ref: 8dfba387f8e72aa921b39c785bce9a8ef219bbf8
dir: /src/opusenc.c/
/* Copyright (c) 2002-2011 Jean-Marc Valin
Copyright (c) 2007-2011 Xiph.Org Foundation
Copyright (c) 2008-2010 Gregory Maxwell
File: opusenc.c
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
- Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
- Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <stdio.h>
#include <getopt.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include "opus_header.h"
#include "speex_resampler.h"
#ifdef _MSC_VER
#define snprintf _snprintf
#endif
#include "opus.h"
#include "opus_multistream.h"
#include "opus_header.h"
#include <ogg/ogg.h>
#include "wav_io.h"
#if defined WIN32 || defined _WIN32
/* We need the following two to set stdout to binary */
#include <io.h>
#include <fcntl.h>
#endif
void comment_init(char **comments, int* length, char *vendor_string);
void comment_add(char **comments, int* length, char *tag, char *val);
/*Write an Ogg page to a file pointer*/
int oe_write_page(ogg_page *page, FILE *fp)
{
int written;
written = fwrite(page->header,1,page->header_len, fp);
written += fwrite(page->body,1,page->body_len, fp);
return written;
}
#define MAX_FRAME_SIZE (960*2*3)
#define MAX_FRAME_BYTES 1276
#define IMIN(a,b) ((a) < (b) ? (a) : (b)) /**< Minimum int value. */
#define IMAX(a,b) ((a) > (b) ? (a) : (b)) /**< Maximum int value. */
/* Convert input audio bits, endians and channels */
static int read_samples_pcm(FILE *fin,int frame_size, int bits, int channels,
int lsb, float * input, char *buff, opus_int32 *size,
int *extra_samples)
{
short s[MAX_FRAME_SIZE];
unsigned char *in = (unsigned char*)s;
int i;
int nb_read;
int extra=0;
/*Read input audio*/
if (buff)
{
for (i=0;i<12;i++)
in[i]=buff[i];
nb_read = fread(in+12, 1, bits/8*channels*frame_size-12, fin) + 12;
if (size)
*size += 12;
} else {
int tmp = frame_size;
if (size && tmp > *size)
tmp = *size;
nb_read = fread(in, 1, bits/8*channels* tmp, fin);
}
nb_read /= bits/8*channels;
/* Make sure to return *extra_samples zeros at the end */
if (nb_read<frame_size)
{
extra = frame_size-nb_read;
if (extra > *extra_samples)
extra = *extra_samples;
*extra_samples -= extra;
}
/*fprintf (stderr, "%d\n", nb_read);*/
if (nb_read==0 && extra==0)
return 0;
if(bits==8)
{
/* Convert 8->16 bits */
for(i=frame_size*channels-1;i>=0;i--)
{
s[i]=(in[i]<<8)^0x8000;
}
} else
{
/* convert to our endian format */
for(i=0;i<frame_size*channels;i++)
{
if(lsb)
s[i]=le_short(s[i]);
else
s[i]=be_short(s[i]);
}
}
/* copy to float input buffer */
for (i=0;i<frame_size*channels;i++)
{
input[i]=s[i]*(1/32768.f);
}
for (i=nb_read*channels;i<frame_size*channels;i++)
{
input[i]=0;
}
nb_read += extra;
if (size)
{
int tmp = bits/8*channels*nb_read;
if (tmp > *size)
*size = 0;
else
*size -= tmp;
}
return nb_read;
}
static int read_samples(FILE *fin,int frame_size, int bits, int channels,
int lsb, float * input, char *buff, opus_int32 *size,
SpeexResamplerState *resampler, int *extra_samples)
{
if (resampler)
{
/* FIXME: This is a hack, get rid of these static variables */
static float pcmbuf[2048];
static int inbuf=0;
int out_samples=0;
while (out_samples<frame_size)
{
int i;
int reading, ret;
unsigned in_len, out_len;
reading = 1024-inbuf;
