ref: 875f8dbd56e303985a69ab9b4e0c7cf840741afa
dir: /src/opus_decoder.c/
/* Copyright (c) 2010 Xiph.Org Foundation, Skype Limited
Written by Jean-Marc Valin and Koen Vos */
/*
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 <stdarg.h>
#include "celt.h"
#include "opus.h"
#include "entdec.h"
#include "modes.h"
#include "silk_API.h"
#include "stack_alloc.h"
#include "float_cast.h"
#include "opus_private.h"
#include "os_support.h"
struct OpusDecoder {
int celt_dec_offset;
int silk_dec_offset;
int channels;
int Fs; /** Sampling rate (at the API level) */
/* Everything beyond this point gets cleared on a reset */
#define OPUS_DECODER_RESET_START stream_channels
int stream_channels;
int bandwidth;
int mode;
int prev_mode;
int frame_size;
int prev_redundancy;
int rangeFinal;
};
#ifdef FIXED_POINT
static inline opus_int16 SAT16(opus_int32 x) {
return x > 32767 ? 32767 : x < -32768 ? -32768 : (opus_int16)x;
};
#endif
int opus_decoder_get_size(int channels)
{
int silkDecSizeBytes, celtDecSizeBytes;
int ret;
ret = silk_Get_Decoder_Size( &silkDecSizeBytes );
if(ret)
return 0;
silkDecSizeBytes = align(silkDecSizeBytes);
celtDecSizeBytes = celt_decoder_get_size(channels);
return align(sizeof(OpusDecoder))+silkDecSizeBytes+celtDecSizeBytes;
}
int opus_decoder_init(OpusDecoder *st, int Fs, int channels)
{
void *silk_dec;
CELTDecoder *celt_dec;
int ret, silkDecSizeBytes;
if (channels<1 || channels > 2)
return OPUS_BAD_ARG;
OPUS_CLEAR((char*)st, opus_decoder_get_size(channels));
/* Initialize SILK encoder */
ret = silk_Get_Decoder_Size( &silkDecSizeBytes );
if( ret ) {
return OPUS_INTERNAL_ERROR;
}
silkDecSizeBytes = align(silkDecSizeBytes);
st->silk_dec_offset = align(sizeof(OpusDecoder));
st->celt_dec_offset = st->silk_dec_offset+silkDecSizeBytes;
silk_dec = (char*)st+st->silk_dec_offset;
celt_dec = (CELTDecoder*)((char*)st+st->celt_dec_offset);
st->stream_channels = st->channels = channels;
st->Fs = Fs;
/* Reset decoder */
ret = silk_InitDecoder( silk_dec );
if( ret ) {
goto failure;
}
/* Initialize CELT decoder */
ret = celt_decoder_init(celt_dec, Fs, channels);
if (ret != CELT_OK)
goto failure;
celt_decoder_ctl(celt_dec, CELT_SET_SIGNALLING(0));
st->prev_mode = 0;
st->frame_size = Fs/400;
return OPUS_OK;
failure:
opus_free(st);
return OPUS_INTERNAL_ERROR;
}
OpusDecoder *opus_decoder_create(int Fs, int channels, int *error)
{
int ret;
OpusDecoder *st = (OpusDecoder *)opus_alloc(opus_decoder_get_size(channels));
if (st == NULL)
{
if (error)
*error = OPUS_ALLOC_FAIL;
return NULL;
}
ret = opus_decoder_init(st, Fs, channels);
if (ret != OPUS_OK)
{
opus_free(st);
st = NULL;
}
return st;
}
static void smooth_fade(const opus_val16 *in1, const opus_val16 *in2, opus_val16 *out,
int overlap, int channels, const opus_val16 *window, int Fs)
{
int i, c;
int inc = 48000/Fs;
for (c=0;c<channels;c++)
{
for (i=0;i<overlap;i++)
{
opus_val16 w = MULT16_16_Q15(window[i*inc], window[i*inc]);
out[i*channels+c] = SHR32(MAC16_16(MULT16_16(w,in2[i*channels+c]),
Q15ONE-w, in1[i*channels+c]), 15);
}
}
}
static int opus_packet_get_mode(const unsigned char *data)
{
int mode;
if (data[0]&0x80)
{
mode = MODE_CELT_ONLY;
} else if ((data[0]&0x60) == 0x60)
{
mode = MODE_HYBRID;
} else {
mode = MODE_SILK_ONLY;
