| /* | |
| * 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 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 | |
| * 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) | |
| { | |
| int i; | |
| int8_t *start; | |
| static const uint8_t valid_pu_types[] = { | |
| 0x00, 0x10, 0x20, 0x30, 0x08, 0x48, 0xC8, 0xE8, 0x0A, 0x0C, 0x0D, 0x0E, | |
| 0x4C, 0x09, 0xCC, 0x88, 0xCB | |
| }; | |
| if (offset < 0 || pc->index - 13 < offset) | |
| return 0; | |
| start = pc->buffer + offset; | |
| pu->pu_type = start[4]; | |
| pu->next_pu_offset = AV_RB32(start + 5); | |
| pu->prev_pu_offset = AV_RB32(start + 9); | |
| /* Check for valid parse code */ | |
| for (i = 0; i < 17; i++) | |
| if (valid_pu_types[i] == pu->pu_type) | |
| break; | |
| if (i == 17) | |
| return 0; | |
| if (pu->pu_type == 0x10 && pu->next_pu_offset == 0x00) | |
| pu->next_pu_offset = 13; /* The length of a parse info header */ | |
| /* Check if the parse offsets are somewhat sane */ | |
| if ((pu->next_pu_offset && pu->next_pu_offset < 13) || | |
| (pu->prev_pu_offset && pu->prev_pu_offset < 13)) | |
| return 0; | |
| 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) { | |
| memmove(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)); | |
| if (!new_buffer) | |
| return AVERROR(ENOMEM); | |
| 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); | |
| if (!new_buffer) | |
| return AVERROR(ENOMEM); | |
| 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 < pc->dirac_unit_size + 13LL + 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 && pu1.prev_pu_offset >= 13) { | |
| uint8_t *cur_pu = pc->buffer + | |
| pc->index - 13 - pu1.prev_pu_offset; | |
| int64_t pts = AV_RB32(cur_pu + 13); | |
| if (s->last_pts == 0 && s->last_dts == 0) | |
| s->dts = pts - 1; | |
| else if (s->last_dts != AV_NOPTS_VALUE) | |
| 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_freep(&pc->buffer); | |
| } | |
| const AVCodecParser ff_dirac_parser = { | |
| .codec_ids = { AV_CODEC_ID_DIRAC }, | |
| .priv_data_size = sizeof(DiracParseContext), | |
| .parser_parse = dirac_parse, | |
| .parser_close = dirac_parse_close, | |
| }; |