ret = read_samples_pcm(fin, reading, bits, channels, lsb, pcmbuf+inbuf*channels, buff, size, extra_samples);
inbuf += ret;
in_len = inbuf;
out_len = frame_size-out_samples;
speex_resampler_process_interleaved_float(resampler, pcmbuf, &in_len, input+out_samples*channels, &out_len);
if (ret==0 && in_len==0)
{
for (i=out_samples*channels;i<frame_size*channels;i++)
input[i] = 0;
return out_samples;
}
out_samples += out_len;
for (i=0;i<channels*(inbuf-in_len);i++)
pcmbuf[i] = pcmbuf[i+channels*in_len];
inbuf -= in_len;
}
return out_samples;
} else {
return read_samples_pcm(fin, frame_size, bits, channels, lsb, input, buff, size, extra_samples);
}
}
void version(const char *version)
{
printf ("opusenc (based on %s)\n",version);
printf ("Copyright (C) 2008-2011 Xiph.Org Foundation (written by Jean-Marc Valin)\n");
}
void version_short(const char *version)
{
printf ("opusenc (based on %s)\n",version);
printf ("Copyright (C) 2008-2011 Xiph.Org Foundation (written by Jean-Marc Valin)\n");
}
void usage(void)
{
printf ("Usage: opusenc [options] input_file output_file.oga\n");
printf ("\n");
printf ("Encodes input_file using Opus. It can read the WAV or raw files.\n");
printf ("\n");
printf ("input_file can be:\n");
printf (" filename.wav wav file\n");
printf (" filename.* Raw PCM file (any extension other than .wav)\n");
printf (" - stdin\n");
printf ("\n");
printf ("output_file can be:\n");
printf (" filename.oga compressed file\n");
printf (" - stdout\n");
printf ("\n");
printf ("Options:\n");
printf (" --speech Optimize for speech\n");
printf (" --music Optimize for music\n");
printf (" --bitrate n Encoding bit-rate in kbit/sec\n");
printf (" --cbr Use constant bitrate encoding\n");
printf (" --comp n Encoding complexity (0-10)\n");
printf (" --framesize n Frame size (Default: 960)\n");
printf (" --nopf Do not use the prefilter/postfilter\n");
printf (" --independent Encode frames independently (implies nopf)\n");
printf (" --comment Add the given string as an extra comment. This may be\n");
printf (" used multiple times\n");
printf (" --author Author of this track\n");
printf (" --title Title for this track\n");
printf (" -h, --help This help\n");
printf (" -v, --version Version information\n");
printf (" -V Verbose mode (show bit-rate)\n");
printf ("Raw input options:\n");
printf (" --rate n Sampling rate for raw input\n");
printf (" --mono Consider raw input as mono\n");
printf (" --stereo Consider raw input as stereo\n");
printf (" --le Raw input is little-endian\n");
printf (" --be Raw input is big-endian\n");
printf (" --8bit Raw input is 8-bit unsigned\n");
printf (" --16bit Raw input is 16-bit signed\n");
printf ("Default raw PCM input is 48kHz, 16-bit, little-endian, stereo\n");
}
int main(int argc, char **argv)
{
int nb_samples, total_samples=0, nb_encoded;
int c;
int option_index = 0;
char *inFile, *outFile;
FILE *fin, *fout;
float input[MAX_FRAME_SIZE];
opus_int32 frame_size = 960;
int quiet=0;
int nbBytes;
OpusMSEncoder *st;
unsigned char bits[MAX_FRAME_BYTES];
int with_cbr = 0;
int with_cvbr = 0;
int total_bytes = 0;
int peak_bytes = 0;
struct option long_options[] =
{
{"bitrate", required_argument, NULL, 0},
{"cbr",no_argument,NULL, 0},
{"cvbr",no_argument,NULL, 0},
