dvd_reader.c

有关mpeg2的deocde代码

        break;
    default:
        fprintf( stderr, "libdvdread: Invalid domain for file open.\n" );
        return NULL;
    }
    
    if( dvd->isImageFile ) {
        return DVDOpenFileUDF( dvd, filename );
    } else {
        return DVDOpenFilePath( dvd, filename );
    }
}

void DVDCloseFile( dvd_file_t *dvd_file )
{
    int i;

    if( dvd_file ) {
        if( dvd_file->dvd->isImageFile ) {
	    ;
	} else {
            for( i = 0; i < 9; ++i ) {
                if( dvd_file->title_devs[ i ] ) {
                    dvdinput_close( dvd_file->title_devs[i] );
                }
            }
        }

        free( dvd_file );
        dvd_file = 0;
    }
}

/* Internal, but used from dvd_udf.c */
int UDFReadBlocksRaw( dvd_reader_t *device, uint32_t lb_number,
			 size_t block_count, unsigned char *data, 
			 int encrypted )
{
   int ret;

   if( !device->dev ) {
     	fprintf( stderr, "libdvdread: Fatal error in block read.\n" );
	return 0;
   }

   ret = dvdinput_seek( device->dev, (int) lb_number );
   if( ret != (int) lb_number ) {
     	fprintf( stderr, "libdvdread: Can't seek to block %u\n", lb_number );
	return 0;
   }

   return dvdinput_read( device->dev, (char *) data, 
			 (int) block_count, encrypted );
}

/* This is using a single input and starting from 'dvd_file->lb_start' offset.
 *
 * Reads 'block_count' blocks from 'dvd_file' at block offset 'offset'
 * into the buffer located at 'data' and if 'encrypted' is set
 * descramble the data if it's encrypted.  Returning either an
 * negative error or the number of blocks read. */
static int DVDReadBlocksUDF( dvd_file_t *dvd_file, uint32_t offset,
			     size_t block_count, unsigned char *data,
			     int encrypted )
{
    return UDFReadBlocksRaw( dvd_file->dvd, dvd_file->lb_start + offset,
			     block_count, data, encrypted );
}

/* This is using possibly several inputs and starting from an offset of '0'.
 *
 * Reads 'block_count' blocks from 'dvd_file' at block offset 'offset'
 * into the buffer located at 'data' and if 'encrypted' is set
 * descramble the data if it's encrypted.  Returning either an
 * negative error or the number of blocks read. */
static int DVDReadBlocksPath( dvd_file_t *dvd_file, unsigned int offset,
			      size_t block_count, unsigned char *data,
			      int encrypted )
{
    int i;
    int ret, ret2, off;

    ret = 0;
    ret2 = 0;
    for( i = 0; i < 9; ++i ) {
      if( !dvd_file->title_sizes[ i ] ) return 0; /* Past end of file */

        if( offset < dvd_file->title_sizes[ i ] ) {
            if( ( offset + block_count ) <= dvd_file->title_sizes[ i ] ) {
		off = dvdinput_seek( dvd_file->title_devs[ i ], (int)offset );
                if( off < 0 || off != (int)offset ) {
		    fprintf( stderr, "libdvdread: Can't seek to block %d\n", 
			     offset );
		    return off < 0 ? off : 0;
		}
                ret = dvdinput_read( dvd_file->title_devs[ i ], data,
				     (int)block_count, encrypted );
                break;
            } else {
                size_t part1_size = dvd_file->title_sizes[ i ] - offset;
		/* FIXME: Really needs to be a while loop.
                 * (This is only true if you try and read >1GB at a time) */
		
                /* Read part 1 */
                off = dvdinput_seek( dvd_file->title_devs[ i ], (int)offset );
                if( off < 0 || off != (int)offset ) {
		    fprintf( stderr, "libdvdread: Can't seek to block %d\n", 
			     offset );
		    return off < 0 ? off : 0;
		}
                ret = dvdinput_read( dvd_file->title_devs[ i ], data,
				     (int)part1_size, encrypted );
		if( ret < 0 ) return ret;
		/* FIXME: This is wrong if i is the last file in the set. 
                 * also error from this read will not show in ret. */
		
		/* Does the next part exist? If not then return now. */
		if( !dvd_file->title_devs[ i + 1 ] ) return ret;

