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ffmpeg/libavcodec/h264_parser.c

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/*
* H.26L/H.264/AVC/JVT/14496-10/... parser
* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
*
* 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
*/
/**
* @file
* H.264 / AVC / MPEG4 part10 parser.
* @author Michael Niedermayer <michaelni@gmx.at>
*/
#define UNCHECKED_BITSTREAM_READER 1
#include "parser.h"
#include "h264data.h"
#include "golomb.h"
static int ff_h264_find_frame_end(H264Context *h, const uint8_t *buf, int buf_size)
{
int i, j;
uint32_t state;
ParseContext *pc = &(h->s.parse_context);
int next_avc= h->is_avc ? 0 : buf_size;
//printf("first %02X%02X%02X%02X\n", buf[0], buf[1],buf[2],buf[3]);
// mb_addr= pc->mb_addr - 1;
state= pc->state;
if(state>13)
state= 7;
if(h->is_avc && !h->nal_length_size)
av_log(h->s.avctx, AV_LOG_ERROR, "AVC-parser: nal length size invalid\n");
for(i=0; i<buf_size; i++){
if(i >= next_avc) {
int nalsize = 0;
i = next_avc;
for(j = 0; j < h->nal_length_size; j++)
nalsize = (nalsize << 8) | buf[i++];
if(nalsize <= 0 || nalsize > buf_size - i){
av_log(h->s.avctx, AV_LOG_ERROR, "AVC-parser: nal size %d remaining %d\n", nalsize, buf_size - i);
return buf_size;
}
next_avc= i + nalsize;
state= 5;
}
if(state==7){
#if HAVE_FAST_UNALIGNED
/* we check i<buf_size instead of i+3/7 because its simpler
* and there should be FF_INPUT_BUFFER_PADDING_SIZE bytes at the end
*/
# if HAVE_FAST_64BIT
while(i<next_avc && !((~*(const uint64_t*)(buf+i) & (*(const uint64_t*)(buf+i) - 0x0101010101010101ULL)) & 0x8080808080808080ULL))
i+=8;
# else
while(i<next_avc && !((~*(const uint32_t*)(buf+i) & (*(const uint32_t*)(buf+i) - 0x01010101U)) & 0x80808080U))
i+=4;
# endif
#endif
for(; i<next_avc; i++){
if(!buf[i]){
state=2;
break;
}
}
}else if(state<=2){
if(buf[i]==1) state^= 5; //2->7, 1->4, 0->5
else if(buf[i]) state = 7;
else state>>=1; //2->1, 1->0, 0->0
}else if(state<=5){
int v= buf[i] & 0x1F;
if(v==6 || v==7 || v==8 || v==9){
if(pc->frame_start_found){
i++;
goto found;
}
}else if(v==1 || v==2 || v==5){
state+=8;
continue;
}
state= 7;
}else{
h->parse_history[h->parse_history_count++]= buf[i];
if(h->parse_history_count>3){
unsigned int mb, last_mb= h->parse_last_mb;
GetBitContext gb;
init_get_bits(&gb, h->parse_history, 8*h->parse_history_count);
h->parse_history_count=0;
mb= get_ue_golomb_long(&gb);
last_mb= h->parse_last_mb;
h->parse_last_mb= mb;
if(pc->frame_start_found){
if(mb <= last_mb)
goto found;
}else
pc->frame_start_found = 1;
state= 7;
}
}
}
pc->state= state;
if(h->is_avc)
return next_avc;
return END_NOT_FOUND;
found:
pc->state=7;
pc->frame_start_found= 0;
if(h->is_avc)
return next_avc;
return i-(state&5) - 3*(state>7);
}
/**
* Parse NAL units of found picture and decode some basic information.
*
* @param s parser context.
* @param avctx codec context.
* @param buf buffer with field/frame data.
* @param buf_size size of the buffer.
