yading@10: /*
yading@10:  * Dirac parser
yading@10:  *
yading@10:  * Copyright (c) 2007-2008 Marco Gerards <marco@gnu.org>
yading@10:  * Copyright (c) 2008 BBC, Anuradha Suraparaju <asuraparaju@gmail.com>
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: /**
yading@10:  * @file
yading@10:  * Dirac Parser
yading@10:  * @author Marco Gerards <marco@gnu.org>
yading@10:  */
yading@10: 
yading@10: #include <string.h>
yading@10: 
yading@10: #include "libavutil/intreadwrite.h"
yading@10: #include "libavutil/mem.h"
yading@10: #include "parser.h"
yading@10: 
yading@10: #define DIRAC_PARSE_INFO_PREFIX 0x42424344
yading@10: 
yading@10: /**
yading@10:  * Find the end of the current frame in the bitstream.
yading@10:  * @return the position of the first byte of the next frame or -1
yading@10:  */
yading@10: typedef struct DiracParseContext {
yading@10:     int state;
yading@10:     int is_synced;
yading@10:     int sync_offset;
yading@10:     int header_bytes_needed;
yading@10:     int overread_index;
yading@10:     int buffer_size;
yading@10:     int index;
yading@10:     uint8_t *buffer;
yading@10:     int dirac_unit_size;
yading@10:     uint8_t *dirac_unit;
yading@10: } DiracParseContext;
yading@10: 
yading@10: static int find_frame_end(DiracParseContext *pc,
yading@10:                           const uint8_t *buf, int buf_size)
yading@10: {
yading@10:     uint32_t state = pc->state;
yading@10:     int i = 0;
yading@10: 
yading@10:     if (!pc->is_synced) {
yading@10:         for (i = 0; i < buf_size; i++) {
yading@10:             state = (state << 8) | buf[i];
yading@10:             if (state == DIRAC_PARSE_INFO_PREFIX) {
yading@10:                 state                   = -1;
yading@10:                 pc->is_synced           = 1;
yading@10:                 pc->header_bytes_needed = 9;
yading@10:                 pc->sync_offset         = i;
yading@10:                 break;
yading@10:             }
yading@10:         }
yading@10:     }
yading@10: 
yading@10:     if (pc->is_synced) {
yading@10:         pc->sync_offset = 0;
yading@10:         for (; i < buf_size; i++) {
yading@10:             if (state == DIRAC_PARSE_INFO_PREFIX) {
yading@10:                 if ((buf_size-i) >= pc->header_bytes_needed) {
yading@10:                     pc->state = -1;
yading@10:                     return i + pc->header_bytes_needed;
yading@10:                 } else {
yading@10:                     pc->header_bytes_needed = 9-(buf_size-i);
yading@10:                     break;
yading@10:                 }
yading@10:             } else
yading@10:               state = (state << 8) | buf[i];
yading@10:         }
yading@10:     }
yading@10:     pc->state = state;
yading@10:     return -1;
yading@10: }
yading@10: 
yading@10: typedef struct DiracParseUnit
yading@10: {
yading@10:     int next_pu_offset;
yading@10:     int prev_pu_offset;
yading@10:     uint8_t pu_type;
yading@10: } DiracParseUnit;
yading@10: 
yading@10: static int unpack_parse_unit(DiracParseUnit *pu, DiracParseContext *pc,
yading@10:                              int offset)
yading@10: {
yading@10:     uint8_t *start = pc->buffer + offset;
yading@10:     uint8_t *end   = pc->buffer + pc->index;
yading@10:     if (start < pc->buffer || (start+13 > end))
yading@10:         return 0;
yading@10:     pu->pu_type = start[4];
yading@10: 
yading@10:     pu->next_pu_offset = AV_RB32(start+5);
yading@10:     pu->prev_pu_offset = AV_RB32(start+9);
yading@10: 
yading@10:     if (pu->pu_type == 0x10 && pu->next_pu_offset == 0)
yading@10:         pu->next_pu_offset = 13;
yading@10: 
yading@10:     return 1;
yading@10: }
yading@10: 
yading@10: static int dirac_combine_frame(AVCodecParserContext *s, AVCodecContext *avctx,
yading@10:                                int next, const uint8_t **buf, int *buf_size)
yading@10: {
yading@10:     int parse_timing_info = (s->pts == AV_NOPTS_VALUE &&
yading@10:                              s->dts == AV_NOPTS_VALUE);
yading@10:     DiracParseContext *pc = s->priv_data;
yading@10: 
yading@10:     if (pc->overread_index) {
yading@10:         memcpy(pc->buffer, pc->buffer + pc->overread_index,
yading@10:                pc->index - pc->overread_index);
yading@10:         pc->index -= pc->overread_index;
yading@10:         pc->overread_index = 0;
yading@10:         if (*buf_size == 0 && pc->buffer[4] == 0x10) {
yading@10:             *buf      = pc->buffer;
yading@10:             *buf_size = pc->index;
yading@10:             return 0;
yading@10:         }
yading@10:     }
yading@10: 
yading@10:     if ( next == -1) {
yading@10:         /* Found a possible frame start but not a frame end */
yading@10:         void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
yading@10:                                            pc->index + (*buf_size -
yading@10:                                                         pc->sync_offset));
yading@10:         pc->buffer = new_buffer;
yading@10:         memcpy(pc->buffer+pc->index, (*buf + pc->sync_offset),
yading@10:                *buf_size - pc->sync_offset);
yading@10:         pc->index += *buf_size - pc->sync_offset;
yading@10:         return -1;
yading@10:     } else {
