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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 Libav.
*
* Libav 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.
*
* Libav 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 Libav; 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>
*/
#include "libavutil/attributes.h"
#include "parser.h"
#include "h264data.h"
#include "golomb.h"
#include "internal.h"
#include "mpegutils.h"
#include <assert.h>
typedef struct H264ParseContext {
H264Context h;
ParseContext pc;
int got_first;
} H264ParseContext;
static int h264_find_frame_end(H264ParseContext *p, const uint8_t *buf,
int buf_size)
{
H264Context *h = &p->h;
int i;
uint32_t state;
ParseContext *pc = &p->pc;
// mb_addr= pc->mb_addr - 1;
state = pc->state;
if (state > 13)
state = 7;
for (i = 0; i < buf_size; i++) {
if (state == 7) {
i += h->h264dsp.startcode_find_candidate(buf + i, buf_size - i);
if (i < buf_size)
state = 2;
} 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 nalu_type = buf[i] & 0x1F;
if (nalu_type == NAL_SEI || nalu_type == NAL_SPS ||
nalu_type == NAL_PPS || nalu_type == NAL_AUD) {
if (pc->frame_start_found) {
i++;
goto found;
}
} else if (nalu_type == NAL_SLICE || nalu_type == NAL_DPA ||
nalu_type == NAL_IDR_SLICE) {
if (pc->frame_start_found) {
state += 8;
continue;
} else
pc->frame_start_found = 1;
}
state = 7;
} else {
// first_mb_in_slice is 0, probably the first nal of a new slice
if (buf[i] & 0x80)
goto found;
state = 7;
}
}
pc->state = state;
return END_NOT_FOUND;
found:
pc->state = 7;
pc->frame_start_found = 0;
return i - (state & 5);
}
static int scan_mmco_reset(AVCodecParserContext *s)
{
H264ParseContext *p = s->priv_data;
H264Context *h = &p->h;
h->slice_type_nos = s->pict_type & 3;
if (h->pps.redundant_pic_cnt_present)
get_ue_golomb(&h->gb); // redundant_pic_count
if (ff_set_ref_count(h) < 0)
return AVERROR_INVALIDDATA;
if (h->slice_type_nos != AV_PICTURE_TYPE_I) {
int list;
for (list = 0; list < h->list_count; list++) {
if (get_bits1(&h->gb)) {
int index;
for (index = 0; ; index++) {
unsigned int reordering_of_pic_nums_idc = get_ue_golomb_31(&h->gb);
if (reordering_of_pic_nums_idc < 3)
get_ue_golomb(&h->gb);
else if (reordering_of_pic_nums_idc > 3) {
av_log(h->avctx, AV_LOG_ERROR,
"illegal reordering_of_pic_nums_idc %d\n",
reordering_of_pic_nums_idc);
return AVERROR_INVALIDDATA;
} else
break;
if (index >= h->ref_count[list]) {
av_log(h->avctx, AV_LOG_ERROR,
"reference count %d overflow\n", index);
return AVERROR_INVALIDDATA;
}
}
}
}
}
if ((h->pps.weighted_pred && h->slice_type_nos == AV_PICTURE_TYPE_P) ||
(h->pps.weighted_bipred_idc == 1 && h->slice_type_nos == AV_PICTURE_TYPE_B))
ff_pred_weight_table(h);
if (get_bits1(&h->gb)) { // adaptive_ref_pic_marking_mode_flag
int i;
for (i = 0; i < MAX_MMCO_COUNT; i++) {
MMCOOpcode opcode = get_ue_golomb_31(&h->gb);
if (opcode > (unsigned) MMCO_LONG) {
av_log(h->avctx, AV_LOG_ERROR,
"illegal memory management control operation %d\n",
opcode);
return AVERROR_INVALIDDATA;
}
if (opcode == MMCO_END)
return 0;
else if (opcode == MMCO_RESET)
return 1;
if (opcode == MMCO_SHORT2UNUSED || opcode == MMCO_SHORT2LONG)
get_ue_golomb(&h->gb);
