git.sesse.net Git - ffmpeg/blob - libswresample/swresample.c

   1 /*
   2  * Copyright (C) 2011 Michael Niedermayer (michaelni@gmx.at)
   3  *
   4  * This file is part of libswresample
   5  *
   6  * libswresample is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * libswresample is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with libswresample; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 #include "libavutil/opt.h"
  22 #include "swresample_internal.h"
  23 #include "audioconvert.h"
  24 #include "libavutil/avassert.h"
  25 #include "libavutil/audioconvert.h"
  26
  27 #define  C30DB  M_SQRT2
  28 #define  C15DB  1.189207115
  29 #define C__0DB  1.0
  30 #define C_15DB  0.840896415
  31 #define C_30DB  M_SQRT1_2
  32 #define C_45DB  0.594603558
  33 #define C_60DB  0.5
  34
  35
  36 //TODO split options array out?
  37 #define OFFSET(x) offsetof(SwrContext,x)
  38 static const AVOption options[]={
  39 {"ich",  "input channel count", OFFSET( in.ch_count   ), AV_OPT_TYPE_INT, {.dbl=2}, 0, SWR_CH_MAX, 0},
  40 {"och", "output channel count", OFFSET(out.ch_count   ), AV_OPT_TYPE_INT, {.dbl=2}, 0, SWR_CH_MAX, 0},
  41 {"uch",   "used channel count", OFFSET(used_ch_count  ), AV_OPT_TYPE_INT, {.dbl=0}, 0, SWR_CH_MAX, 0},
  42 {"isr",  "input sample rate"  , OFFSET( in_sample_rate), AV_OPT_TYPE_INT, {.dbl=48000}, 1, INT_MAX, 0},
  43 {"osr", "output sample rate"  , OFFSET(out_sample_rate), AV_OPT_TYPE_INT, {.dbl=48000}, 1, INT_MAX, 0},
  44 //{"ip" ,  "input planar"       , OFFSET( in.planar     ), AV_OPT_TYPE_INT, {.dbl=0},    0,       1, 0},
  45 //{"op" , "output planar"       , OFFSET(out.planar     ), AV_OPT_TYPE_INT, {.dbl=0},    0,       1, 0},
  46 {"isf",  "input sample format", OFFSET( in_sample_fmt ), AV_OPT_TYPE_INT, {.dbl=AV_SAMPLE_FMT_S16}, 0, AV_SAMPLE_FMT_NB-1+256, 0},
  47 {"osf", "output sample format", OFFSET(out_sample_fmt ), AV_OPT_TYPE_INT, {.dbl=AV_SAMPLE_FMT_S16}, 0, AV_SAMPLE_FMT_NB-1+256, 0},
  48 {"tsf", "internal sample format", OFFSET(int_sample_fmt ), AV_OPT_TYPE_INT, {.dbl=AV_SAMPLE_FMT_NONE}, -1, AV_SAMPLE_FMT_FLT, 0},
  49 {"icl",  "input channel layout" , OFFSET( in_ch_layout), AV_OPT_TYPE_INT64, {.dbl=0}, 0, INT64_MAX, 0, "channel_layout"},
  50 {"ocl",  "output channel layout", OFFSET(out_ch_layout), AV_OPT_TYPE_INT64, {.dbl=0}, 0, INT64_MAX, 0, "channel_layout"},
  51 {"clev", "center mix level"     , OFFSET(clev)         , AV_OPT_TYPE_FLOAT, {.dbl=C_30DB}, 0, 4, 0},
  52 {"slev", "sourround mix level"  , OFFSET(slev)         , AV_OPT_TYPE_FLOAT, {.dbl=C_30DB}, 0, 4, 0},
  53 {"rmvol", "rematrix volume"     , OFFSET(rematrix_volume), AV_OPT_TYPE_FLOAT, {.dbl=1.0}, -1000, 1000, 0},
  54 {"flags", NULL                  , OFFSET(flags)        , AV_OPT_TYPE_FLAGS, {.dbl=0}, 0,  UINT_MAX, 0, "flags"},
  55 {"res", "force resampling", 0, AV_OPT_TYPE_CONST, {.dbl=SWR_FLAG_RESAMPLE}, INT_MIN, INT_MAX, 0, "flags"},
  56
  57 {0}
  58 };
  59
  60 static const char* context_to_name(void* ptr) {
  61     return "SWR";
  62 }
  63
  64 static const AVClass av_class = {
  65     .class_name                = "SwrContext",
  66     .item_name                 = context_to_name,
  67     .option                    = options,
  68     .version                   = LIBAVUTIL_VERSION_INT,
  69     .log_level_offset_offset   = OFFSET(log_level_offset),