{"comp", required_argument, NULL, 0},
{"nopf", no_argument, NULL, 0},
{"independent", no_argument, NULL, 0},
{"framesize", required_argument, NULL, 0},
{"help", no_argument, NULL, 0},
{"quiet", no_argument, NULL, 0},
{"le", no_argument, NULL, 0},
{"be", no_argument, NULL, 0},
{"8bit", no_argument, NULL, 0},
{"16bit", no_argument, NULL, 0},
{"mono", no_argument, NULL, 0},
{"stereo", no_argument, NULL, 0},
{"rate", required_argument, NULL, 0},
{"music", no_argument, NULL, 0},
{"speech", no_argument, NULL, 0},
{"version", no_argument, NULL, 0},
{"version-short", no_argument, NULL, 0},
{"comment", required_argument, NULL, 0},
{"author", required_argument, NULL, 0},
{"title", required_argument, NULL, 0},
{0, 0, 0, 0}
};
int print_bitrate=0;
opus_int32 rate=48000;
opus_int32 size;
int chan=1;
int fmt=16;
int lsb=1;
ogg_stream_state os;
ogg_page og;
ogg_packet op;
ogg_int64_t last_granulepos = 0;
int bytes_written=0, ret, result;
int id=-1;
OpusHeader header;
char vendor_string[64];
char *comments;
int comments_length;
int close_in=0, close_out=0;
int eos=0;
float bitrate=-1;
char first_bytes[12];
int wave_input=0;
opus_int32 lookahead = 0;
int bytes_per_packet=-1;
int complexity=-127;
const char *opus_version;
SpeexResamplerState *resampler=NULL;
int extra_samples;
int signal = OPUS_SIGNAL_AUTO;
unsigned char mapping[256] = {0, 1};
opus_version = opus_get_version_string();
snprintf(vendor_string, sizeof(vendor_string), "%s\n",opus_version);
comment_init(&comments, &comments_length, vendor_string);
/*Process command-line options*/
while(1)
{
c = getopt_long (argc, argv, "hvV",
long_options, &option_index);
if (c==-1)
break;
switch(c)
{
case 0:
if (strcmp(long_options[option_index].name,"bitrate")==0)
{
bitrate = atof (optarg);
} else if (strcmp(long_options[option_index].name,"cbr")==0)
{
with_cbr=1;
} else if (strcmp(long_options[option_index].name,"cvbr")==0)
{
with_cvbr=1;
} else if (strcmp(long_options[option_index].name,"help")==0)
{
usage();
exit(0);
} else if (strcmp(long_options[option_index].name,"quiet")==0)
{
quiet = 1;
} else if (strcmp(long_options[option_index].name,"version")==0)
{
version(opus_version);
exit(0);
} else if (strcmp(long_options[option_index].name,"version-short")==0)
{
version_short(opus_version);
exit(0);
} else if (strcmp(long_options[option_index].name,"le")==0)
{
lsb=1;
} else if (strcmp(long_options[option_index].name,"be")==0)
{
lsb=0;
} else if (strcmp(long_options[option_index].name,"8bit")==0)
{
fmt=8;
} else if (strcmp(long_options[option_index].name,"16bit")==0)
{
fmt=16;
} else if (strcmp(long_options[option_index].name,"stereo")==0)
{
chan=2;
} else if (strcmp(long_options[option_index].name,"mono")==0)
{
chan=1;
} else if (strcmp(long_options[option_index].name,"rate")==0)
{
rate=atoi (optarg);
} else if (strcmp(long_options[option_index].name,"music")==0)
{
signal = OPUS_SIGNAL_MUSIC;
} else if (strcmp(long_options[option_index].name,"speech")==0)
{
signal = OPUS_SIGNAL_VOICE;
} else if (strcmp(long_options[option_index].name,"comp")==0)
{
complexity=atoi (optarg);
} else if (strcmp(long_options[option_index].name,"framesize")==0)
{
frame_size=atoi (optarg);
} else if (strcmp(long_options[option_index].name,"comment")==0)
{
if (!strchr(optarg, '='))
{
