| /* |
| * 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; |
| 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_freep(&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, |
| }; |