  70     .parent_log_context_offset = OFFSET(log_ctx),
  71 };
  72
  73 unsigned swresample_version(void)
  74 {
  75     av_assert0(LIBSWRESAMPLE_VERSION_MICRO >= 100);
  76     return LIBSWRESAMPLE_VERSION_INT;
  77 }
  78
  79 const char *swresample_configuration(void)
  80 {
  81     return FFMPEG_CONFIGURATION;
  82 }
  83
  84 const char *swresample_license(void)
  85 {
  86 #define LICENSE_PREFIX "libswresample license: "
  87     return LICENSE_PREFIX FFMPEG_LICENSE + sizeof(LICENSE_PREFIX) - 1;
  88 }
  89
  90 int swr_set_channel_mapping(struct SwrContext *s, const int *channel_map){
  91     if(!s || s->in_convert) // s needs to be allocated but not initialized
  92         return AVERROR(EINVAL);
  93     s->channel_map = channel_map;
  94     return 0;
  95 }
  96
  97 struct SwrContext *swr_alloc(void){
  98     SwrContext *s= av_mallocz(sizeof(SwrContext));
  99     if(s){
 100         s->av_class= &av_class;
 101         av_opt_set_defaults(s);
 102     }
 103     return s;
 104 }
 105
 106 struct SwrContext *swr_alloc_set_opts(struct SwrContext *s,
 107                                       int64_t out_ch_layout, enum AVSampleFormat out_sample_fmt, int out_sample_rate,
 108                                       int64_t  in_ch_layout, enum AVSampleFormat  in_sample_fmt, int  in_sample_rate,
 109                                       int log_offset, void *log_ctx){
 110     if(!s) s= swr_alloc();
 111     if(!s) return NULL;
 112
 113     s->log_level_offset= log_offset;
 114     s->log_ctx= log_ctx;
 115
 116     av_opt_set_int(s, "ocl", out_ch_layout,   0);
 117     av_opt_set_int(s, "osf", out_sample_fmt,  0);
 118     av_opt_set_int(s, "osr", out_sample_rate, 0);
 119     av_opt_set_int(s, "icl", in_ch_layout,    0);
 120     av_opt_set_int(s, "isf", in_sample_fmt,   0);
 121     av_opt_set_int(s, "isr", in_sample_rate,  0);
 122     av_opt_set_int(s, "tsf", AV_SAMPLE_FMT_S16, 0);
 123     av_opt_set_int(s, "ich", av_get_channel_layout_nb_channels(s-> in_ch_layout), 0);
 124     av_opt_set_int(s, "och", av_get_channel_layout_nb_channels(s->out_ch_layout), 0);
 125     av_opt_set_int(s, "uch", 0, 0);
 126     return s;
 127 }
 128
 129
 130 static void free_temp(AudioData *a){
 131     av_free(a->data);
 132     memset(a, 0, sizeof(*a));
 133 }
 134
 135 void swr_free(SwrContext **ss){
 136     SwrContext *s= *ss;
 137     if(s){
 138         free_temp(&s->postin);
 139         free_temp(&s->midbuf);
 140         free_temp(&s->preout);
 141         free_temp(&s->in_buffer);
 142         swri_audio_convert_free(&s-> in_convert);
 143         swri_audio_convert_free(&s->out_convert);
 144         swri_audio_convert_free(&s->full_convert);
 145         swri_resample_free(&s->resample);
 146     }
 147
 148     av_freep(ss);
 149 }
 150
 151 int swr_init(struct SwrContext *s){
 152     s->in_buffer_index= 0;
 153     s->in_buffer_count= 0;
 154     s->resample_in_constraint= 0;
 155     free_temp(&s->postin);
 156     free_temp(&s->midbuf);
 157     free_temp(&s->preout);
 158     free_temp(&s->in_buffer);
 159     swri_audio_convert_free(&s-> in_convert);
 160     swri_audio_convert_free(&s->out_convert);
 161     swri_audio_convert_free(&s->full_convert);
 162
 163     s-> in.planar= av_sample_fmt_is_planar(s-> in_sample_fmt);
