/* * Dirac parser * * Copyright (c) 2007-2008 Marco Gerards <marco@gnu.org> * Copyright (c) 2008 BBC, Anuradha Suraparaju <asuraparaju@gmail.com> * * 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 * Dirac Parser * @author Marco Gerards <marco@gnu.org> */ #include <string.h> #include "libavutil/intreadwrite.h"#include "libavutil/mem.h"#include "parser.h" #define DIRAC_PARSE_INFO_PREFIX 0x42424344 /** * Find the end of the current frame in the bitstream. * @return the position of the first byte of the next frame or -1 */typedef struct DiracParseContext {    int state;    int is_synced;    int sync_offset;    int header_bytes_needed;    int overread_index;    int buffer_size;    int index;    uint8_t *buffer;    int dirac_unit_size;    uint8_t *dirac_unit;} DiracParseContext; static int find_frame_end(DiracParseContext *pc,                          const uint8_t *buf, int buf_size){    uint32_t state = pc->state;    int i = 0;     if (!pc->is_synced) {        for (i = 0; i < buf_size; i++) {            state = (state << 8) | buf[i];            if (state == DIRAC_PARSE_INFO_PREFIX) {                state                   = -1;                pc->is_synced           = 1;                pc->header_bytes_needed = 9;                pc->sync_offset         = i;                break;            }        }    }     if (pc->is_synced) {        pc->sync_offset = 0;        for (; i < buf_size; i++) {            if (state == DIRAC_PARSE_INFO_PREFIX) {                if ((buf_size-i) >= pc->header_bytes_needed) {                    pc->state = -1;                    return i + pc->header_bytes_needed;                } else {                    pc->header_bytes_needed = 9-(buf_size-i);                    break;                }            } else              state = (state << 8) | buf[i];        }    }    pc->state = state;    return -1;} typedef struct DiracParseUnit{    int next_pu_offset;    int prev_pu_offset;    uint8_t pu_type;} DiracParseUnit; static int unpack_parse_unit(DiracParseUnit *pu, DiracParseContext *pc,                             int offset){    uint8_t *start = pc->buffer + offset;    uint8_t *end   = pc->buffer + pc->index;    if (start < pc->buffer || (start+13 > end))        return 0;    pu->pu_type = start[4];     pu->next_pu_offset = AV_RB32(start+5);    pu->prev_pu_offset = AV_RB32(start+9);     if (pu->pu_type == 0x10 && pu->next_pu_offset == 0)        pu->next_pu_offset = 13;     return 1;} static int dirac_combine_frame(AVCodecParserContext *s, AVCodecContext *avctx,                               int next, const uint8_t **buf, int *buf_size){    int parse_timing_info = (s->pts == AV_NOPTS_VALUE &&                             s->dts == AV_NOPTS_VALUE);    DiracParseContext *pc = s->priv_data;     if (pc->overread_index) {        memcpy(pc->buffer, pc->buffer + pc->overread_index,               pc->index - pc->overread_index);        pc->index -= pc->overread_index;        pc->overread_index = 0;        if (*buf_size == 0 && pc->buffer[4] == 0x10) {            *buf      = pc->buffer;            *buf_size = pc->index;            return 0;        }    }     if ( next == -1) {        /* Found a possible frame start but not a frame end */        void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,                                           pc->index + (*buf_size -                                                        pc->sync_offset));        pc->buffer = new_buffer;        memcpy(pc->buffer+pc->index, (*buf + pc->sync_offset),               *buf_size - pc->sync_offset);        pc->index += *buf_size - pc->sync_offset;        return -1;    } else {        /* Found a possible frame start and a  possible frame end */        DiracParseUnit pu1, pu;        void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,                                           pc->index + next);        pc->buffer = new_buffer;        memcpy(pc->buffer + pc->index, *buf, next);        pc->index += next;         /* Need to check if we have a valid Parse Unit. We can't go by the         * sync pattern 'BBCD' alone because arithmetic coding of the residual         * and motion data can cause the pattern triggering a false start of         * frame. So check if the previous parse offset of the next parse unit         * is equal to the next parse offset of the current parse unit then         * we can be pretty sure that we have a valid parse unit */        if (!unpack_parse_unit(&pu1, pc, pc->index - 13)                     ||            !unpack_parse_unit(&pu, pc, pc->index - 13 - pu1.prev_pu_offset) ||            pu.next_pu_offset != pu1.prev_pu_offset) {            pc->index -= 9;            *buf_size = next-9;            pc->header_bytes_needed = 9;            return -1;        }         /* All non-frame data must be accompanied by frame data. This is to         * ensure that pts is set correctly. So if the current parse unit is         * not frame data, wait for frame data to come along */         pc->dirac_unit = pc->buffer + pc->index - 13 -                         pu1.prev_pu_offset - pc->dirac_unit_size;         pc->dirac_unit_size += pu.next_pu_offset;         if ((pu.pu_type&0x08) != 0x08) {            pc->header_bytes_needed = 9;            *buf_size = next;            return -1;        }         /* Get the picture number to set the pts and dts*/        if (parse_timing_info) {            uint8_t *cur_pu = pc->buffer +                              pc->index - 13 - pu1.prev_pu_offset;            int pts =  AV_RB32(cur_pu + 13);            if (s->last_pts == 0 && s->last_dts == 0)                s->dts = pts - 1;            else                s->dts = s->last_dts+1;            s->pts = pts;            if (!avctx->has_b_frames && (cur_pu[4] & 0x03))                avctx->has_b_frames = 1;        }        if (avctx->has_b_frames && s->pts == s->dts)             s->pict_type = AV_PICTURE_TYPE_B;         /* Finally have a complete Dirac data unit */        *buf      = pc->dirac_unit;        *buf_size = pc->dirac_unit_size;         pc->dirac_unit_size     = 0;        pc->overread_index      = pc->index-13;        pc->header_bytes_needed = 9;    }    return next;} static int dirac_parse(AVCodecParserContext *s, AVCodecContext *avctx,                       const uint8_t **poutbuf, int *poutbuf_size,                       const uint8_t *buf, int buf_size){    DiracParseContext *pc = s->priv_data;    int next;     *poutbuf = NULL;    *poutbuf_size = 0;     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {        next = buf_size;        *poutbuf = buf;        *poutbuf_size = buf_size;        /* Assume that data has been packetized into an encapsulation unit. */    } else {        next = find_frame_end(pc, buf, buf_size);        if (!pc->is_synced && next == -1) {            /* No frame start found yet. So throw away the entire buffer. */            return buf_size;        }         if (dirac_combine_frame(s, avctx, next, &buf, &buf_size) < 0) {            return buf_size;        }    }     *poutbuf = buf;    *poutbuf_size = buf_size;    return next;} static void dirac_parse_close(AVCodecParserContext *s){    DiracParseContext *pc = s->priv_data;     if (pc->buffer_size > 0)        av_free(pc->buffer);} AVCodecParser ff_dirac_parser = {    .codec_ids      = { AV_CODEC_ID_DIRAC },    .priv_data_size = sizeof(DiracParseContext),    .parser_parse   = dirac_parse,    .parser_close   = dirac_parse_close,};