y4minput.c

/*
 *  Copyright (c) 2010 The VP8 project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 *
 *  Based on code from the OggTheora software codec source code,
 *  Copyright (C) 2002-2010 The Xiph.Org Foundation and contributors.
 */
#include <stdlib.h>
#include <string.h>
#include "y4minput.h"

static int y4m_parse_tags(y4m_input *_y4m,char *_tags){
  int   got_w;
  int   got_h;
  int   got_fps;
  int   got_interlace;
  int   got_par;
  int   got_chroma;
  char *p;
  char *q;
  got_w=got_h=got_fps=got_interlace=got_par=got_chroma=0;
  for(p=_tags;;p=q){
    /*Skip any leading spaces.*/
    while(*p==' ')p++;
    /*If that's all we have, stop.*/
    if(p[0]=='\0')break;
    /*Find the end of this tag.*/
    for(q=p+1;*q!='\0'&&*q!=' ';q++);
    /*Process the tag.*/
    switch(p[0]){
      case 'W':{
        if(sscanf(p+1,"%d",&_y4m->pic_w)!=1)return -1;
        got_w=1;
      }break;
      case 'H':{
        if(sscanf(p+1,"%d",&_y4m->pic_h)!=1)return -1;
        got_h=1;
      }break;
      case 'F':{
        if(sscanf(p+1,"%d:%d",&_y4m->fps_n,&_y4m->fps_d)!=2){
          return -1;
        }
        got_fps=1;
      }break;
      case 'I':{
        _y4m->interlace=p[1];
        got_interlace=1;
      }break;
      case 'A':{
        if(sscanf(p+1,"%d:%d",&_y4m->par_n,&_y4m->par_d)!=2){
          return -1;
        }
        got_par=1;
      }break;
      case 'C':{
        if(q-p>16)return -1;
        memcpy(_y4m->chroma_type,p+1,q-p-1);
        _y4m->chroma_type[q-p-1]='\0';
        got_chroma=1;
      }break;
      /*Ignore unknown tags.*/
    }
  }
  if(!got_w||!got_h||!got_fps)return -1;
  if(!got_interlace)_y4m->interlace='?';