}
return mode;
}
static int opus_decode_frame(OpusDecoder *st, const unsigned char *data,
int len, opus_val16 *pcm, int frame_size, int decode_fec)
{
void *silk_dec;
CELTDecoder *celt_dec;
int i, silk_ret=0, celt_ret=0;
ec_dec dec;
silk_DecControlStruct DecControl;
opus_int32 silk_frame_size;
VARDECL(opus_int16, pcm_silk);
VARDECL(opus_val16, pcm_transition);
VARDECL(opus_val16, redundant_audio);
int audiosize;
int mode;
int transition=0;
int start_band;
int redundancy=0;
int redundancy_bytes = 0;
int celt_to_silk=0;
int c;
int F2_5, F5, F10, F20;
const opus_val16 *window;
opus_uint32 redundant_rng = 0;
ALLOC_STACK;
silk_dec = (char*)st+st->silk_dec_offset;
celt_dec = (CELTDecoder*)((char*)st+st->celt_dec_offset);
F20 = st->Fs/50;
F10 = F20>>1;
F5 = F10>>1;
F2_5 = F5>>1;
if (frame_size < F2_5)
return OPUS_BUFFER_TOO_SMALL;
/* Payloads of 1 (2 including ToC) or 0 trigger the PLC/DTX */
if (len<=1)
{
data = NULL;
/* In that case, don't conceal more than what the ToC says */
frame_size = IMIN(frame_size, st->frame_size);
}
if (data != NULL)
{
audiosize = st->frame_size;
mode = st->mode;
ec_dec_init(&dec,(unsigned char*)data,len);
} else {
audiosize = frame_size;
if (st->prev_mode == 0)
{
/* If we haven't got any packet yet, all we can do is return zeros */
for (i=0;i<audiosize*st->channels;i++)
pcm[i] = 0;
RESTORE_STACK;
return audiosize;
} else {
mode = st->prev_mode;
}
}
ALLOC(pcm_transition, F5*st->channels, opus_val16);
if (data!=NULL && !st->prev_redundancy && mode != st->prev_mode && st->prev_mode > 0
&& !(mode == MODE_SILK_ONLY && st->prev_mode == MODE_HYBRID)
&& !(mode == MODE_HYBRID && st->prev_mode == MODE_SILK_ONLY))
{
transition = 1;
if (mode == MODE_CELT_ONLY)
opus_decode_frame(st, NULL, 0, pcm_transition, IMIN(F5, audiosize), 0);
}
if (audiosize > frame_size)
{
/*fprintf(stderr, "PCM buffer too small: %d vs %d (mode = %d)\n", audiosize, frame_size, mode);*/
RESTORE_STACK;
return OPUS_BAD_ARG;
} else {
frame_size = audiosize;
}
ALLOC(pcm_silk, frame_size*st->channels, opus_int16);
ALLOC(redundant_audio, F5*st->channels, opus_val16);
/* SILK processing */
if (mode != MODE_CELT_ONLY)
{
int lost_flag, decoded_samples;
opus_int16 *pcm_ptr = pcm_silk;
if (st->prev_mode==MODE_CELT_ONLY)
silk_InitDecoder( silk_dec );
DecControl.API_sampleRate = st->Fs;
DecControl.nChannelsAPI = st->channels;
DecControl.nChannelsInternal = st->stream_channels;
DecControl.payloadSize_ms = 1000 * audiosize / st->Fs;
if( mode == MODE_SILK_ONLY ) {
if( st->bandwidth == OPUS_BANDWIDTH_NARROWBAND ) {
DecControl.internalSampleRate = 8000;
} else if( st->bandwidth == OPUS_BANDWIDTH_MEDIUMBAND ) {
DecControl.internalSampleRate = 12000;
} else if( st->bandwidth == OPUS_BANDWIDTH_WIDEBAND ) {
DecControl.internalSampleRate = 16000;
} else {
DecControl.internalSampleRate = 16000;
SKP_assert( 0 );
}
} else {
/* Hybrid mode */
DecControl.internalSampleRate = 16000;
}
lost_flag = data == NULL ? 1 : 2 * decode_fec;
decoded_samples = 0;
do {
/* Call SILK decoder */
int first_frame = decoded_samples == 0;
silk_ret = silk_Decode( silk_dec, &DecControl,
lost_flag, first_frame, &dec, pcm_ptr, &silk_frame_size );
if( silk_ret ) {
if (lost_flag) {
/* PLC failure should not be fatal */
