ref: dc500a7ac53098c5b360c33936a2e74c6a99cbfc
dir: /src/opus_header.c/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include "opus_header.h"
#include <string.h>
#include <stdio.h>
/* Header contents:
- "OpusHead" (64 bits)
- version number (8 bits)
- Channels C (8 bits)
- Pre-skip (16 bits)
- Sampling rate (32 bits)
- Gain in dB (16 bits, S7.8)
- Mapping (8 bits, 0=single stream (mono/stereo) 1=Vorbis mapping,
2..254: reserved, 255: multistream with no mapping)
- if (mapping != 0)
- N = totel number of streams (8 bits)
- M = number of paired streams (8 bits)
- C times channel origin
- if (C<2*M)
- stream = byte/2
- if (byte&0x1 == 0)
- left
else
- right
- else
- stream = byte-M
*/
typedef struct {
unsigned char *data;
int maxlen;
int pos;
} Packet;
typedef struct {
const unsigned char *data;
int maxlen;
int pos;
} ROPacket;
static int write_uint32(Packet *p, ogg_uint32_t val)
{
if (p->pos>p->maxlen-4)
return 0;
p->data[p->pos ] = (val ) & 0xFF;
p->data[p->pos+1] = (val>> 8) & 0xFF;
p->data[p->pos+2] = (val>>16) & 0xFF;
p->data[p->pos+3] = (val>>24) & 0xFF;
p->pos += 4;
return 1;
}
static int write_uint16(Packet *p, ogg_uint16_t val)
{
if (p->pos>p->maxlen-2)
return 0;
p->data[p->pos ] = (val ) & 0xFF;
p->data[p->pos+1] = (val>> 8) & 0xFF;
p->pos += 2;
return 1;
}
static int write_chars(Packet *p, const unsigned char *str, int nb_chars)
{
int i;
if (p->pos>p->maxlen-nb_chars)
return 0;
for (i=0;i<nb_chars;i++)
p->data[p->pos++] = str[i];
return 1;
}
static int read_uint32(ROPacket *p, ogg_uint32_t *val)
{
if (p->pos>p->maxlen-4)
return 0;
*val = (ogg_uint32_t)p->data[p->pos ];
*val |= (ogg_uint32_t)p->data[p->pos+1]<< 8;
*val |= (ogg_uint32_t)p->data[p->pos+2]<<16;
*val |= (ogg_uint32_t)p->data[p->pos+3]<<24;
p->pos += 4;
return 1;
}
static int read_uint16(ROPacket *p, ogg_uint16_t *val)
{
if (p->pos>p->maxlen-2)
return 0;
*val = (ogg_uint16_t)p->data[p->pos ];
*val |= (ogg_uint16_t)p->data[p->pos+1]<<8;
p->pos += 2;
return 1;
}
static int read_chars(ROPacket *p, unsigned char *str, int nb_chars)
{
int i;
if (p->pos>p->maxlen-nb_chars)
return 0;
for (i=0;i<nb_chars;i++)
str[i] = p->data[p->pos++];
return 1;
}
int opus_header_parse(const unsigned char *packet, int len, OpusHeader *h)
{
int i;
char str[9];
ROPacket p;
unsigned char ch;
ogg_uint16_t shortval;
p.data = packet;
p.maxlen = len;
p.pos = 0;
str[8] = 0;
if (len<19)return 0;
read_chars(&p, (unsigned char*)str, 8);
if (memcmp(str, "OpusHead", 8)!=0)
return 0;
if (!read_chars(&p, &ch, 1))
return 0;
h->version = ch;
if((h->version&240) != 0) /* Only major version 0 supported. */
return 0;
if (!read_chars(&p, &ch, 1))
return 0;
h->channels = ch;
if (h->channels == 0)
return 0;
if (!read_uint16(&p, &shortval))
return 0;
h->preskip = shortval;
if (!read_uint32(&p, &h->input_sample_rate))
return 0;
if (!read_uint16(&p, &shortval))
return 0;
h->gain = (short)shortval;
if (!read_chars(&p, &ch, 1))
return 0;
h->channel_mapping = ch;
if (h->channel_mapping != 0)
{
if (!read_chars(&p, &ch, 1))
return 0;
if (ch<1)
return 0;
h->nb_streams = ch;
if (!read_chars(&p, &ch, 1))
return 0;
if (ch>h->nb_streams || (ch+h->nb_streams)>255)
return 0;
h->nb_coupled = ch;
/* Multi-stream support */
for (i=0;i<h->channels;i++)
{
if (!read_chars(&p, &h->stream_map[i], 1))
return 0;
if (h->stream_map[i]>(h->nb_streams+h->nb_coupled) && h->stream_map[i]!=255)
return 0;
}
} else {
if(h->channels>2)
return 0;
h->nb_streams = 1;
h->nb_coupled = h->channels>1;
h->stream_map[0]=0;
h->stream_map[1]=1;
}
/*For version 0/1 we know there won't be any more data
so reject any that have data past the end.*/
if ((h->version==0 || h->version==1) && p.pos != len)
return 0;
return 1;
}
int opus_header_to_packet(const OpusHeader *h, unsigned char *packet, int len)
{
int i;
Packet p;
unsigned char ch;
p.data = packet;
p.maxlen = len;
p.pos = 0;
if (len<19)return 0;
if (!write_chars(&p, (const unsigned char*)"OpusHead", 8))
return 0;
/* Version is 1 */
ch = 1;
if (!write_chars(&p, &ch, 1))
return 0;
ch = h->channels;
if (!write_chars(&p, &ch, 1))
return 0;
if (!write_uint16(&p, h->preskip))
return 0;
if (!write_uint32(&p, h->input_sample_rate))
return 0;
if (!write_uint16(&p, h->gain))
return 0;
ch = h->channel_mapping;
if (!write_chars(&p, &ch, 1))
return 0;
if (h->channel_mapping != 0)
{
ch = h->nb_streams;
if (!write_chars(&p, &ch, 1))
return 0;
ch = h->nb_coupled;
if (!write_chars(&p, &ch, 1))
return 0;
/* Multi-stream support */
for (i=0;i<h->channels;i++)
{
if (!write_chars(&p, &h->stream_map[i], 1))
return 0;
}
}
return p.pos;
}