Most decoders now report total sample play time, now. Technically, this breaks binary compatibility with the 1.0 branch, since it extends the Sound_Sample struct, but most (all?) programs are just passing pointers allocated by SDL_sound around, and might be okay. Source-level compatibility is not broken...yet! :) --ryan. -------- Original Message -------- Subject: SDL_sound patch: Finding total length of time of sound file. Date: Sun, 26 Jan 2003 09:31:17 -0800 (PST) Hi Ryan, I am working with Eric Wing and helping him modify SDL_sound. AS part of our efforts in improving and enhancing SDL_sound, we like to submit this patch. We modified the codecs to find the total time of a sound file. Below is the explanation of the patch. The patch is appended as an attachment to this email. * MOTIVATION: We needed the ability to get the total play time of a sample (And we noticed that we're not the only ones). Since SDL_sound blocks direct access to the specific decoders, there is no way for a user to know this information short of decoding the whole thing. Because of this, we believe this will be a useful addition, even though the accuracy may not be perfect (subject to each decoder) or the information may not always be available. * CONTRIBUTORS: Wesley Leong (modified the majority of the codecs and verified the results) Eric Wing (showed everyone how to do modify codec, modified mikmod) Wang Lam (modified a handful of codecs, researched into specs and int overflow) Ahilan Anantha (modified a few codecs and helped with integer math) * GENERAL ISSUES: We chose the value to be milliseconds as an Sint32. Milliseconds because that's what Sound_Seek takes as a parameter and -1 to allow for instances/codecs where the value could not be determined. We are not sure if this is the final convention you want, so we are willing to work with you on this. We also expect the total_time field to be set on open and never again modified by SDL_sound. Users may access it directly much like the sample buffer and buffer_size. We thought about recomputing the time on DecodeAll, but since users may seek or decode small chunks first, not all the data may be there. So this is better done by the user. This may be good information to document. Currently, all the main codecs are implemented except for QuickTime.

/* 

    TiMidity -- Experimental MIDI to WAVE converter
    Copyright (C) 1995 Tuukka Toivonen <toivonen@clinet.fi>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

    output.h

*/

/* Data format encoding bits */

#define PE_MONO 	0x01  /* versus stereo */
#define PE_SIGNED	0x02  /* versus unsigned */
#define PE_16BIT 	0x04  /* versus 8-bit */

/* Conversion functions -- These overwrite the Sint32 data in *lp with
   data in another format */

/* 8-bit signed and unsigned*/
extern void s32tos8(void *dp, Sint32 *lp, Sint32 c);
extern void s32tou8(void *dp, Sint32 *lp, Sint32 c);

/* 16-bit */
extern void s32tos16(void *dp, Sint32 *lp, Sint32 c);
extern void s32tou16(void *dp, Sint32 *lp, Sint32 c);

/* byte-exchanged 16-bit */
extern void s32tos16x(void *dp, Sint32 *lp, Sint32 c);
extern void s32tou16x(void *dp, Sint32 *lp, Sint32 c);

/* little-endian and big-endian specific */
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
#define s32tou16l s32tou16
#define s32tou16b s32tou16x
#define s32tos16l s32tos16
#define s32tos16b s32tos16x
#else
#define s32tou16l s32tou16x
#define s32tou16b s32tou16
#define s32tos16l s32tos16x
#define s32tos16b s32tos16
#endif