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![Reinhard Tartler](/assets/img/avatar_default.png)
Because in contrast to the decoder, the parser does not setup low_delay.
The code in parse_nal_units would always end up setting has_b_frames
to "1", except when stream is explicitly marked as low delay.
Since the parser itself would create 'extradata', simply reopening
the parser would cause this.
This happens for instance in estimate_timings_from_pts(), which causes the
parser to be reopened on the same stream.
This fixes Libav #22 and FFmpeg (trac) #360
CC: libav-stable@libav.org
Based on a patch by Reimar Döffinger <Reimar.Doeffinger@gmx.de>
(commit 31ac0ac29b
)
Comments and description adapted by Reinhard Tartler.
Signed-off-by: Reinhard Tartler <siretart@tauware.de>
352 lines
11 KiB
C
352 lines
11 KiB
C
/*
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* H.26L/H.264/AVC/JVT/14496-10/... parser
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* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
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*
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* This file is part of Libav.
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*
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* Libav 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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* Libav 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 Libav; 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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/**
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* @file
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* H.264 / AVC / MPEG4 part10 parser.
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* @author Michael Niedermayer <michaelni@gmx.at>
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*/
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#include "parser.h"
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#include "h264data.h"
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#include "golomb.h"
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#include <assert.h>
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static int ff_h264_find_frame_end(H264Context *h, const uint8_t *buf, int buf_size)
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{
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int i;
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uint32_t state;
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ParseContext *pc = &(h->s.parse_context);
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//printf("first %02X%02X%02X%02X\n", buf[0], buf[1],buf[2],buf[3]);
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// mb_addr= pc->mb_addr - 1;
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state= pc->state;
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if(state>13)
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state= 7;
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for(i=0; i<buf_size; i++){
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if(state==7){
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#if HAVE_FAST_UNALIGNED
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/* we check i<buf_size instead of i+3/7 because its simpler
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* and there should be FF_INPUT_BUFFER_PADDING_SIZE bytes at the end
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*/
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# if HAVE_FAST_64BIT
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while(i<buf_size && !((~*(const uint64_t*)(buf+i) & (*(const uint64_t*)(buf+i) - 0x0101010101010101ULL)) & 0x8080808080808080ULL))
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i+=8;
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# else
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while(i<buf_size && !((~*(const uint32_t*)(buf+i) & (*(const uint32_t*)(buf+i) - 0x01010101U)) & 0x80808080U))
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i+=4;
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# endif
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#endif
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for(; i<buf_size; i++){
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if(!buf[i]){
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state=2;
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break;
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}
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}
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}else if(state<=2){
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if(buf[i]==1) state^= 5; //2->7, 1->4, 0->5
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else if(buf[i]) state = 7;
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else state>>=1; //2->1, 1->0, 0->0
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}else if(state<=5){
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int v= buf[i] & 0x1F;
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if(v==6 || v==7 || v==8 || v==9){
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if(pc->frame_start_found){
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i++;
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goto found;
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}
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}else if(v==1 || v==2 || v==5){
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if(pc->frame_start_found){
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state+=8;
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continue;
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}else
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pc->frame_start_found = 1;
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}
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state= 7;
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}else{
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if(buf[i] & 0x80)
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goto found;
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state= 7;
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}
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}
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pc->state= state;
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return END_NOT_FOUND;
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found:
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pc->state=7;
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pc->frame_start_found= 0;
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return i-(state&5);
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}
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/**
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* Parse NAL units of found picture and decode some basic information.
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*
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* @param s parser context.
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* @param avctx codec context.
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* @param buf buffer with field/frame data.
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* @param buf_size size of the buffer.
