GCC Code Coverage Report
Directory: ../../../ffmpeg/ Exec Total Coverage
File: src/libavcodec/vc1_parser.c Lines: 118 140 84.3 %
Date: 2020-10-23 17:01:47 Branches: 82 114 71.9 %

Line Branch Exec Source
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/*
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 * VC-1 and WMV3 parser
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 * Copyright (c) 2006-2007 Konstantin Shishkov
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 * Partly based on vc9.c (c) 2005 Anonymous, Alex Beregszaszi, Michael Niedermayer
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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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/**
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 * @file
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 * VC-1 and WMV3 parser
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 */
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28
#include "libavutil/attributes.h"
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#include "parser.h"
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#include "vc1.h"
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#include "get_bits.h"
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#include "internal.h"
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34
/** The maximum number of bytes of a sequence, entry point or
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 *  frame header whose values we pay any attention to */
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#define UNESCAPED_THRESHOLD 37
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/** The maximum number of bytes of a sequence, entry point or
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 *  frame header which must be valid memory (because they are
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 *  used to update the bitstream cache in skip_bits() calls)
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 */
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#define UNESCAPED_LIMIT 144
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typedef enum {
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    NO_MATCH,
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    ONE_ZERO,
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    TWO_ZEROS,
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    ONE
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} VC1ParseSearchState;
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typedef struct VC1ParseContext {
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    ParseContext pc;
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    VC1Context v;
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    uint8_t prev_start_code;
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    size_t bytes_to_skip;
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    uint8_t unesc_buffer[UNESCAPED_LIMIT];
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    size_t unesc_index;
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    VC1ParseSearchState search_state;
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} VC1ParseContext;
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61
971
static void vc1_extract_header(AVCodecParserContext *s, AVCodecContext *avctx,
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                               const uint8_t *buf, int buf_size)
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{
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    /* Parse the header we just finished unescaping */
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971
    VC1ParseContext *vpc = s->priv_data;
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    GetBitContext gb;
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    int ret;
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971
    vpc->v.s.avctx = avctx;
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971
    vpc->v.parse_only = 1;
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971
    init_get_bits8(&gb, buf, buf_size);
71

971
    switch (vpc->prev_start_code) {
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9
    case VC1_CODE_SEQHDR & 0xFF:
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9
        ff_vc1_decode_sequence_header(avctx, &vpc->v, &gb);
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9
        break;
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14
    case VC1_CODE_ENTRYPOINT & 0xFF:
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14
        ff_vc1_decode_entry_point(avctx, &vpc->v, &gb);
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14
        break;
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305
    case VC1_CODE_FRAME & 0xFF:
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305
        if(vpc->v.profile < PROFILE_ADVANCED)
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            ret = ff_vc1_parse_frame_header    (&vpc->v, &gb);
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        else
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305
            ret = ff_vc1_parse_frame_header_adv(&vpc->v, &gb);
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84
305
        if (ret < 0)
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            break;
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        /* keep AV_PICTURE_TYPE_BI internal to VC1 */
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305
        if (vpc->v.s.pict_type == AV_PICTURE_TYPE_BI)
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            s->pict_type = AV_PICTURE_TYPE_B;
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        else
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305
            s->pict_type = vpc->v.s.pict_type;
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93
305
        if (avctx->ticks_per_frame > 1){
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            // process pulldown flags
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138
            s->repeat_pict = 1;
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            // Pulldown flags are only valid when 'broadcast' has been set.
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            // So ticks_per_frame will be 2
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138
            if (vpc->v.rff){
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                // repeat field
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                s->repeat_pict = 2;
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138
            }else if (vpc->v.rptfrm){
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                // repeat frames
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                s->repeat_pict = vpc->v.rptfrm * 2 + 1;
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            }
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        }else{
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167
            s->repeat_pict = 0;
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        }
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109