fprintf (stderr, "Invalid comment: %s\n", optarg);
fprintf (stderr, "Comments must be of the form name=value\n");
exit(1);
}
comment_add(&comments, &comments_length, NULL, optarg);
} else if (strcmp(long_options[option_index].name,"author")==0)
{
comment_add(&comments, &comments_length, "author=", optarg);
} else if (strcmp(long_options[option_index].name,"title")==0)
{
comment_add(&comments, &comments_length, "title=", optarg);
}
break;
case 'h':
usage();
exit(0);
break;
case 'v':
version(opus_version);
exit(0);
break;
case 'V':
print_bitrate=1;
break;
case '?':
usage();
exit(1);
break;
}
}
if (argc-optind!=2)
{
usage();
exit(1);
}
inFile=argv[optind];
outFile=argv[optind+1];
/*Initialize Ogg stream struct*/
srand(time(NULL));
if (ogg_stream_init(&os, rand())==-1)
{
fprintf(stderr,"Error: stream init failed\n");
exit(1);
}
if (strcmp(inFile, "-")==0)
{
#if defined WIN32 || defined _WIN32
_setmode(_fileno(stdin), _O_BINARY);
#elif defined OS2
_fsetmode(stdin,"b");
#endif
fin=stdin;
}
else
{
fin = fopen(inFile, "rb");
if (!fin)
{
perror(inFile);
exit(1);
}
close_in=1;
}
{
int ret;
ret = fread(first_bytes, 1, 12, fin);
if (strncmp(first_bytes,"RIFF",4)==0 && strncmp(first_bytes,"RIFF",4)==0)
{
if (read_wav_header(fin, &rate, &chan, &fmt, &size)==-1)
exit(1);
wave_input=1;
lsb=1; /* CHECK: exists big-endian .wav ?? */
}
}
if (rate != 48000)
{
int err;
fprintf(stderr, "Resampling from %d Hz to %d Hz before encoding\n", rate, 48000);
resampler = speex_resampler_init(chan, rate, 48000, 5, &err);
if (err!=0)
fprintf(stderr, "resampler error: %s\n", speex_resampler_strerror(err));
/* Using pre-skip to skip the zeros */
/*speex_resampler_skip_zeros(resampler);*/
}
if (bitrate<=0.005)
{
if (chan==1)
bitrate=64.0;
else
bitrate=128.0;
}
bytes_per_packet = MAX_FRAME_BYTES;
/*Initialize OPUS encoder*/
st = opus_multistream_encoder_create(48000, chan, 1, chan==2, mapping, OPUS_APPLICATION_AUDIO);
opus_multistream_encoder_ctl(st, OPUS_SET_SIGNAL(signal));
header.channels = chan;
opus_multistream_encoder_ctl(st, OPUS_GET_LOOKAHEAD(&lookahead));
header.preskip = lookahead;
if (resampler)
header.preskip += speex_resampler_get_output_latency(resampler);
header.channel_mapping = 0;
header.nb_streams = 1;
header.nb_coupled = 1;
/* 0 dB gain is the recommended unless you know what you're doing */
header.gain = 0;
header.input_sample_rate = rate;
/* Extra samples that need to be read to compensate for the pre-skip */
extra_samples = (int)header.preskip * (rate/48000.);
{
char *st_string="mono";
if (chan==2)
st_string="stereo";
if (!quiet)
{
if (with_cbr)
fprintf (stderr, "Encoding %.0f kHz %s audio in %.0fms packets at %0.3fkbit/sec (%d bytes per packet, CBR)\n",
header.input_sample_rate/1000., st_string, frame_size/48., bitrate, bytes_per_packet);
else
fprintf (stderr, "Encoding %.0f kHz %s audio in %.0fms packets at %0.3fkbit/sec (%d bytes per packet maximum)\n",
header.input_sample_rate/1000., st_string, frame_size/48., bitrate, bytes_per_packet);
}
}
{
int tmp = (bitrate*1000);
if (opus_multistream_encoder_ctl(st, OPUS_SET_BITRATE(tmp)) != OPUS_OK)
{
fprintf (stderr, "bitrate request failed\n");
return 1;
}
}
if (!with_cbr)
{
if (opus_multistream_encoder_ctl(st, OPUS_SET_VBR(1)) != OPUS_OK)
{