                /* Read part 2 */
                off = dvdinput_seek( dvd_file->title_devs[ i + 1 ], 0 );
                if( off < 0 || off != 0 ) {
		    fprintf( stderr, "libdvdread: Can't seek to block %d\n", 
			     0 );
		    return off < 0 ? off : 0;
		}
                ret2 = dvdinput_read( dvd_file->title_devs[ i + 1 ], 
				      data + ( part1_size
					       * (int64_t)DVD_VIDEO_LB_LEN ),
				      (int)(block_count - part1_size),
				      encrypted );
                if( ret2 < 0 ) return ret2;
		break;
            }
        } else {
            offset -= dvd_file->title_sizes[ i ];
        }
    }

    return ret + ret2;
}

/* This is broken reading more than 2Gb at a time is ssize_t is 32-bit. */
ssize_t DVDReadBlocks( dvd_file_t *dvd_file, int offset, 
		       size_t block_count, unsigned char *data )
{
    int ret;
    
    /* Check arguments. */
    if( dvd_file == NULL || offset < 0 || data == NULL )
      return -1;
    
    /* Hack, and it will still fail for multiple opens in a threaded app ! */
    if( dvd_file->dvd->css_title != dvd_file->css_title ) {
      dvd_file->dvd->css_title = dvd_file->css_title;
      if( dvd_file->dvd->isImageFile ) {
	dvdinput_title( dvd_file->dvd->dev, (int)dvd_file->lb_start );
      } 
      /* Here each vobu has it's own dvdcss handle, so no need to update 
      else {
	dvdinput_title( dvd_file->title_devs[ 0 ], (int)dvd_file->lb_start );
      }*/
    }
    
    if( dvd_file->dvd->isImageFile ) {
	ret = DVDReadBlocksUDF( dvd_file, (uint32_t)offset, 
				block_count, data, DVDINPUT_READ_DECRYPT );
    } else {
	ret = DVDReadBlocksPath( dvd_file, (unsigned int)offset, 
				 block_count, data, DVDINPUT_READ_DECRYPT );
    }
    
    return (ssize_t)ret;
}

int32_t DVDFileSeek( dvd_file_t *dvd_file, int32_t offset )
{
    /* Check arguments. */
    if( dvd_file == NULL || offset < 0 )
       return -1;
    
    if( offset > dvd_file->filesize * DVD_VIDEO_LB_LEN ) {
       return -1;
    }
    dvd_file->seek_pos = (uint32_t) offset;
    return offset;
}

ssize_t DVDReadBytes( dvd_file_t *dvd_file, void *data, size_t byte_size )
{
    unsigned char *secbuf;
    unsigned int numsec, seek_sector, seek_byte;
    int ret;
    
    /* Check arguments. */
    if( dvd_file == NULL || data == NULL )
      return -1;

    seek_sector = dvd_file->seek_pos / DVD_VIDEO_LB_LEN;
    seek_byte   = dvd_file->seek_pos % DVD_VIDEO_LB_LEN;

    numsec = ( ( seek_byte + byte_size ) / DVD_VIDEO_LB_LEN ) +
      ( ( ( seek_byte + byte_size ) % DVD_VIDEO_LB_LEN ) ? 1 : 0 );
    
    secbuf = (unsigned char *) malloc( numsec * DVD_VIDEO_LB_LEN );
    if( !secbuf ) {
	fprintf( stderr, "libdvdread: Can't allocate memory " 
		 "for file read!\n" );
        return 0;
    }
    
    if( dvd_file->dvd->isImageFile ) {
	ret = DVDReadBlocksUDF( dvd_file, (uint32_t) seek_sector, 
				(size_t) numsec, secbuf, DVDINPUT_NOFLAGS );
    } else {
	ret = DVDReadBlocksPath( dvd_file, seek_sector, 
				 (size_t) numsec, secbuf, DVDINPUT_NOFLAGS );
    }

    if( ret != (int) numsec ) {
        free( secbuf );
        return ret < 0 ? ret : 0;
    }

    memcpy( data, &(secbuf[ seek_byte ]), byte_size );
    free( secbuf );

    dvd_file->seek_pos += byte_size;
    return byte_size;
}

ssize_t DVDFileSize( dvd_file_t *dvd_file )
{
    /* Check arguments. */
    if( dvd_file == NULL )
      return -1;
    
    return dvd_file->filesize;
}

int DVDDiscID( dvd_reader_t *dvd, unsigned char *discid )
{
    struct md5_ctx ctx;
    int title;

