dxhead.cpp
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上传日期:2013-07-19
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- /* ***** BEGIN LICENSE BLOCK *****
- * Version: RCSL 1.0/RPSL 1.0
- *
- * Portions Copyright (c) 1995-2002 RealNetworks, Inc. All Rights Reserved.
- *
- * The contents of this file, and the files included with this file, are
- * subject to the current version of the RealNetworks Public Source License
- * Version 1.0 (the "RPSL") available at
- * http://www.helixcommunity.org/content/rpsl unless you have licensed
- * the file under the RealNetworks Community Source License Version 1.0
- * (the "RCSL") available at http://www.helixcommunity.org/content/rcsl,
- * in which case the RCSL will apply. You may also obtain the license terms
- * directly from RealNetworks. You may not use this file except in
- * compliance with the RPSL or, if you have a valid RCSL with RealNetworks
- * applicable to this file, the RCSL. Please see the applicable RPSL or
- * RCSL for the rights, obligations and limitations governing use of the
- * contents of the file.
- *
- * This file is part of the Helix DNA Technology. RealNetworks is the
- * developer of the Original Code and owns the copyrights in the portions
- * it created.
- *
- * This file, and the files included with this file, is distributed and made
- * available on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
- * EXPRESS OR IMPLIED, AND REALNETWORKS HEREBY DISCLAIMS ALL SUCH WARRANTIES,
- * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS
- * FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
- *
- * Technology Compatibility Kit Test Suite(s) Location:
- * http://www.helixcommunity.org/content/tck
- *
- * Contributor(s):
- *
- * ***** END LICENSE BLOCK ***** */
- #include "hlxclib/stdlib.h"
- #include "hlxclib/stdio.h"
- #include "hlxclib/float.h"
- #include "hlxclib/math.h"
- #include "dxhead.h"
- // 4 Xing
- // 4 flags
- // 4 frames
- // 4 bytes
- // 100 toc
- /*-------------------------------------------------------------*/
- static int ExtractI4(unsigned char *buf)
- {
- int x;
- // big endian extract
- x = buf[0];
- x <<= 8;
- x |= buf[1];
- x <<= 8;
- x |= buf[2];
- x <<= 8;
- x |= buf[3];
- return x;
- }
- /*-------------------------------------------------------------*/
- int GetXingHeader(XHEADDATA *X, unsigned char *buf)
- {
- int i, head_flags;
- int h_id, h_mode, h_sr_index;
- static const int sr_table[4] = { 44100, 48000, 32000, 99999 };
- // get Xing header data
- X->flags = 0; // clear to null incase fail
- // get selected MPEG header data
- h_id = (buf[1] >> 3) & 1;
- h_sr_index = (buf[2] >> 2) & 3;
- h_mode = (buf[3] >> 6) & 3;
- // determine offset of header
- if( h_id ) { // mpeg1
- if( h_mode != 3 ) buf+=(32+4);
- else buf+=(17+4);
- }
- else { // mpeg2
- if( h_mode != 3 ) buf+=(17+4);
- else buf+=(9+4);
- }
- if( buf[0] != 'X' ) return 0; // fail
- if( buf[1] != 'i' ) return 0; // header not found
- if( buf[2] != 'n' ) return 0;
- if( buf[3] != 'g' ) return 0;
- buf+=4;
- X->h_id = h_id;
- X->samprate = sr_table[h_sr_index];
- if( h_id == 0 ) X->samprate >>= 1;
- head_flags = X->flags = ExtractI4(buf); buf+=4; // get flags
- if( head_flags & FRAMES_FLAG ) {X->frames = ExtractI4(buf); buf+=4;}
- if( head_flags & BYTES_FLAG ) {X->bytes = ExtractI4(buf); buf+=4;}
- if( head_flags & TOC_FLAG ) {
- if( X->toc != NULL ) {
- for(i=0;i<100;i++) X->toc[i] = buf[i];
- }
- buf+=100;
- }
- X->vbr_scale = -1;
- if( head_flags & VBR_SCALE_FLAG ) {X->vbr_scale = ExtractI4(buf); buf+=4;}
- //if( X->toc != NULL ) {
- //for(i=0;i<100;i++) {
- // if( (i%10) == 0 ) printf("n");
- // printf(" %3d", (int)(X->toc[i]));
- //}
- //}
- return 1; // success
- }
- /*-------------------------------------------------------------*/
- int SeekPoint(unsigned char TOC[100], int file_bytes, float percent) /* Flawfinder: ignore */
- {
- // interpolate in TOC to get file seek point in bytes
- int a, seekpoint;
- float fa, fb, fx;
- if( percent < 0.0f ) percent = 0.0f;
- if( percent > 100.0f ) percent = 100.0f;
- a = (int)percent;
- if( a > 99 ) a = 99;
- fa = TOC[a];
- if( a < 99 ) {
- fb = TOC[a+1];
- }
- else {
- fb = 256.0f;
- }
- fx = fa + (fb-fa)*(percent-a);
- seekpoint = (int)((1.0f/256.0f)*fx*file_bytes);
- return seekpoint;
- }
- /*-------------------------------------------------------------*/