fprintf (stderr, "VBR request failed\n");
return 1;
}
if (!with_cvbr)
{
if (opus_multistream_encoder_ctl(st, OPUS_SET_VBR_CONSTRAINT(0)) != OPUS_OK)
{
fprintf (stderr, "VBR constraint failed\n");
return 1;
}
}
}
if (complexity!=-127) {
if (opus_multistream_encoder_ctl(st, OPUS_SET_COMPLEXITY(complexity)) != OPUS_OK)
{
fprintf (stderr, "Only complexity 0 through 10 is supported\n");
return 1;
}
}
if (strcmp(outFile,"-")==0)
{
#if defined WIN32 || defined _WIN32
_setmode(_fileno(stdout), _O_BINARY);
#endif
fout=stdout;
}
else
{
fout = fopen(outFile, "wb");
if (!fout)
{
perror(outFile);
exit(1);
}
close_out=1;
}
/*Write header*/
{
unsigned char header_data[100];
int packet_size = opus_header_to_packet(&header, header_data, 100);
op.packet = header_data;
op.bytes = packet_size;
op.b_o_s = 1;
op.e_o_s = 0;
op.granulepos = 0;
op.packetno = 0;
ogg_stream_packetin(&os, &op);
while((result = ogg_stream_flush(&os, &og)))
{
if(!result) break;
ret = oe_write_page(&og, fout);
if(ret != og.header_len + og.body_len)
{
fprintf (stderr,"Error: failed writing header to output stream\n");
exit(1);
}
else
bytes_written += ret;
}
op.packet = (unsigned char *)comments;
op.bytes = comments_length;
op.b_o_s = 0;
op.e_o_s = 0;
op.granulepos = 0;
op.packetno = 1;
ogg_stream_packetin(&os, &op);
}
/* writing the rest of the opus header packets */
while((result = ogg_stream_flush(&os, &og)))
{
if(!result) break;
ret = oe_write_page(&og, fout);
if(ret != og.header_len + og.body_len)
{
fprintf (stderr,"Error: failed writing header to output stream\n");
exit(1);
}
else
bytes_written += ret;
}
free(comments);
if (!wave_input)
{
nb_samples = read_samples(fin,frame_size,fmt,chan,lsb,input, first_bytes, NULL, resampler, &extra_samples);
} else {
nb_samples = read_samples(fin,frame_size,fmt,chan,lsb,input, NULL, &size, resampler, &extra_samples);
}
if (nb_samples==0)
eos=1;
total_samples += nb_samples;
nb_encoded = -header.preskip;
/*Main encoding loop (one frame per iteration)*/
while (!eos)
{
id++;
/*Encode current frame*/
nbBytes = opus_multistream_encode_float(st, input, frame_size, bits, bytes_per_packet);
if (nbBytes<0)
{
fprintf(stderr, "Encoding failed: %s. Aborting.\n", opus_strerror(nbBytes));
break;
}
nb_encoded += frame_size;
total_bytes += nbBytes;
peak_bytes=IMAX(nbBytes,peak_bytes);
if (wave_input)
{
nb_samples = read_samples(fin,frame_size,fmt,chan,lsb,input, NULL, &size, resampler, &extra_samples);
} else {
nb_samples = read_samples(fin,frame_size,fmt,chan,lsb,input, NULL, NULL, resampler, &extra_samples);
}
if (nb_samples==0)
{
eos=1;
}
if (eos && total_samples<=nb_encoded)
op.e_o_s = 1;
else
op.e_o_s = 0;
total_samples += nb_samples;
op.packet = (unsigned char *)bits;
op.bytes = nbBytes;
op.b_o_s = 0;
/*Is this redundent?*/
if (eos && total_samples<=nb_encoded)
op.e_o_s = 1;
else
op.e_o_s = 0;
op.granulepos = (id+1)*frame_size;
if (op.granulepos>total_samples)
op.granulepos = total_samples;
op.packetno = 2+id;
/*printf ("granulepos: %d %d %d\n", (int)op.granulepos, op.packetno, op.bytes);*/
ogg_stream_packetin(&os, &op);
/*Write all new pages (most likely 0 or 1)
Flush if we've buffered 1 second to avoid excessive framing delay. */
while (eos||(op.granulepos-last_granulepos+MAX_FRAME_SIZE>48000)?