    /* Check arguments. */
    if( dvd == NULL || discid == NULL )
      return 0;
    
    /* Go through the first 10 IFO:s, in order, 
     * and md5sum them, i.e  VIDEO_TS.IFO and VTS_0?_0.IFO */
    md5_init_ctx( &ctx );
    for( title = 0; title < 10; title++ ) {
	dvd_file_t *dvd_file = DVDOpenFile( dvd, title, DVD_READ_INFO_FILE );
	if( dvd_file != NULL ) {
	    ssize_t bytes_read;
	    size_t file_size = dvd_file->filesize * DVD_VIDEO_LB_LEN;
	    char *buffer = malloc( file_size );
	    
	    if( buffer == NULL ) {
		fprintf( stderr, "libdvdread: DVDDiscId, failed to "
			 "allocate memory for file read!\n" );
		return -1;
	    }
	    bytes_read = DVDReadBytes( dvd_file, buffer, file_size );
	    if( bytes_read != file_size ) {
		fprintf( stderr, "libdvdread: DVDDiscId read returned %d bytes"
			 ", wanted %d\n", bytes_read, file_size );
		DVDCloseFile( dvd_file );
		return -1;
	    }
	    
	    md5_process_bytes( buffer, file_size,  &ctx );
	    
	    DVDCloseFile( dvd_file );
	    free( buffer );
	}
    }
    md5_finish_ctx( &ctx, discid );
    
    return 0;
}


int DVDISOVolumeInfo( dvd_reader_t *dvd,
		      char *volid, unsigned int volid_size,
		      unsigned char *volsetid, unsigned int volsetid_size )
{
  unsigned char *buffer;
  int ret;

  /* Check arguments. */
  if( dvd == NULL )
    return 0;
  
  if( dvd->dev == NULL ) {
    /* No block access, so no ISO... */
    return -1;
  }
  
  buffer = malloc( DVD_VIDEO_LB_LEN );
  if( buffer == NULL ) {
    fprintf( stderr, "libdvdread: DVDISOVolumeInfo, failed to "
	     "allocate memory for file read!\n" );
    return -1;
  }

  ret = UDFReadBlocksRaw( dvd, 16, 1, buffer, 0 );
  if( ret != 1 ) {
    fprintf( stderr, "libdvdread: DVDISOVolumeInfo, failed to "
	     "read ISO9660 Primary Volume Descriptor!\n" );
    return -1;
  }
  
  if( (volid != NULL) && (volid_size > 0) ) {
    unsigned int n;
    for(n = 0; n < 32; n++) {
      if(buffer[40+n] == 0x20) {
	break;
      }
    }
    
    if(volid_size > n+1) {
      volid_size = n+1;
    }

    memcpy(volid, &buffer[40], volid_size-1);
    volid[volid_size-1] = '\0';
  }
  
  if( (volsetid != NULL) && (volsetid_size > 0) ) {
    if(volsetid_size > 128) {
      volsetid_size = 128;
    }
    memcpy(volsetid, &buffer[190], volsetid_size);
  }
  return 0;
}


int DVDUDFVolumeInfo( dvd_reader_t *dvd,
		      char *volid, unsigned int volid_size,
		      unsigned char *volsetid, unsigned int volsetid_size )
{
  int ret;
  /* Check arguments. */
  if( dvd == NULL )
    return -1;
  
  if( dvd->dev == NULL ) {
    /* No block access, so no UDF VolumeSet Identifier */
    return -1;
  }
  
  if( (volid != NULL) && (volid_size > 0) ) {
    ret = UDFGetVolumeIdentifier(dvd, volid, volid_size);
    if(!ret) {
      return -1;
    }
  }
  if( (volsetid != NULL) && (volsetid_size > 0) ) {
    ret =  UDFGetVolumeSetIdentifier(dvd, volsetid, volsetid_size);
    if(!ret) {
      return -1;
    }
  }
    
  return 0;  
}