*/
static inline int parse_nal_units(AVCodecParserContext *s,
AVCodecContext *avctx,
const uint8_t *buf, int buf_size)
{
H264Context *h = s->priv_data;
const uint8_t *buf_end = buf + buf_size;
unsigned int pps_id;
unsigned int slice_type;
int state = -1;
const uint8_t *ptr;
int q264 = buf_size >=4 && !memcmp("Q264", buf, 4);
/* set some sane default values */
s->pict_type = AV_PICTURE_TYPE_I;
s->key_frame = 0;
h->s.avctx= avctx;
h->sei_recovery_frame_cnt = -1;
h->sei_dpb_output_delay = 0;
h->sei_cpb_removal_delay = -1;
h->sei_buffering_period_present = 0;
if (!buf_size)
return 0;
for(;;) {
int src_length, dst_length, consumed, nalsize = 0;
if (h->is_avc) {
int i;
if (h->nal_length_size >= buf_end - buf) break;
nalsize = 0;
for (i = 0; i < h->nal_length_size; i++)
nalsize = (nalsize << 8) | *buf++;
if (nalsize <= 0 || nalsize > buf_end - buf) {
av_log(h->s.avctx, AV_LOG_ERROR, "AVC: nal size %d\n", nalsize);
break;
}
src_length = nalsize;
} else {
buf = avpriv_mpv_find_start_code(buf, buf_end, &state);
if(buf >= buf_end)
break;
--buf;
src_length = buf_end - buf;
}
switch (state & 0x1f) {
case NAL_SLICE:
case NAL_IDR_SLICE:
// Do not walk the whole buffer just to decode slice header
if (src_length > 20)
src_length = 20;
break;
}
ptr= ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
if (ptr==NULL || dst_length < 0)
break;
init_get_bits(&h->s.gb, ptr, 8*dst_length);
switch(h->nal_unit_type) {
case NAL_SPS:
ff_h264_decode_seq_parameter_set(h);
break;
case NAL_PPS:
ff_h264_decode_picture_parameter_set(h, h->s.gb.size_in_bits);
break;
case NAL_SEI:
ff_h264_decode_sei(h);
break;
case NAL_IDR_SLICE:
s->key_frame = 1;
/* fall through */
case NAL_SLICE:
get_ue_golomb_long(&h->s.gb); // skip first_mb_in_slice
slice_type = get_ue_golomb_31(&h->s.gb);
s->pict_type = golomb_to_pict_type[slice_type % 5];
if (h->sei_recovery_frame_cnt >= 0) {
/* key frame, since recovery_frame_cnt is set */
s->key_frame = 1;
}
pps_id= get_ue_golomb(&h->s.gb);
if(pps_id>=MAX_PPS_COUNT) {
av_log(h->s.avctx, AV_LOG_ERROR, "pps_id out of range\n");
return -1;
}
if(!h->pps_buffers[pps_id]) {
av_log(h->s.avctx, AV_LOG_ERROR, "non-existing PPS referenced\n");
return -1;
}
h->pps= *h->pps_buffers[pps_id];
if(!h->sps_buffers[h->pps.sps_id]) {
av_log(h->s.avctx, AV_LOG_ERROR, "non-existing SPS referenced\n");
return -1;
}
h->sps = *h->sps_buffers[h->pps.sps_id];
h->frame_num = get_bits(&h->s.gb, h->sps.log2_max_frame_num);
avctx->profile = ff_h264_get_profile(&h->sps);
avctx->level = h->sps.level_idc;
if(h->sps.frame_mbs_only_flag){
h->s.picture_structure= PICT_FRAME;
}else{
if(get_bits1(&h->s.gb)) { //field_pic_flag
h->s.picture_structure= PICT_TOP_FIELD + get_bits1(&h->s.gb); //bottom_field_flag
} else {
h->s.picture_structure= PICT_FRAME;
}
}
if(h->sps.pic_struct_present_flag) {
switch (h->sei_pic_struct) {
case SEI_PIC_STRUCT_TOP_FIELD:
case SEI_PIC_STRUCT_BOTTOM_FIELD:
s->repeat_pict = 0;
break;
case SEI_PIC_STRUCT_FRAME:
case SEI_PIC_STRUCT_TOP_BOTTOM:
case SEI_PIC_STRUCT_BOTTOM_TOP:
s->repeat_pict = 1;
break;
case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
s->repeat_pict = 2;
break;