yading@10:         /* Found a possible frame start and a  possible frame end */
yading@10:         DiracParseUnit pu1, pu;
yading@10:         void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
yading@10:                                            pc->index + next);
yading@10:         pc->buffer = new_buffer;
yading@10:         memcpy(pc->buffer + pc->index, *buf, next);
yading@10:         pc->index += next;
yading@10: 
yading@10:         /* Need to check if we have a valid Parse Unit. We can't go by the
yading@10:          * sync pattern 'BBCD' alone because arithmetic coding of the residual
yading@10:          * and motion data can cause the pattern triggering a false start of
yading@10:          * frame. So check if the previous parse offset of the next parse unit
yading@10:          * is equal to the next parse offset of the current parse unit then
yading@10:          * we can be pretty sure that we have a valid parse unit */
yading@10:         if (!unpack_parse_unit(&pu1, pc, pc->index - 13)                     ||
yading@10:             !unpack_parse_unit(&pu, pc, pc->index - 13 - pu1.prev_pu_offset) ||
yading@10:             pu.next_pu_offset != pu1.prev_pu_offset                          ||
yading@10:             pc->index < pc->dirac_unit_size + 13LL + pu1.prev_pu_offset
yading@10:         ) {
yading@10:             pc->index -= 9;
yading@10:             *buf_size = next-9;
yading@10:             pc->header_bytes_needed = 9;
yading@10:             return -1;
yading@10:         }
yading@10: 
yading@10:         /* All non-frame data must be accompanied by frame data. This is to
yading@10:          * ensure that pts is set correctly. So if the current parse unit is
yading@10:          * not frame data, wait for frame data to come along */
yading@10: 
yading@10:         pc->dirac_unit = pc->buffer + pc->index - 13 -
yading@10:                          pu1.prev_pu_offset - pc->dirac_unit_size;
yading@10: 
yading@10:         pc->dirac_unit_size += pu.next_pu_offset;
yading@10: 
yading@10:         if ((pu.pu_type&0x08) != 0x08) {
yading@10:             pc->header_bytes_needed = 9;
yading@10:             *buf_size = next;
yading@10:             return -1;
yading@10:         }
yading@10: 
yading@10:         /* Get the picture number to set the pts and dts*/
yading@10:         if (parse_timing_info) {
yading@10:             uint8_t *cur_pu = pc->buffer +
yading@10:                               pc->index - 13 - pu1.prev_pu_offset;
yading@10:             int pts =  AV_RB32(cur_pu + 13);
yading@10:             if (s->last_pts == 0 && s->last_dts == 0)
yading@10:                 s->dts = pts - 1;
yading@10:             else
yading@10:                 s->dts = s->last_dts+1;
yading@10:             s->pts = pts;
yading@10:             if (!avctx->has_b_frames && (cur_pu[4] & 0x03))
yading@10:                 avctx->has_b_frames = 1;
yading@10:         }
yading@10:         if (avctx->has_b_frames && s->pts == s->dts)
yading@10:              s->pict_type = AV_PICTURE_TYPE_B;
yading@10: 
yading@10:         /* Finally have a complete Dirac data unit */
yading@10:         *buf      = pc->dirac_unit;
yading@10:         *buf_size = pc->dirac_unit_size;
yading@10: 
yading@10:         pc->dirac_unit_size     = 0;
yading@10:         pc->overread_index      = pc->index-13;
yading@10:         pc->header_bytes_needed = 9;
yading@10:     }
yading@10:     return next;
yading@10: }
yading@10: 
yading@10: static int dirac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
yading@10:                        const uint8_t **poutbuf, int *poutbuf_size,
yading@10:                        const uint8_t *buf, int buf_size)
yading@10: {
yading@10:     DiracParseContext *pc = s->priv_data;
yading@10:     int next;
yading@10: 
yading@10:     *poutbuf = NULL;
yading@10:     *poutbuf_size = 0;
yading@10: 
yading@10:     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
yading@10:         next = buf_size;
yading@10:         *poutbuf = buf;
yading@10:         *poutbuf_size = buf_size;
yading@10:         /* Assume that data has been packetized into an encapsulation unit. */
yading@10:     } else {
yading@10:         next = find_frame_end(pc, buf, buf_size);
yading@10:         if (!pc->is_synced && next == -1) {
yading@10:             /* No frame start found yet. So throw away the entire buffer. */
yading@10:             return buf_size;
yading@10:         }
yading@10: 
yading@10:         if (dirac_combine_frame(s, avctx, next, &buf, &buf_size) < 0) {
yading@10:             return buf_size;
yading@10:         }
yading@10:     }
yading@10: 
yading@10:     *poutbuf = buf;
yading@10:     *poutbuf_size = buf_size;
yading@10:     return next;
yading@10: }
yading@10: 
yading@10: static void dirac_parse_close(AVCodecParserContext *s)
yading@10: {
yading@10:     DiracParseContext *pc = s->priv_data;
yading@10: 
yading@10:     if (pc->buffer_size > 0)
yading@10:         av_free(pc->buffer);
yading@10: }
yading@10: 
yading@10: AVCodecParser ff_dirac_parser = {
yading@10:     .codec_ids      = { AV_CODEC_ID_DIRAC },
yading@10:     .priv_data_size = sizeof(DiracParseContext),
yading@10:     .parser_parse   = dirac_parse,
yading@10:     .parser_close   = dirac_parse_close,
yading@10: };