305
        if (vpc->v.broadcast && vpc->v.interlace && !vpc->v.psf)
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44
            s->field_order = vpc->v.tff ? AV_FIELD_TT : AV_FIELD_BB;
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        else
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261
            s->field_order = AV_FIELD_PROGRESSIVE;
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114
305
        break;
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    }
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971
    if (avctx->framerate.num)
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971
        avctx->time_base = av_inv_q(av_mul_q(avctx->framerate, (AVRational){avctx->ticks_per_frame, 1}));
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1942
    s->format = vpc->v.chromaformat == 1 ? AV_PIX_FMT_YUV420P
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971
                                         : AV_PIX_FMT_NONE;
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971
    if (avctx->width && avctx->height) {
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959
        s->width        = avctx->width;
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959
        s->height       = avctx->height;
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959
        s->coded_width  = FFALIGN(avctx->coded_width,  16);
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959
        s->coded_height = FFALIGN(avctx->coded_height, 16);
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    }
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971
}
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128
4746
static int vc1_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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    /* Here we do the searching for frame boundaries and headers at
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     * the same time. Only a minimal amount at the start of each
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     * header is unescaped. */
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4746
    VC1ParseContext *vpc = s->priv_data;
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4746
    int pic_found = vpc->pc.frame_start_found;
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4746
    uint8_t *unesc_buffer = vpc->unesc_buffer;
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4746
    size_t unesc_index = vpc->unesc_index;
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4746
    VC1ParseSearchState search_state = vpc->search_state;
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4746
    int start_code_found = 0;
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4746
    int next = END_NOT_FOUND;
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4746
    int i = vpc->bytes_to_skip;
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145

4746
    if (pic_found && buf_size == 0) {
146
        /* EOF considered as end of frame */
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14
        memset(unesc_buffer + unesc_index, 0, UNESCAPED_THRESHOLD - unesc_index);
148
14
        vc1_extract_header(s, avctx, unesc_buffer, unesc_index);
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14
        next = 0;
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    }
151
9846
    while (i < buf_size) {
152
        uint8_t b;
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5393
        start_code_found = 0;
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38288
        while (i < buf_size && unesc_index < UNESCAPED_THRESHOLD) {
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32986
            b = buf[i++];
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32986
            unesc_buffer[unesc_index++] = b;
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32986
            if (search_state <= ONE_ZERO)
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32765
                search_state = b ? NO_MATCH : search_state + 1;
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221
            else if (search_state == TWO_ZEROS) {
160
130
                if (b == 1)
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91
                    search_state = ONE;
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39
                else if (b > 1) {
163
39
                    if (b == 3)
164
22
                        unesc_index--; // swallow emulation prevention byte
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39
                    search_state = NO_MATCH;
166
                }
167
            }
168
            else { // search_state == ONE
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                // Header unescaping terminates early due to detection of next start code
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91
                search_state = NO_MATCH;
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91
                start_code_found = 1;
172
91
                break;
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            }
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        }
175

5393
        if ((s->flags & PARSER_FLAG_COMPLETE_FRAMES) &&
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                unesc_index >= UNESCAPED_THRESHOLD &&
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                vpc->prev_start_code == (VC1_CODE_FRAME & 0xFF))
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        {
179
            // No need to keep scanning the rest of the buffer for
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            // start codes if we know it contains a complete frame and
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            // we've already unescaped all we need of the frame header
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            vc1_extract_header(s, avctx, unesc_buffer, unesc_index);
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            break;
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        }
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5393
        if (unesc_index >= UNESCAPED_THRESHOLD && !start_code_found) {
186
57273
            while (i < buf_size) {
187
52860
                if (search_state == NO_MATCH) {
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27593
                    i += vpc->v.vc1dsp.startcode_find_candidate(buf + i, buf_size - i);
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27593
                    if (i < buf_size) {
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23222
                        search_state = ONE_ZERO;
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                    }
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27593
                    i++;
193
                } else {
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25267
                    b = buf[i++];
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25267
                    if (search_state == ONE_ZERO)
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23231
                        search_state = b ? NO_MATCH : TWO_ZEROS;
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2036
                    else if (search_state == TWO_ZEROS) {
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1170
                        if (b >= 1)
199
1170
                            search_state = b == 1 ? ONE : NO_MATCH;
200
                    }
201
                    else { // search_state == ONE
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866
                        search_state = NO_MATCH;
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866
                        start_code_found = 1;
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866
                        break;
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                    }
206
                }
207
            }
208
        }
209
5393
        if (start_code_found) {
210
957
            vc1_extract_header(s, avctx, unesc_buffer, unesc_index);
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212
957
            vpc->prev_start_code = b;
213
957
            unesc_index = 0;
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215
957
            if (!(s->flags & PARSER_FLAG_COMPLETE_FRAMES)) {
216