silk_frame_size = frame_size;
for (i=0;i<frame_size*st->channels;i++)
pcm_ptr[i] = 0;
} else {
RESTORE_STACK;
return OPUS_CORRUPTED_DATA;
}
}
pcm_ptr += silk_frame_size * st->channels;
decoded_samples += silk_frame_size;
} while( decoded_samples < frame_size );
}
start_band = 0;
if (mode != MODE_CELT_ONLY && data != NULL)
{
/* Check if we have a redundant 0-8 kHz band */
redundancy = ec_dec_bit_logp(&dec, 12);
if (redundancy)
{
celt_to_silk = ec_dec_bit_logp(&dec, 1);
if (mode == MODE_HYBRID)
redundancy_bytes = 2 + ec_dec_uint(&dec, 256);
else {
redundancy_bytes = len - ((ec_tell(&dec)+7)>>3);
/* Can only happen on an invalid packet */
if (redundancy_bytes<0)
{
redundancy_bytes = 0;
redundancy = 0;
}
}
len -= redundancy_bytes;
if (len<0) {
RESTORE_STACK;
return OPUS_CORRUPTED_DATA;
}
/* Shrink decoder because of raw bits */
dec.storage -= redundancy_bytes;
}
}
if (mode != MODE_CELT_ONLY)
start_band = 17;
{
int endband=21;
switch(st->bandwidth)
{
case OPUS_BANDWIDTH_NARROWBAND:
endband = 13;
break;
case OPUS_BANDWIDTH_MEDIUMBAND:
case OPUS_BANDWIDTH_WIDEBAND:
endband = 17;
break;
case OPUS_BANDWIDTH_SUPERWIDEBAND:
endband = 19;
break;
case OPUS_BANDWIDTH_FULLBAND:
endband = 21;
break;
}
celt_decoder_ctl(celt_dec, CELT_SET_END_BAND(endband));
celt_decoder_ctl(celt_dec, CELT_SET_CHANNELS(st->stream_channels));
}
if (redundancy)
transition = 0;
if (transition && mode != MODE_CELT_ONLY)
opus_decode_frame(st, NULL, 0, pcm_transition, IMIN(F5, audiosize), 0);
/* 5 ms redundant frame for CELT->SILK*/
if (redundancy && celt_to_silk)
{
celt_decoder_ctl(celt_dec, CELT_SET_START_BAND(0));
celt_decode_with_ec(celt_dec, data+len, redundancy_bytes, redundant_audio, F5, NULL);
celt_decoder_ctl(celt_dec, CELT_GET_RANGE(&redundant_rng));
celt_decoder_ctl(celt_dec, CELT_RESET_STATE);
}
/* MUST be after PLC */
celt_decoder_ctl(celt_dec, CELT_SET_START_BAND(start_band));
if (transition)
celt_decoder_ctl(celt_dec, CELT_RESET_STATE);
if (mode != MODE_SILK_ONLY)
{
int celt_frame_size = IMIN(F20, frame_size);
/* Decode CELT */
celt_ret = celt_decode_with_ec(celt_dec, decode_fec?NULL:data, len, pcm, celt_frame_size, &dec);
} else {
for (i=0;i<frame_size*st->channels;i++)
pcm[i] = 0;
}
if (mode != MODE_CELT_ONLY)
{
#ifdef FIXED_POINT
for (i=0;i<frame_size*st->channels;i++)
pcm[i] = SAT16(pcm[i] + pcm_silk[i]);
#else
for (i=0;i<frame_size*st->channels;i++)
pcm[i] = pcm[i] + (1./32768.)*pcm_silk[i];
#endif
}
{
const CELTMode *celt_mode;
celt_decoder_ctl(celt_dec, CELT_GET_MODE(&celt_mode));
window = celt_mode->window;
}
/* 5 ms redundant frame for SILK->CELT */
if (redundancy && !celt_to_silk)
{
celt_decoder_ctl(celt_dec, CELT_RESET_STATE);
celt_decoder_ctl(celt_dec, CELT_SET_START_BAND(0));
celt_decode_with_ec(celt_dec, data+len, redundancy_bytes, redundant_audio, F5, NULL);
celt_decoder_ctl(celt_dec, CELT_GET_RANGE(&redundant_rng));
smooth_fade(pcm+st->channels*(frame_size-F2_5), redundant_audio+st->channels*F2_5,
pcm+st->channels*(frame_size-F2_5), F2_5, st->channels, window, st->Fs);
}
if (redundancy && celt_to_silk)
{
for (c=0;c<st->channels;c++)
{
for (i=0;i<F2_5;i++)
pcm[st->channels*i+c] = redundant_audio[st->channels*i+c];
}
smooth_fade(redundant_audio+st->channels*F2_5, pcm+st->channels*F2_5,