if (opcode == MMCO_SHORT2LONG || opcode == MMCO_LONG2UNUSED ||
opcode == MMCO_LONG || opcode == MMCO_SET_MAX_LONG)
get_ue_golomb_31(&h->gb);
}
}
return 0;
}
/**
* 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)
{
H264ParseContext *p = s->priv_data;
H264Context *h = &p->h;
const uint8_t *buf_end = buf + buf_size;
unsigned int pps_id;
unsigned int slice_type;
int state = -1, got_reset = 0;
const uint8_t *ptr;
int field_poc[2];
/* set some sane default values */
s->pict_type = AV_PICTURE_TYPE_I;
s->key_frame = 0;
s->picture_structure = AV_PICTURE_STRUCTURE_UNKNOWN;
h->avctx = avctx;
ff_h264_reset_sei(h);
if (!buf_size)
return 0;
for (;;) {
int src_length, dst_length, consumed;
buf = avpriv_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 ((state & 0x1f) == NAL_IDR_SLICE || ((state >> 5) & 0x3) == 0) {
/* IDR or disposable slice
* No need to decode many bytes because MMCOs shall not be present. */
if (src_length > 60)
src_length = 60;
} else {
/* To decode up to MMCOs */
if (src_length > 1000)
src_length = 1000;
}
break;
}
ptr = ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
if (!ptr || dst_length < 0)
break;
init_get_bits(&h->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->gb.size_in_bits);
break;
case NAL_SEI:
ff_h264_decode_sei(h);
break;
case NAL_IDR_SLICE:
s->key_frame = 1;
h->prev_frame_num = 0;
h->prev_frame_num_offset = 0;
h->prev_poc_msb =
h->prev_poc_lsb = 0;
/* fall through */
case NAL_SLICE:
get_ue_golomb(&h->gb); // skip first_mb_in_slice
slice_type = get_ue_golomb_31(&h->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->gb);
if (pps_id >= MAX_PPS_COUNT) {
av_log(h->avctx, AV_LOG_ERROR,
"pps_id %u out of range\n", pps_id);
return -1;
}
if (!h->pps_buffers[pps_id]) {
av_log(h->avctx, AV_LOG_ERROR,
"non-existing PPS %u referenced\n", pps_id);
return -1;
}
h->pps = *h->pps_buffers[pps_id];
if (!h->sps_buffers[h->pps.sps_id]) {
av_log(h->avctx, AV_LOG_ERROR,
"non-existing SPS %u referenced\n", h->pps.sps_id);
return -1;
}
h->sps = *h->sps_buffers[h->pps.sps_id];
h->frame_num = get_bits(&h->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->picture_structure = PICT_FRAME;
} else {
if (get_bits1(&h->gb)) { // field_pic_flag
h->picture_structure = PICT_TOP_FIELD + get_bits1(&h->gb); // bottom_field_flag
} else {
h->picture_structure = PICT_FRAME;
}
}
if (h->nal_unit_type == NAL_IDR_SLICE)
get_ue_golomb(&h->gb); /* idr_pic_id */
if (h->sps.poc_type == 0) {
h->poc_lsb = get_bits(&h->gb, h->sps.log2_max_poc_lsb);
if (h->pps.pic_order_present == 1 &&
h->picture_structure == PICT_FRAME)
h->delta_poc_bottom = get_se_golomb(&h->gb);
}
if (h->sps.poc_type == 1 &&
!h->sps.delta_pic_order_always_zero_flag) {
h->delta_poc[0] = get_se_golomb(&h->gb);
if (h->pps.pic_order_present == 1 &&
h->picture_structure == PICT_FRAME)
h->delta_poc[1] = get_se_golomb(&h->gb);
}
/* Decode POC of this picture.
* The prev_ values needed for decoding POC of the next picture are not set here. */
field_poc[0] = field_poc[1] = INT_MAX;
ff_init_poc(h, field_poc, &s->output_picture_number);
/* Continue parsing to check if MMCO_RESET is present.
* FIXME: MMCO_RESET could appear in non-first slice.
