	       rate.n, rate.d,
	       (i->interlace == Y4M_ILACE_NONE) ? "p" :
	       (i->interlace == Y4M_ILACE_TOP_FIRST) ? "t" :
	       (i->interlace == Y4M_ILACE_BOTTOM_FIRST) ? "b" :
	       (i->interlace == Y4M_ILACE_MIXED) ? "m" : "?",
	       aspect.n, aspect.d,
	       chroma_keyword
	       );
  if ((n < 0) || (n > Y4M_LINE_MAX)) return Y4M_ERR_HEADER;
  if ((err = y4m_snprint_xtags(s + n, sizeof(s) - n - 1, &(i->x_tags))) 
      != Y4M_OK) 
    return err;
  /* non-zero on error */
  return (y4m_write(fd, s, strlen(s)) ? Y4M_ERR_SYSTEM : Y4M_OK);
}





/*************************************************************************
 *
 * Read/Write frame header
 *
 *************************************************************************/

int y4m_read_frame_header(int fd,
			  const y4m_stream_info_t *si,
			  y4m_frame_info_t *fi)
{
  char line[Y4M_LINE_MAX];
  char *p;
  int n;
  ssize_t remain;
  
  /* start with a clean slate */
  y4m_clear_frame_info(fi);
  /* This is more clever than read_stream_header...
     Try to read "FRAME\n" all at once, and don't try to parse
     if nothing else is there...
  */
  remain = y4m_read(fd, line, sizeof(Y4M_FRAME_MAGIC)-1+1); /* -'\0', +'\n' */
  if (remain < 0) return Y4M_ERR_SYSTEM;
  if (remain > 0) {
    /* A clean EOF should end exactly at a frame-boundary */
    if (remain == sizeof(Y4M_FRAME_MAGIC))
      return Y4M_ERR_EOF;
    else
      return Y4M_ERR_BADEOF;
  }
  if (strncmp(line, Y4M_FRAME_MAGIC, sizeof(Y4M_FRAME_MAGIC)-1))
    return Y4M_ERR_MAGIC;
  if (line[sizeof(Y4M_FRAME_MAGIC)-1] == '\n')
    return Y4M_OK; /* done -- no tags:  that was the end-of-line. */

  if (line[sizeof(Y4M_FRAME_MAGIC)-1] != Y4M_DELIM[0]) {
    return Y4M_ERR_MAGIC; /* wasn't a space -- what was it? */
  }

  /* proceed to get the tags... (overwrite the magic) */
  for (n = 0, p = line; n < Y4M_LINE_MAX; n++, p++) {
    if (y4m_read(fd, p, 1))
      return Y4M_ERR_SYSTEM;
    if (*p == '\n') {
      *p = '\0';           /* Replace linefeed by end of string */
      break;
    }
  }
  if (n >= Y4M_LINE_MAX) return Y4M_ERR_HEADER;