pcm+st->channels*F2_5, F2_5, st->channels, window, st->Fs);
}
if (transition)
{
for (i=0;i<st->channels*F2_5;i++)
pcm[i] = pcm_transition[i];
if (audiosize >= F5)
smooth_fade(pcm_transition+st->channels*F2_5, pcm+st->channels*F2_5,
pcm+st->channels*F2_5, F2_5,
st->channels, window, st->Fs);
}
if (len <= 1)
st->rangeFinal = 0;
else
st->rangeFinal = dec.rng ^ redundant_rng;
st->prev_mode = mode;
st->prev_redundancy = redundancy;
RESTORE_STACK;
return celt_ret<0 ? celt_ret : audiosize;
}
static int parse_size(const unsigned char *data, int len, short *size)
{
if (len<1)
{
*size = -1;
return -1;
} else if (data[0]<252)
{
*size = data[0];
return 1;
} else if (len<2)
{
*size = -1;
return -1;
} else {
*size = 4*data[1] + data[0];
return 2;
}
}
static int opus_packet_parse_impl(const unsigned char *data, int len,
int self_delimited, unsigned char *out_toc,
const unsigned char *frames[48], short size[48], int *payload_offset)
{
int i, bytes;
int count;
int cbr;
unsigned char ch, toc;
int framesize;
int last_size;
const unsigned char *data0 = data;
if (size==NULL)
return OPUS_BAD_ARG;
framesize = opus_packet_get_samples_per_frame(data, 48000);
cbr = 0;
toc = *data++;
len--;
last_size = len;
switch (toc&0x3)
{
/* One frame */
case 0:
count=1;
break;
/* Two CBR frames */
case 1:
count=2;
cbr = 1;
if (!self_delimited)
{
if (len&0x1)
return OPUS_CORRUPTED_DATA;
size[0] = last_size = len/2;
}
break;
/* Two VBR frames */
case 2:
count = 2;
bytes = parse_size(data, len, size);
len -= bytes;
if (size[0]<0 || size[0] > len)
return OPUS_CORRUPTED_DATA;
data += bytes;
last_size = len-size[0];
break;
/* Multiple CBR/VBR frames (from 0 to 120 ms) */
case 3:
if (len<1)
return OPUS_CORRUPTED_DATA;
/* Number of frames encoded in bits 0 to 5 */
ch = *data++;
count = ch&0x3F;
if (count <= 0 || framesize*count > 5760)
return OPUS_CORRUPTED_DATA;
len--;
/* Padding flag is bit 6 */
if (ch&0x40)
{
int padding=0;
int p;
do {
if (len<=0)
return OPUS_CORRUPTED_DATA;
p = *data++;
len--;
padding += p==255 ? 254: p;
} while (p==255);
len -= padding;
}
if (len<0)
return OPUS_CORRUPTED_DATA;
/* VBR flag is bit 7 */
cbr = !(ch&0x80);
if (cbr)
{
/* VBR case */
last_size = len;
for (i=0;i<count-1;i++)
{
bytes = parse_size(data, len, size+i);
len -= bytes;
if (size[i]<0 || size[i] > len)
return OPUS_CORRUPTED_DATA;
data += bytes;
last_size -= bytes+size[i];
}
if (last_size<0)
return OPUS_CORRUPTED_DATA;
} else if (!self_delimited)
{
/* CBR case */
last_size = len/count;
if (last_size*count!=len)
return OPUS_CORRUPTED_DATA;
for (i=0;i<count-1;i++)
size[i] = last_size;
}
break;
}
/* Self-delimited framing has an extra size for the last frame. */
if (self_delimited)
{
bytes = parse_size(data, len, size+count-1);
len -= bytes;
if (size[count-1]<0 || size[count-1] > len)
return OPUS_CORRUPTED_DATA;
data += bytes;
/* For CBR packets, apply the size to all the frames. */
if (cbr)
{
if (size[count-1]*count > len)
return OPUS_CORRUPTED_DATA;
for (i=0;i<count-1;i++)
size[i] = size[count-1];
} else if(size[count-1] > last_size)
return OPUS_CORRUPTED_DATA;
} else
{
/* Because it's not encoded explicitly, it's possible the size of the
last packet (or all the packets, for the CBR case) is larger than
1275.