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*/
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static inline int parse_nal_units(AVCodecParserContext *s,
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AVCodecContext *avctx,
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const uint8_t *buf, int buf_size)
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{
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H264Context *h = s->priv_data;
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const uint8_t *buf_end = buf + buf_size;
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unsigned int pps_id;
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unsigned int slice_type;
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int state = -1;
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const uint8_t *ptr;
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/* set some sane default values */
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s->pict_type = AV_PICTURE_TYPE_I;
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s->key_frame = 0;
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h->s.avctx= avctx;
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h->sei_recovery_frame_cnt = -1;
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h->sei_dpb_output_delay = 0;
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h->sei_cpb_removal_delay = -1;
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h->sei_buffering_period_present = 0;
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if (!buf_size)
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return 0;
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for(;;) {
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int src_length, dst_length, consumed;
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buf = avpriv_mpv_find_start_code(buf, buf_end, &state);
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if(buf >= buf_end)
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break;
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--buf;
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src_length = buf_end - buf;
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switch (state & 0x1f) {
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case NAL_SLICE:
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case NAL_IDR_SLICE:
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// Do not walk the whole buffer just to decode slice header
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if (src_length > 20)
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src_length = 20;
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break;
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}
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ptr= ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
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if (ptr==NULL || dst_length < 0)
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break;
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init_get_bits(&h->s.gb, ptr, 8*dst_length);
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switch(h->nal_unit_type) {
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case NAL_SPS:
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ff_h264_decode_seq_parameter_set(h);
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break;
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case NAL_PPS:
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ff_h264_decode_picture_parameter_set(h, h->s.gb.size_in_bits);
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break;
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case NAL_SEI:
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ff_h264_decode_sei(h);
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break;
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case NAL_IDR_SLICE:
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s->key_frame = 1;
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/* fall through */
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case NAL_SLICE:
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get_ue_golomb(&h->s.gb); // skip first_mb_in_slice
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slice_type = get_ue_golomb_31(&h->s.gb);
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s->pict_type = golomb_to_pict_type[slice_type % 5];
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if (h->sei_recovery_frame_cnt >= 0) {
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/* key frame, since recovery_frame_cnt is set */
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s->key_frame = 1;
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}
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pps_id= get_ue_golomb(&h->s.gb);
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if(pps_id>=MAX_PPS_COUNT) {
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av_log(h->s.avctx, AV_LOG_ERROR, "pps_id out of range\n");
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return -1;
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}
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if(!h->pps_buffers[pps_id]) {
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av_log(h->s.avctx, AV_LOG_ERROR, "non-existing PPS referenced\n");
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return -1;
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}
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h->pps= *h->pps_buffers[pps_id];
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if(!h->sps_buffers[h->pps.sps_id]) {
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av_log(h->s.avctx, AV_LOG_ERROR, "non-existing SPS referenced\n");
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return -1;
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}
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h->sps = *h->sps_buffers[h->pps.sps_id];
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h->frame_num = get_bits(&h->s.gb, h->sps.log2_max_frame_num);
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avctx->profile = ff_h264_get_profile(&h->sps);
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avctx->level = h->sps.level_idc;
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if(h->sps.frame_mbs_only_flag){
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h->s.picture_structure= PICT_FRAME;
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}else{
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if(get_bits1(&h->s.gb)) { //field_pic_flag
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h->s.picture_structure= PICT_TOP_FIELD + get_bits1(&h->s.gb); //bottom_field_flag
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} else {
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h->s.picture_structure= PICT_FRAME;
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}
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}
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if(h->sps.pic_struct_present_flag) {
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switch (h->sei_pic_struct) {
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case SEI_PIC_STRUCT_TOP_FIELD:
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case SEI_PIC_STRUCT_BOTTOM_FIELD:
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s->repeat_pict = 0;
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break;
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case SEI_PIC_STRUCT_FRAME:
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case SEI_PIC_STRUCT_TOP_BOTTOM:
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case SEI_PIC_STRUCT_BOTTOM_TOP:
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s->repeat_pict = 1;
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break;
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case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
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case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
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s->repeat_pict = 2;
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break;
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case SEI_PIC_STRUCT_FRAME_DOUBLING:
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s->repeat_pict = 3;
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break;
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case SEI_PIC_STRUCT_FRAME_TRIPLING:
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s->repeat_pict = 5;
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break;
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default:
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s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
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break;
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}
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} else {
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s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
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}
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return 0; /* no need to evaluate the rest */
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}
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buf += consumed;
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}
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/* didn't find a picture! */
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av_log(h->s.avctx, AV_LOG_ERROR, "missing picture in access unit\n");
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return -1;
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}
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static int h264_parse(AVCodecParserContext *s,
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AVCodecContext *avctx,
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const uint8_t **poutbuf, int *poutbuf_size,
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const uint8_t *buf, int buf_size)
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{
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H264Context *h = s->priv_data;
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ParseContext *pc = &h->s.parse_context;
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int next;
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if (!h->got_first) {
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h->got_first = 1;
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if (avctx->extradata_size) {
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h->s.avctx = avctx;
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// must be done like in the decoder.