 164     s->out.planar= av_sample_fmt_is_planar(s->out_sample_fmt);
 165     s-> in_sample_fmt= av_get_alt_sample_fmt(s-> in_sample_fmt, 0);
 166     s->out_sample_fmt= av_get_alt_sample_fmt(s->out_sample_fmt, 0);
 167
 168     if(s-> in_sample_fmt >= AV_SAMPLE_FMT_NB){
 169         av_log(s, AV_LOG_ERROR, "Requested input sample format %d is invalid\n", s->in_sample_fmt);
 170         return AVERROR(EINVAL);
 171     }
 172     if(s->out_sample_fmt >= AV_SAMPLE_FMT_NB){
 173         av_log(s, AV_LOG_ERROR, "Requested output sample format %d is invalid\n", s->out_sample_fmt);
 174         return AVERROR(EINVAL);
 175     }
 176
 177     if(   s->int_sample_fmt != AV_SAMPLE_FMT_S16
 178         &&s->int_sample_fmt != AV_SAMPLE_FMT_FLT){
 179         av_log(s, AV_LOG_ERROR, "Requested sample format %s is not supported internally, only float & S16 is supported\n", av_get_sample_fmt_name(s->int_sample_fmt));
 180         return AVERROR(EINVAL);
 181     }
 182
 183     //FIXME should we allow/support using FLT on material that doesnt need it ?
 184     if(s->in_sample_fmt <= AV_SAMPLE_FMT_S16 || s->int_sample_fmt==AV_SAMPLE_FMT_S16){
 185         s->int_sample_fmt= AV_SAMPLE_FMT_S16;
 186     }else
 187         s->int_sample_fmt= AV_SAMPLE_FMT_FLT;
 188
 189
 190     if (s->out_sample_rate!=s->in_sample_rate || (s->flags & SWR_FLAG_RESAMPLE)){
 191         s->resample = swri_resample_init(s->resample, s->out_sample_rate, s->in_sample_rate, 16, 10, 0, 0.8);
 192     }else
 193         swri_resample_free(&s->resample);
 194     if(s->int_sample_fmt != AV_SAMPLE_FMT_S16 && s->resample){
 195         av_log(s, AV_LOG_ERROR, "Resampling only supported with internal s16 currently\n"); //FIXME
 196         return -1;
 197     }
 198
 199     if(!s->used_ch_count)
 200         s->used_ch_count= s->in.ch_count;
 201
 202     if(s->used_ch_count && s-> in_ch_layout && s->used_ch_count != av_get_channel_layout_nb_channels(s-> in_ch_layout)){
 203         av_log(s, AV_LOG_WARNING, "Input channel layout has a different number of channels than the number of used channels, ignoring layout\n");
 204         s-> in_ch_layout= 0;
 205     }
 206
 207     if(!s-> in_ch_layout)
 208         s-> in_ch_layout= av_get_default_channel_layout(s->used_ch_count);
 209     if(!s->out_ch_layout)
 210         s->out_ch_layout= av_get_default_channel_layout(s->out.ch_count);
 211
 212     s->rematrix= s->out_ch_layout  !=s->in_ch_layout || s->rematrix_volume!=1.0 ||
 213                  s->rematrix_custom;
 214
 215 #define RSC 1 //FIXME finetune
 216     if(!s-> in.ch_count)
 217         s-> in.ch_count= av_get_channel_layout_nb_channels(s-> in_ch_layout);
 218     if(!s->used_ch_count)
 219         s->used_ch_count= s->in.ch_count;
 220     if(!s->out.ch_count)
 221         s->out.ch_count= av_get_channel_layout_nb_channels(s->out_ch_layout);
 222
 223     if(!s-> in.ch_count){
 224         av_assert0(!s->in_ch_layout);
 225         av_log(s, AV_LOG_ERROR, "Input channel count and layout are unset\n");
 226         return -1;
 227     }
 228
 229     if ((!s->out_ch_layout || !s->in_ch_layout) && s->used_ch_count != s->out.ch_count && !s->rematrix_custom) {
 230         av_log(s, AV_LOG_ERROR, "Rematrix is needed but there is not enough information to do it\n");
 231         return -1;
 232     }
 233
 234 av_assert0(s->used_ch_count);
