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comparison decoders/voc.c @ 474:c66080364dff

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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.
author Ryan C. Gordon <icculus@icculus.org>
date Sat, 08 May 2004 08:19:50 +0000
parents cd46c97e58bc
children 3e705c9180e5
comparison
equal deleted inserted replaced
473:1edb89260487 474:c66080364dff
194 Uint32 sblen; 194 Uint32 sblen;
195 Uint16 new_rate_short; 195 Uint16 new_rate_short;
196 Uint32 new_rate_long; 196 Uint32 new_rate_long;
197 Uint8 trash[6]; 197 Uint8 trash[6];
198 Uint16 period; 198 Uint16 period;
199 Uint32 bytes_per_second;
199 int i; 200 int i;
200 201
201 v->silent = 0; 202 v->silent = 0;
202 while (v->rest == 0) 203 while (v->rest == 0)
203 { 204 {
239 BAIL_IF_MACRO(uc != 0, "VOC: only supports 8-bit data", 0); 240 BAIL_IF_MACRO(uc != 0, "VOC: only supports 8-bit data", 0);
240 241
241 v->extended = 0; 242 v->extended = 0;
242 v->rest = sblen - 2; 243 v->rest = sblen - 2;
243 v->size = ST_SIZE_BYTE; 244 v->size = ST_SIZE_BYTE;
245
246 bytes_per_second = sample->actual.rate
247 * sample->actual.channels;
248 sample->total_time += ( v->rest ) / bytes_per_second * 1000;
249 sample->total_time += (v->rest % bytes_per_second) * 1000
250 / bytes_per_second;
244 return 1; 251 return 1;
245 252
246 case VOC_DATA_16: 253 case VOC_DATA_16:
247 if (!voc_readbytes(src, v, &new_rate_long, sizeof (Uint32))) 254 if (!voc_readbytes(src, v, &new_rate_long, sizeof (Uint32)))
248 return 0; 255 return 0;
270 if (!voc_readbytes(src, v, &v->channels, sizeof (Uint8))) 277 if (!voc_readbytes(src, v, &v->channels, sizeof (Uint8)))
271 return 0; 278 return 0;
272 279
273 if (!voc_readbytes(src, v, trash, sizeof (Uint8) * 6)) 280 if (!voc_readbytes(src, v, trash, sizeof (Uint8) * 6))
274 return 0; 281 return 0;
275
276 v->rest = sblen - 12; 282 v->rest = sblen - 12;
283
284 bytes_per_second = ((v->size == ST_SIZE_WORD) ? (2) : (1)) *
285 sample->actual.rate * v->channels;
286 sample->total_time += v->rest / bytes_per_second * 1000;
287 sample->total_time += ( v->rest % bytes_per_second ) * 1000
288 / bytes_per_second;
277 return 1; 289 return 1;
278 290
279 case VOC_CONT: 291 case VOC_CONT:
280 v->rest = sblen; 292 v->rest = sblen;
281 return 1; 293 return 1;
300 period = (period * (256 - uc))/(256 - v->rate); 312 period = (period * (256 - uc))/(256 - v->rate);
301 else 313 else
302 v->rate = uc; 314 v->rate = uc;
303 v->rest = period; 315 v->rest = period;
304 v->silent = 1; 316 v->silent = 1;
317
318 sample->total_time += (period) / (v->rate) * 1000;
319 sample->total_time += (period % v->rate) * 1000 / v->rate;
305 return 1; 320 return 1;
306 321
307 case VOC_LOOP: 322 case VOC_LOOP:
308 case VOC_LOOPEND: 323 case VOC_LOOPEND:
309 for(i = 0; i < sblen; i++) /* skip repeat loops. */ 324 for(i = 0; i < sblen; i++) /* skip repeat loops. */