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// otherwise opening the parser, creating extradata,
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// and then closing and opening again
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// will cause has_b_frames to be always set.
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// NB: estimate_timings_from_pts behaves exactly like this.
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if (!avctx->has_b_frames)
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h->s.low_delay = 1;
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ff_h264_decode_extradata(h);
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}
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}
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if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
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next= buf_size;
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}else{
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next= ff_h264_find_frame_end(h, buf, buf_size);
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if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
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*poutbuf = NULL;
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*poutbuf_size = 0;
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return buf_size;
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}
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if(next<0 && next != END_NOT_FOUND){
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assert(pc->last_index + next >= 0 );
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ff_h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); //update state
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}
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}
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parse_nal_units(s, avctx, buf, buf_size);
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if (h->sei_cpb_removal_delay >= 0) {
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s->dts_sync_point = h->sei_buffering_period_present;
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s->dts_ref_dts_delta = h->sei_cpb_removal_delay;
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s->pts_dts_delta = h->sei_dpb_output_delay;
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} else {
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s->dts_sync_point = INT_MIN;
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s->dts_ref_dts_delta = INT_MIN;
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s->pts_dts_delta = INT_MIN;
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}
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if (s->flags & PARSER_FLAG_ONCE) {
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s->flags &= PARSER_FLAG_COMPLETE_FRAMES;
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}
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*poutbuf = buf;
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*poutbuf_size = buf_size;
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return next;
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}
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static int h264_split(AVCodecContext *avctx,
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const uint8_t *buf, int buf_size)
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{
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int i;
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uint32_t state = -1;
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int has_sps= 0;
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for(i=0; i<=buf_size; i++){
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if((state&0xFFFFFF1F) == 0x107)
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has_sps=1;
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/* if((state&0xFFFFFF1F) == 0x101 || (state&0xFFFFFF1F) == 0x102 || (state&0xFFFFFF1F) == 0x105){
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}*/
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if((state&0xFFFFFF00) == 0x100 && (state&0xFFFFFF1F) != 0x107 && (state&0xFFFFFF1F) != 0x108 && (state&0xFFFFFF1F) != 0x109){
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if(has_sps){
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while(i>4 && buf[i-5]==0) i--;
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return i-4;
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}
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}
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if (i<buf_size)
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state= (state<<8) | buf[i];
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}
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return 0;
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}
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static void close(AVCodecParserContext *s)
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{
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H264Context *h = s->priv_data;
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ParseContext *pc = &h->s.parse_context;
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av_free(pc->buffer);
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ff_h264_free_context(h);
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}
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static int init(AVCodecParserContext *s)
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{
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H264Context *h = s->priv_data;
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h->thread_context[0] = h;
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h->s.slice_context_count = 1;
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return 0;
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}
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AVCodecParser ff_h264_parser = {
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.codec_ids = { CODEC_ID_H264 },
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.priv_data_size = sizeof(H264Context),
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.parser_init = init,
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.parser_parse = h264_parse,
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.parser_close = close,
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.split = h264_split,
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};
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