 235 av_assert0(s->out.ch_count);
 236     s->resample_first= RSC*s->out.ch_count/s->in.ch_count - RSC < s->out_sample_rate/(float)s-> in_sample_rate - 1.0;
 237
 238     s-> in.bps= av_get_bytes_per_sample(s-> in_sample_fmt);
 239     s->int_bps= av_get_bytes_per_sample(s->int_sample_fmt);
 240     s->out.bps= av_get_bytes_per_sample(s->out_sample_fmt);
 241
 242     if(!s->resample && !s->rematrix && !s->channel_map){
 243         s->full_convert = swri_audio_convert_alloc(s->out_sample_fmt,
 244                                                    s-> in_sample_fmt, s-> in.ch_count, NULL, 0);
 245         return 0;
 246     }
 247
 248     s->in_convert = swri_audio_convert_alloc(s->int_sample_fmt,
 249                                              s-> in_sample_fmt, s->used_ch_count, s->channel_map, 0);
 250     s->out_convert= swri_audio_convert_alloc(s->out_sample_fmt,
 251                                              s->int_sample_fmt, s->out.ch_count, NULL, 0);
 252
 253
 254     s->postin= s->in;
 255     s->preout= s->out;
 256     s->midbuf= s->in;
 257     s->in_buffer= s->in;
 258     if(s->channel_map){
 259         s->postin.ch_count=
 260         s->midbuf.ch_count=
 261         s->in_buffer.ch_count= s->used_ch_count;
 262     }
 263     if(!s->resample_first){
 264         s->midbuf.ch_count= s->out.ch_count;
 265         s->in_buffer.ch_count = s->out.ch_count;
 266     }
 267
 268     s->in_buffer.bps = s->postin.bps = s->midbuf.bps = s->preout.bps =  s->int_bps;
 269     s->in_buffer.planar = s->postin.planar = s->midbuf.planar = s->preout.planar =  1;
 270
 271
 272     if(s->rematrix)
 273         return swri_rematrix_init(s);
 274
 275     return 0;
 276 }
 277
 278 static int realloc_audio(AudioData *a, int count){
 279     int i, countb;
 280     AudioData old;
 281
 282     if(a->count >= count)
 283         return 0;
 284
 285     count*=2;
 286
 287     countb= FFALIGN(count*a->bps, 32);
 288     old= *a;
 289
 290     av_assert0(a->planar);
 291     av_assert0(a->bps);
 292     av_assert0(a->ch_count);
 293
 294     a->data= av_malloc(countb*a->ch_count);
 295     if(!a->data)
 296         return AVERROR(ENOMEM);
 297     for(i=0; i<a->ch_count; i++){
 298         a->ch[i]= a->data + i*(a->planar ? countb : a->bps);
 299         if(a->planar) memcpy(a->ch[i], old.ch[i], a->count*a->bps);
 300     }
 301     av_free(old.data);
 302     a->count= count;
 303
 304     return 1;
 305 }
 306
 307 static void copy(AudioData *out, AudioData *in,
 308                  int count){
 309     av_assert0(out->planar == in->planar);
 310     av_assert0(out->bps == in->bps);
 311     av_assert0(out->ch_count == in->ch_count);
 312     if(out->planar){
 313         int ch;
 314         for(ch=0; ch<out->ch_count; ch++)
 315             memcpy(out->ch[ch], in->ch[ch], count*out->bps);
 316     }else
 317         memcpy(out->ch[0], in->ch[0], count*out->ch_count*out->bps);
 318 }
 319
 320 static void fill_audiodata(AudioData *out, uint8_t *in_arg [SWR_CH_MAX]){
 321     int i;
 322     if(out->planar){
 323         for(i=0; i<out->ch_count; i++)
 324             out->ch[i]= in_arg[i];
 325     }else{
 326         for(i=0; i<out->ch_count; i++)
 327             out->ch[i]= in_arg[0] + i*out->bps;
 328     }
 329 }
 330
 331 /**
 332  *
 333  * out may be equal in.