* Maybe, we should parse all undisposable non-IDR slice of this
* picture until encountering MMCO_RESET in a slice of it. */
if (h->nal_ref_idc && h->nal_unit_type != NAL_IDR_SLICE) {
got_reset = scan_mmco_reset(s);
if (got_reset < 0)
return got_reset;
}
/* Set up the prev_ values for decoding POC of the next picture. */
h->prev_frame_num = got_reset ? 0 : h->frame_num;
h->prev_frame_num_offset = got_reset ? 0 : h->frame_num_offset;
if (h->nal_ref_idc != 0) {
if (!got_reset) {
h->prev_poc_msb = h->poc_msb;
h->prev_poc_lsb = h->poc_lsb;
} else {
h->prev_poc_msb = 0;
h->prev_poc_lsb =
h->picture_structure == PICT_BOTTOM_FIELD ? 0 : field_poc[0];
}
}
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->picture_structure == PICT_FRAME ? 1 : 0;
break;
}
} else {
s->repeat_pict = h->picture_structure == PICT_FRAME ? 1 : 0;
}
if (h->picture_structure == PICT_FRAME) {
s->picture_structure = AV_PICTURE_STRUCTURE_FRAME;
if (h->sps.pic_struct_present_flag) {
switch (h->sei_pic_struct) {
case SEI_PIC_STRUCT_TOP_BOTTOM:
case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
s->field_order = AV_FIELD_TT;
break;
case SEI_PIC_STRUCT_BOTTOM_TOP:
case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
s->field_order = AV_FIELD_BB;
break;
default:
s->field_order = AV_FIELD_PROGRESSIVE;
break;
}
} else {
if (field_poc[0] < field_poc[1])
s->field_order = AV_FIELD_TT;
else if (field_poc[0] > field_poc[1])
s->field_order = AV_FIELD_BB;
else
s->field_order = AV_FIELD_PROGRESSIVE;
}
} else {
if (h->picture_structure == PICT_TOP_FIELD)
s->picture_structure = AV_PICTURE_STRUCTURE_TOP_FIELD;
else
s->picture_structure = AV_PICTURE_STRUCTURE_BOTTOM_FIELD;
s->field_order = AV_FIELD_UNKNOWN;
}
return 0; /* no need to evaluate the rest */
}
buf += consumed;
}
/* didn't find a picture! */
av_log(h->avctx, AV_LOG_ERROR, "missing picture in access unit\n");
return -1;
}
static int h264_parse(AVCodecParserContext *s,
AVCodecContext *avctx,
const uint8_t **poutbuf, int *poutbuf_size,
const uint8_t *buf, int buf_size)
{
H264ParseContext *p = s->priv_data;
H264Context *h = &p->h;
ParseContext *pc = &p->pc;
int next;
if (!p->got_first) {
p->got_first = 1;
if (avctx->extradata_size) {
h->avctx = avctx;
// must be done like in the decoder.
// otherwise opening the parser, creating extradata,
// and then closing and opening again
// will cause has_b_frames to be always set.
// NB: estimate_timings_from_pts behaves exactly like this.
if (!avctx->has_b_frames)
h->low_delay = 1;
ff_h264_decode_extradata(h);
}
}
if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
next = buf_size;
} else {
next = h264_find_frame_end(p, 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) {
assert(pc->last_index + next >= 0);
h264_find_frame_end(p, &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) != 0x106 &&
(state & 0xFFFFFF1F) != 0x107 && (state & 0xFFFFFF1F) != 0x108 &&
(state & 0xFFFFFF1F) != 0x109 && (state & 0xFFFFFF1F) != 0x10d &&
(state & 0xFFFFFF1F) != 0x10f) {
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)
{
H264ParseContext *p = s->priv_data;
H264Context *h = &p->h;
ParseContext *pc = &p->pc;
av_free(pc->buffer);
ff_h264_free_context(h);
}
static av_cold int init(AVCodecParserContext *s)
{
H264ParseContext *p = s->priv_data;
H264Context *h = &p->h;
h->thread_context[0] = h;
h->slice_context_count = 1;
ff_h264dsp_init(&h->h264dsp, 8, 1);
return 0;
}
AVCodecParser ff_h264_parser = {
.codec_ids = { AV_CODEC_ID_H264 },
.priv_data_size = sizeof(H264ParseContext),
.parser_init = init,
.parser_parse = h264_parse,
.parser_close = close,
.split = h264_split,
};