case SEI_PIC_STRUCT_FRAME_DOUBLING:
s->repeat_pict = 3;
break;
case SEI_PIC_STRUCT_FRAME_TRIPLING:
s->repeat_pict = 5;
break;
default:
s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
break;
}
} else {
s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
}
return 0; /* no need to evaluate the rest */
}
buf += h->is_avc ? nalsize : consumed;
}
if (q264)
return 0;
/* didn't find a picture! */
av_log(h->s.avctx, AV_LOG_ERROR, "missing picture in access unit with size %d\n", buf_size);
return -1;
}
static int h264_parse(AVCodecParserContext *s,
AVCodecContext *avctx,
const uint8_t **poutbuf, int *poutbuf_size,
const uint8_t *buf, int buf_size)
{
H264Context *h = s->priv_data;
ParseContext *pc = &h->s.parse_context;
int next;
if (!h->got_first) {
h->got_first = 1;
if (avctx->extradata_size) {
h->s.avctx = avctx;
// must be done like in decoder, otherwise opening the parser,
// letting it create extradata and then closing and opening again
// will cause has_b_frames to be always set.
// Note that estimate_timings_from_pts does exactly this.
if (!avctx->has_b_frames)
h->s.low_delay = 1;
ff_h264_decode_extradata(h, avctx->extradata, avctx->extradata_size);
}
}
if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
next= buf_size;
}else{
next= ff_h264_find_frame_end(h, buf, buf_size);
if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
*poutbuf = NULL;
*poutbuf_size = 0;
return buf_size;
}
if(next<0 && next != END_NOT_FOUND){
av_assert1(pc->last_index + next >= 0 );
ff_h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); //update state
}
}
parse_nal_units(s, avctx, buf, buf_size);
if (h->sei_cpb_removal_delay >= 0) {
s->dts_sync_point = h->sei_buffering_period_present;
s->dts_ref_dts_delta = h->sei_cpb_removal_delay;
s->pts_dts_delta = h->sei_dpb_output_delay;
} else {
s->dts_sync_point = INT_MIN;
s->dts_ref_dts_delta = INT_MIN;
s->pts_dts_delta = INT_MIN;
}
if (s->flags & PARSER_FLAG_ONCE) {
s->flags &= PARSER_FLAG_COMPLETE_FRAMES;
}
*poutbuf = buf;
*poutbuf_size = buf_size;
return next;
}
static int h264_split(AVCodecContext *avctx,
const uint8_t *buf, int buf_size)
{
int i;
uint32_t state = -1;
int has_sps= 0;
for(i=0; i<=buf_size; i++){
if((state&0xFFFFFF1F) == 0x107)
has_sps=1;
/* if((state&0xFFFFFF1F) == 0x101 || (state&0xFFFFFF1F) == 0x102 || (state&0xFFFFFF1F) == 0x105){
}*/
if((state&0xFFFFFF00) == 0x100 && (state&0xFFFFFF1F) != 0x107 && (state&0xFFFFFF1F) != 0x108 && (state&0xFFFFFF1F) != 0x109){
if(has_sps){
while(i>4 && buf[i-5]==0) i--;
return i-4;
}
}
if (i<buf_size)
state= (state<<8) | buf[i];
}
return 0;
}
static void close(AVCodecParserContext *s)
{
H264Context *h = s->priv_data;
ParseContext *pc = &h->s.parse_context;
av_free(pc->buffer);
ff_h264_free_context(h);
}
static int init(AVCodecParserContext *s)
{
H264Context *h = s->priv_data;
h->thread_context[0] = h;
h->s.slice_context_count = 1;
return 0;
}
AVCodecParser ff_h264_parser = {
.codec_ids = { AV_CODEC_ID_H264 },
.priv_data_size = sizeof(H264Context),
.parser_init = init,
.parser_parse = h264_parse,
.parser_close = close,
.split = h264_split,
};
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