Reject them here.*/
if (last_size > 1275)
return OPUS_CORRUPTED_DATA;
size[count-1] = last_size;
}
if (frames)
{
for (i=0;i<count;i++)
{
frames[i] = data;
data += size[i];
}
}
if (out_toc)
*out_toc = toc;
if (payload_offset)
*payload_offset = data-data0;
return count;
}
int opus_packet_parse(const unsigned char *data, int len,
unsigned char *out_toc, const unsigned char *frames[48],
short size[48], int *payload_offset)
{
return opus_packet_parse_impl(data, len, 0,
out_toc, frames, size, payload_offset);
}
int opus_decode_native(OpusDecoder *st, const unsigned char *data,
int len, opus_val16 *pcm, int frame_size, int decode_fec, int self_delimited, int *packet_offset)
{
int i, nb_samples;
int count, offset;
unsigned char toc;
int tot_offset;
/* 48 x 2.5 ms = 120 ms */
short size[48];
if (len==0 || data==NULL)
return opus_decode_frame(st, NULL, 0, pcm, frame_size, 0);
else if (len<0)
return OPUS_BAD_ARG;
tot_offset = 0;
st->mode = opus_packet_get_mode(data);
st->bandwidth = opus_packet_get_bandwidth(data);
st->frame_size = opus_packet_get_samples_per_frame(data, st->Fs);
st->stream_channels = opus_packet_get_nb_channels(data);
count = opus_packet_parse_impl(data, len, 0, &toc, NULL, size, &offset);
if (count < 0)
return count;
data += offset;
tot_offset += offset;
if (count*st->frame_size > frame_size)
return OPUS_BAD_ARG;
nb_samples=0;
for (i=0;i<count;i++)
{
int ret;
ret = opus_decode_frame(st, data, size[i], pcm, frame_size-nb_samples, decode_fec);
if (ret<0)
return ret;
data += size[i];
tot_offset += size[i];
pcm += ret*st->channels;
nb_samples += ret;
}
if (packet_offset != NULL)
*packet_offset = tot_offset;
return nb_samples;
}
#ifdef FIXED_POINT
int opus_decode(OpusDecoder *st, const unsigned char *data,
int len, opus_val16 *pcm, int frame_size, int decode_fec)
{
return opus_decode_native(st, data, len, pcm, frame_size, decode_fec, 0, NULL);
}
#ifndef DISABLE_FLOAT_API
int opus_decode_float(OpusDecoder *st, const unsigned char *data,
int len, float *pcm, int frame_size, int decode_fec)
{
VARDECL(opus_int16, out);
int ret, i;
ALLOC_STACK;
ALLOC(out, frame_size*st->channels, opus_int16);
ret = opus_decode_native(st, data, len, out, frame_size, decode_fec, 0, NULL);
if (ret > 0)
{
for (i=0;i<ret*st->channels;i++)
pcm[i] = (1./32768.)*(out[i]);
}
RESTORE_STACK;
return ret;
}
#endif
#else
int opus_decode(OpusDecoder *st, const unsigned char *data,
int len, opus_int16 *pcm, int frame_size, int decode_fec)
{
VARDECL(float, out);
int ret, i;
ALLOC_STACK;
ALLOC(out, frame_size*st->channels, float);
ret = opus_decode_native(st, data, len, out, frame_size, decode_fec, 0, NULL);
if (ret > 0)
{
for (i=0;i<ret*st->channels;i++)
pcm[i] = FLOAT2INT16(out[i]);
}
RESTORE_STACK;
return ret;
}
int opus_decode_float(OpusDecoder *st, const unsigned char *data,
int len, opus_val16 *pcm, int frame_size, int decode_fec)
{
return opus_decode_native(st, data, len, pcm, frame_size, decode_fec, 0, NULL);
}
#endif
int opus_decoder_ctl(OpusDecoder *st, int request, ...)