 334  */
 335 static void buf_set(AudioData *out, AudioData *in, int count){
 336     if(in->planar){
 337         int ch;
 338         for(ch=0; ch<out->ch_count; ch++)
 339             out->ch[ch]= in->ch[ch] + count*out->bps;
 340     }else
 341         out->ch[0]= in->ch[0] + count*out->ch_count*out->bps;
 342 }
 343
 344 /**
 345  *
 346  * @return number of samples output per channel
 347  */
 348 static int resample(SwrContext *s, AudioData *out_param, int out_count,
 349                              const AudioData * in_param, int in_count){
 350     AudioData in, out, tmp;
 351     int ret_sum=0;
 352     int border=0;
 353
 354     tmp=out=*out_param;
 355     in =  *in_param;
 356
 357     do{
 358         int ret, size, consumed;
 359         if(!s->resample_in_constraint && s->in_buffer_count){
 360             buf_set(&tmp, &s->in_buffer, s->in_buffer_index);
 361             ret= swri_multiple_resample(s->resample, &out, out_count, &tmp, s->in_buffer_count, &consumed);
 362             out_count -= ret;
 363             ret_sum += ret;
 364             buf_set(&out, &out, ret);
 365             s->in_buffer_count -= consumed;
 366             s->in_buffer_index += consumed;
 367
 368             if(!in_count)
 369                 break;
 370             if(s->in_buffer_count <= border){
 371                 buf_set(&in, &in, -s->in_buffer_count);
 372                 in_count += s->in_buffer_count;
 373                 s->in_buffer_count=0;
 374                 s->in_buffer_index=0;
 375                 border = 0;
 376             }
 377         }
 378
 379         if(in_count && !s->in_buffer_count){
 380             s->in_buffer_index=0;
 381             ret= swri_multiple_resample(s->resample, &out, out_count, &in, in_count, &consumed);
 382             out_count -= ret;
 383             ret_sum += ret;
 384             buf_set(&out, &out, ret);
 385             in_count -= consumed;
 386             buf_set(&in, &in, consumed);
 387         }
 388
 389         //TODO is this check sane considering the advanced copy avoidance below
 390         size= s->in_buffer_index + s->in_buffer_count + in_count;
 391         if(   size > s->in_buffer.count
 392            && s->in_buffer_count + in_count <= s->in_buffer_index){
 393             buf_set(&tmp, &s->in_buffer, s->in_buffer_index);
 394             copy(&s->in_buffer, &tmp, s->in_buffer_count);
 395             s->in_buffer_index=0;
 396         }else
 397             if((ret=realloc_audio(&s->in_buffer, size)) < 0)
 398                 return ret;
 399
 400         if(in_count){
 401             int count= in_count;
 402             if(s->in_buffer_count && s->in_buffer_count+2 < count && out_count) count= s->in_buffer_count+2;
 403
 404             buf_set(&tmp, &s->in_buffer, s->in_buffer_index + s->in_buffer_count);
 405             copy(&tmp, &in, /*in_*/count);
 406             s->in_buffer_count += count;
 407             in_count -= count;
 408             border += count;
 409             buf_set(&in, &in, count);
 410             s->resample_in_constraint= 0;
 411             if(s->in_buffer_count != count || in_count)
 412                 continue;
 413         }
 414         break;
 415     }while(1);
 416
 417     s->resample_in_constraint= !!out_count;
 418
 419     return ret_sum;
 420 }
 421
 422 int swr_convert(struct SwrContext *s, uint8_t *out_arg[SWR_CH_MAX], int out_count,
 423                          const uint8_t *in_arg [SWR_CH_MAX], int  in_count){
 424     AudioData *postin, *midbuf, *preout;
 425     int ret/*, in_max*/;
 426     AudioData * in= &s->in;
 427     AudioData *out= &s->out;
 428     AudioData preout_tmp, midbuf_tmp;
 429
 430     if(!s->resample){
 431         if(in_count > out_count)
 432             return -1;
 433         out_count = in_count;