#if 0
/*Libogg > 1.2.2 allows us to achieve lower overhead by
producing larger pages. For 20ms frames this is only relevant
above ~32kbit/sec. We still target somewhat smaller than the
maximum size in order to avoid continued pages.*/
ogg_stream_flush_fill(&os, &og,255*255-7*MAX_FRAME_BYTES):
ogg_stream_pageout_fill(&os, &og,255*255-7*MAX_FRAME_BYTES))
#else
ogg_stream_flush(&os, &og):
ogg_stream_pageout(&os, &og))
#endif
{
if (ogg_page_packets(&og)!=0)
last_granulepos = ogg_page_granulepos(&og);
ret = oe_write_page(&og, fout);
if(ret != og.header_len + og.body_len)
{
fprintf (stderr,"Error: failed writing header to output stream\n");
exit(1);
}
else
bytes_written += ret;
}
}
/*Flush all pages left to be written*/
while (ogg_stream_flush(&os, &og))
{
ret = oe_write_page(&og, fout);
if(ret != og.header_len + og.body_len)
{
fprintf (stderr,"Error: failed writing header to output stream\n");
exit(1);
}
else
bytes_written += ret;
}
if (!with_cbr && !quiet)
fprintf (stderr, "Average rate %0.3fkbit/sec, %d peak bytes per packet\n", (total_bytes*8.0/((float)nb_encoded/header.input_sample_rate))/1000.0, peak_bytes);
opus_multistream_encoder_destroy(st);
ogg_stream_clear(&os);
if (close_in)
fclose(fin);
if (close_out)
fclose(fout);
return 0;
}
/*
Comments will be stored in the Vorbis style.
It is describled in the "Structure" section of
http://www.xiph.org/ogg/vorbis/doc/v-comment.html
The comment header is decoded as follows:
1) [vendor_length] = read an unsigned integer of 32 bits
2) [vendor_string] = read a UTF-8 vector as [vendor_length] octets
3) [user_comment_list_length] = read an unsigned integer of 32 bits
4) iterate [user_comment_list_length] times {
5) [length] = read an unsigned integer of 32 bits
6) this iteration's user comment = read a UTF-8 vector as [length] octets
}
7) [framing_bit] = read a single bit as boolean
8) if ( [framing_bit] unset or end of packet ) then ERROR
9) done.
If you have troubles, please write to ymnk@jcraft.com.
*/
#define readint(buf, base) (((buf[base+3]<<24)&0xff000000)| \
((buf[base+2]<<16)&0xff0000)| \
((buf[base+1]<<8)&0xff00)| \
(buf[base]&0xff))
#define writeint(buf, base, val) do{ buf[base+3]=((val)>>24)&0xff; \
buf[base+2]=((val)>>16)&0xff; \
buf[base+1]=((val)>>8)&0xff; \
buf[base]=(val)&0xff; \
}while(0)
void comment_init(char **comments, int* length, char *vendor_string)
{
int vendor_length=strlen(vendor_string);
int user_comment_list_length=0;
int len=8+4+vendor_length+4;
char *p=(char*)malloc(len);
if(p==NULL){
fprintf (stderr, "malloc failed in comment_init()\n");
exit(1);
}
memcpy(p, "OpusTags", 8);
writeint(p, 8, vendor_length);
memcpy(p+12, vendor_string, vendor_length);
writeint(p, 12+vendor_length, user_comment_list_length);
*length=len;
*comments=p;
}
void comment_add(char **comments, int* length, char *tag, char *val)
{
char* p=*comments;
int vendor_length=readint(p, 0);
int user_comment_list_length=readint(p, 4+vendor_length);
int tag_len=(tag?strlen(tag):0);
int val_len=strlen(val);
int len=(*length)+4+tag_len+val_len;
p=(char*)realloc(p, len);
if(p==NULL){
fprintf (stderr, "realloc failed in comment_add()\n");
exit(1);
}
writeint(p, *length, tag_len+val_len); /* length of comment */
if(tag) memcpy(p+*length+4, tag, tag_len); /* comment */
memcpy(p+*length+4+tag_len, val, val_len); /* comment */
writeint(p, 4+vendor_length, user_comment_list_length+1);
*comments=p;
*length=len;
}
#undef readint
#undef writeint