{
int ret = OPUS_OK;
va_list ap;
va_start(ap, request);
switch (request)
{
case OPUS_GET_BANDWIDTH_REQUEST:
{
opus_int32 *value = va_arg(ap, opus_int32*);
*value = st->bandwidth;
}
break;
case OPUS_GET_FINAL_RANGE_REQUEST:
{
opus_uint32 *value = va_arg(ap, opus_uint32*);
*value = st->rangeFinal;
}
break;
case OPUS_RESET_STATE:
{
void *silk_dec;
CELTDecoder *celt_dec;
silk_dec = (char*)st+st->silk_dec_offset;
celt_dec = (CELTDecoder*)((char*)st+st->celt_dec_offset);
OPUS_CLEAR((char*)&st->OPUS_DECODER_RESET_START,
opus_decoder_get_size(st->channels)-
((char*)&st->OPUS_DECODER_RESET_START - (char*)st));
celt_decoder_ctl(celt_dec, CELT_RESET_STATE);
silk_InitDecoder( silk_dec );
st->stream_channels = st->channels;
st->frame_size = st->Fs/400;
}
break;
default:
/*fprintf(stderr, "unknown opus_decoder_ctl() request: %d", request);*/
ret = OPUS_BAD_ARG;
break;
}
va_end(ap);
return ret;
}
void opus_decoder_destroy(OpusDecoder *st)
{
opus_free(st);
}
int opus_packet_get_bandwidth(const unsigned char *data)
{
int bandwidth;
if (data[0]&0x80)
{
bandwidth = OPUS_BANDWIDTH_MEDIUMBAND + ((data[0]>>5)&0x3);
if (bandwidth == OPUS_BANDWIDTH_MEDIUMBAND)
bandwidth = OPUS_BANDWIDTH_NARROWBAND;
} else if ((data[0]&0x60) == 0x60)
{
bandwidth = (data[0]&0x10) ? OPUS_BANDWIDTH_FULLBAND : OPUS_BANDWIDTH_SUPERWIDEBAND;
} else {
bandwidth = OPUS_BANDWIDTH_NARROWBAND + ((data[0]>>5)&0x3);
}
return bandwidth;
}
int opus_packet_get_samples_per_frame(const unsigned char *data, int Fs)
{
int audiosize;
if (data[0]&0x80)
{
audiosize = ((data[0]>>3)&0x3);
audiosize = (Fs<<audiosize)/400;
} else if ((data[0]&0x60) == 0x60)
{
audiosize = (data[0]&0x08) ? Fs/50 : Fs/100;
} else {
audiosize = ((data[0]>>3)&0x3);
if (audiosize == 3)
audiosize = Fs*60/1000;
else
audiosize = (Fs<<audiosize)/100;
}
return audiosize;
}
int opus_packet_get_nb_channels(const unsigned char *data)
{
return (data[0]&0x4) ? 2 : 1;
}
int opus_packet_get_nb_frames(const unsigned char packet[], int len)
{
int count;
if (len<1)
return OPUS_BAD_ARG;
count = packet[0]&0x3;
if (count==0)
return 1;
else if (count!=3)
return 2;
else if (len<2)
return OPUS_CORRUPTED_DATA;
else
return packet[1]&0x3F;
}
int opus_decoder_get_nb_samples(const OpusDecoder *dec, const unsigned char packet[], int len)
{
int samples;
int count = opus_packet_get_nb_frames(packet, len);
samples = count*opus_packet_get_samples_per_frame(packet, dec->Fs);
/* Can't have more than 120 ms */
if (samples*25 > dec->Fs*3)
return OPUS_CORRUPTED_DATA;
else
return samples;
}