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