957
                if (!pic_found && (b == (VC1_CODE_FRAME & 0xFF) || b == (VC1_CODE_FIELD & 0xFF))) {
217
9
                    pic_found = 1;
218
                }
219

948
                else if (pic_found && b != (VC1_CODE_FIELD & 0xFF) && b != (VC1_CODE_SLICE & 0xFF)) {
220
293
                    next = i - 4;
221
293
                    pic_found = b == (VC1_CODE_FRAME & 0xFF);
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293
                    break;
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                }
224
            }
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        }
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    }
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228
4746
    vpc->pc.frame_start_found = pic_found;
229
4746
    vpc->unesc_index = unesc_index;
230
4746
    vpc->search_state = search_state;
231
232
4746
    if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
233
        next = buf_size;
234
    } else {
235
4746
        if (ff_combine_frame(&vpc->pc, next, &buf, &buf_size) < 0) {
236
4437
            vpc->bytes_to_skip = 0;
237
4437
            *poutbuf = NULL;
238
4437
            *poutbuf_size = 0;
239
4437
            return buf_size;
240
        }
241
    }
242
243
    /* If we return with a valid pointer to a combined frame buffer
244
     * then on the next call then we'll have been unhelpfully rewound
245
     * by up to 4 bytes (depending upon whether the start code
246
     * overlapped the input buffer, and if so by how much). We don't
247
     * want this: it will either cause spurious second detections of
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     * the start code we've already seen, or cause extra bytes to be
249
     * inserted at the start of the unescaped buffer. */
250
309
    vpc->bytes_to_skip = 4;
251

309
    if (next < 0 && next != END_NOT_FOUND)
252
        vpc->bytes_to_skip += next;
253
254
309
    *poutbuf = buf;
255
309
    *poutbuf_size = buf_size;
256
309
    return next;
257
}
258
259
static int vc1_split(AVCodecContext *avctx,
260
                           const uint8_t *buf, int buf_size)
261
{
262
    uint32_t state = -1;
263
    int charged = 0;
264
    const uint8_t *ptr = buf, *end = buf + buf_size;
265
266
    while (ptr < end) {
267
        ptr = avpriv_find_start_code(ptr, end, &state);
268
        if (state == VC1_CODE_SEQHDR || state == VC1_CODE_ENTRYPOINT) {
269
            charged = 1;
270
        } else if (charged && IS_MARKER(state))
271
            return ptr - 4 - buf;
272
    }
273
274
    return 0;
275
}
276
277
8
static av_cold int vc1_parse_init(AVCodecParserContext *s)
278
{
279
8
    VC1ParseContext *vpc = s->priv_data;
280
8
    vpc->v.s.slice_context_count = 1;
281
8
    vpc->v.first_pic_header_flag = 1;
282
8
    vpc->prev_start_code = 0;
283
8
    vpc->bytes_to_skip = 0;
284
8
    vpc->unesc_index = 0;
285
8
    vpc->search_state = NO_MATCH;
286
8
    return ff_vc1_init_common(&vpc->v);
287
}
288
289
AVCodecParser ff_vc1_parser = {
290
    .codec_ids      = { AV_CODEC_ID_VC1 },
291
    .priv_data_size = sizeof(VC1ParseContext),
292
    .parser_init    = vc1_parse_init,
293
    .parser_parse   = vc1_parse,
294
    .parser_close   = ff_parse_close,
295
    .split          = vc1_split,
296
};