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/*
* NAL helper functions for muxers
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdint.h>
#include <string.h>
#include "libavutil/mem.h"
#include "libavutil/error.h"
#include "libavcodec/defs.h"
#include "avio.h"
#include "avio_internal.h"
#include "nal.h"
static const uint8_t *nal_find_startcode_internal(const uint8_t *p, const uint8_t *end)
{
const uint8_t *a = p + 4 - ((intptr_t)p & 3);
for (end -= 3; p < a && p < end; p++) {
if (p[0] == 0 && p[1] == 0 && p[2] == 1)
return p;
}
for (end -= 3; p < end; p += 4) {
uint32_t x = *(const uint32_t*)p;
// if ((x - 0x01000100) & (~x) & 0x80008000) // little endian
// if ((x - 0x00010001) & (~x) & 0x00800080) // big endian
if ((x - 0x01010101) & (~x) & 0x80808080) { // generic
if (p[1] == 0) {
if (p[0] == 0 && p[2] == 1)
return p;
if (p[2] == 0 && p[3] == 1)
return p+1;
}
if (p[3] == 0) {
if (p[2] == 0 && p[4] == 1)
return p+2;
if (p[4] == 0 && p[5] == 1)
return p+3;
}
}
}
for (end += 3; p < end; p++) {
if (p[0] == 0 && p[1] == 0 && p[2] == 1)
return p;
}
return end + 3;
}
const uint8_t *ff_nal_find_startcode(const uint8_t *p, const uint8_t *end){
const uint8_t *out = nal_find_startcode_internal(p, end);
if(p<out && out<end && !out[-1]) out--;
return out;
}
static int nal_parse_units(AVIOContext *pb, NALUList *list,
const uint8_t *buf_in, int size)
{
const uint8_t *p = buf_in;
const uint8_t *end = p + size;
const uint8_t *nal_start, *nal_end;
size = 0;
nal_start = ff_nal_find_startcode(p, end);
for (;;) {
const size_t nalu_limit = SIZE_MAX / sizeof(*list->nalus);
while (nal_start < end && !*(nal_start++));
if (nal_start == end)
break;
nal_end = ff_nal_find_startcode(nal_start, end);
if (pb) {
avio_wb32(pb, nal_end - nal_start);
avio_write(pb, nal_start, nal_end - nal_start);
} else if (list->nb_nalus >= nalu_limit) {
return AVERROR(ERANGE);
} else {
NALU *tmp = av_fast_realloc(list->nalus, &list->nalus_array_size,
(list->nb_nalus + 1) * sizeof(*list->nalus));
if (!tmp)
return AVERROR(ENOMEM);
list->nalus = tmp;
tmp[list->nb_nalus++] = (NALU){ .offset = nal_start - p,
.size = nal_end - nal_start };
}
size += 4 + nal_end - nal_start;
nal_start = nal_end;
}
return size;
}
int ff_nal_parse_units(AVIOContext *pb, const uint8_t *buf_in, int size)
{
return nal_parse_units(pb, NULL, buf_in, size);
}
int ff_nal_units_create_list(NALUList *list, const uint8_t *buf, int size)
{
list->nb_nalus = 0;
return nal_parse_units(NULL, list, buf, size);
}
void ff_nal_units_write_list(const NALUList *list, AVIOContext *pb,
const uint8_t *buf)
{
for (unsigned i = 0; i < list->nb_nalus; i++) {
avio_wb32(pb, list->nalus[i].size);
avio_write(pb, buf + list->nalus[i].offset, list->nalus[i].size);
}
}
int ff_nal_parse_units_buf(const uint8_t *buf_in, uint8_t **buf, int *size)
{
AVIOContext *pb;
int ret = avio_open_dyn_buf(&pb);
if(ret < 0)
return ret;
ff_nal_parse_units(pb, buf_in, *size);
*size = avio_close_dyn_buf(pb, buf);
return 0;
}
const uint8_t *ff_nal_mp4_find_startcode(const uint8_t *start,
const uint8_t *end,
int nal_length_size)
{
unsigned int res = 0;
if (end - start < nal_length_size)
return NULL;
while (nal_length_size--)
res = (res << 8) | *start++;
if (res > end - start)
return NULL;
return start + res;
}
uint8_t *ff_nal_unit_extract_rbsp(const uint8_t *src, uint32_t src_len,
uint32_t *dst_len, int header_len)
{
uint8_t *dst;
uint32_t i, len;
dst = av_malloc(src_len + AV_INPUT_BUFFER_PADDING_SIZE);
if (!dst)
return NULL;
/* NAL unit header */
i = len = 0;
while (i < header_len && i < src_len)
dst[len++] = src[i++];
while (i + 2 < src_len)
if (!src[i] && !src[i + 1] && src[i + 2] == 3) {
dst[len++] = src[i++];
dst[len++] = src[i++];
i++; // remove emulation_prevention_three_byte
} else
dst[len++] = src[i++];
while (i < src_len)
dst[len++] = src[i++];
memset(dst + len, 0, AV_INPUT_BUFFER_PADDING_SIZE);
*dst_len = len;
return dst;
}
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