 434     }
 435
 436     if(!in_arg){
 437         if(s->in_buffer_count){
 438             AudioData *a= &s->in_buffer;
 439             int i, j, ret;
 440             if((ret=realloc_audio(a, s->in_buffer_index + 2*s->in_buffer_count)) < 0)
 441                 return ret;
 442             av_assert0(a->planar);
 443             for(i=0; i<a->ch_count; i++){
 444                 for(j=0; j<s->in_buffer_count; j++){
 445                     memcpy(a->ch[i] + (s->in_buffer_index+s->in_buffer_count+j  )*a->bps,
 446                            a->ch[i] + (s->in_buffer_index+s->in_buffer_count-j-1)*a->bps, a->bps);
 447                 }
 448             }
 449             s->in_buffer_count += (s->in_buffer_count+1)/2;
 450             s->resample_in_constraint = 0;
 451         }else{
 452             return 0;
 453         }
 454     }else
 455         fill_audiodata(in ,  (void*)in_arg);
 456     fill_audiodata(out, out_arg);
 457
 458     if(s->full_convert){
 459         av_assert0(!s->resample);
 460         swri_audio_convert(s->full_convert, out, in, in_count);
 461         return out_count;
 462     }
 463
 464 //     in_max= out_count*(int64_t)s->in_sample_rate / s->out_sample_rate + resample_filter_taps;
 465 //     in_count= FFMIN(in_count, in_in + 2 - s->hist_buffer_count);
 466
 467     if((ret=realloc_audio(&s->postin, in_count))<0)
 468         return ret;
 469     if(s->resample_first){
 470         av_assert0(s->midbuf.ch_count == s->used_ch_count);
 471         if((ret=realloc_audio(&s->midbuf, out_count))<0)
 472             return ret;
 473     }else{
 474         av_assert0(s->midbuf.ch_count ==  s->out.ch_count);
 475         if((ret=realloc_audio(&s->midbuf,  in_count))<0)
 476             return ret;
 477     }
 478     if((ret=realloc_audio(&s->preout, out_count))<0)
 479         return ret;
 480
 481     postin= &s->postin;
 482
 483     midbuf_tmp= s->midbuf;
 484     midbuf= &midbuf_tmp;
 485     preout_tmp= s->preout;
 486     preout= &preout_tmp;
 487
 488     if(s->int_sample_fmt == s-> in_sample_fmt && s->in.planar)
 489         postin= in;
 490
 491     if(s->resample_first ? !s->resample : !s->rematrix)
 492         midbuf= postin;
 493
 494     if(s->resample_first ? !s->rematrix : !s->resample)
 495         preout= midbuf;
 496
 497     if(s->int_sample_fmt == s->out_sample_fmt && s->out.planar){
 498         if(preout==in){
 499             out_count= FFMIN(out_count, in_count); //TODO check at the end if this is needed or redundant
 500             av_assert0(s->in.planar); //we only support planar internally so it has to be, we support copying non planar though
 501             copy(out, in, out_count);
 502             return out_count;
 503         }
 504         else if(preout==postin) preout= midbuf= postin= out;
 505         else if(preout==midbuf) preout= midbuf= out;
 506         else                    preout= out;
 507     }
 508
 509     if(in != postin){
 510         swri_audio_convert(s->in_convert, postin, in, in_count);
 511     }
 512
 513     if(s->resample_first){
 514         if(postin != midbuf)
 515             out_count= resample(s, midbuf, out_count, postin, in_count);
 516         if(midbuf != preout)
 517             swri_rematrix(s, preout, midbuf, out_count, preout==out);
 518     }else{
 519         if(postin != midbuf)
 520             swri_rematrix(s, midbuf, postin, in_count, midbuf==out);
 521         if(midbuf != preout)
 522             out_count= resample(s, preout, out_count, midbuf, in_count);
 523     }
 524
 525     if(preout != out){
 526 //FIXME packed doesnt need more than 1 chan here!
 527         swri_audio_convert(s->out_convert, out, preout, out_count);
 528     }
 529     if(!in_arg)
 530         s->in_buffer_count = 0;
 531     return out_count;
 532 }
 533