diff options
author | Anuradha Suraparaju <anuradha@rd.bbc.co.uk> | 2008-12-22 03:01:39 +0300 |
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committer | Diego Biurrun <diego@biurrun.de> | 2008-12-22 03:01:39 +0300 |
commit | 64bfc5845bd4361d91f5bb7a7d76f416ee357ab6 (patch) | |
tree | 0a92947f69d310a3546c47efcc324c1ecfd6d13d /libavcodec/dirac_parser.c | |
parent | c4ff7c53e0135c3e0e65506f2ec95e1eeac6f069 (diff) |
Fix incorrectly constructed Dirac parse units that caused A/V sync loss.
Fixes issue 694.
patch by Anuradha Suraparaju, anuradha rd.bbc.co uk
Originally committed as revision 16261 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavcodec/dirac_parser.c')
-rw-r--r-- | libavcodec/dirac_parser.c | 205 |
1 files changed, 186 insertions, 19 deletions
diff --git a/libavcodec/dirac_parser.c b/libavcodec/dirac_parser.c index 199354a9c6..ac82dcabf1 100644 --- a/libavcodec/dirac_parser.c +++ b/libavcodec/dirac_parser.c @@ -1,7 +1,8 @@ /* * Dirac parser * - * Copyright (c) 2007 Marco Gerards <marco@gnu.org> + * Copyright (c) 2007-2008 Marco Gerards <marco@gnu.org> + * Copyright (c) 2008 BBC, Anuradha Suraparaju <asuraparaju@gmail.com> * * This file is part of FFmpeg. * @@ -34,42 +35,200 @@ * Finds the end of the current frame in the bitstream. * @return the position of the first byte of the next frame or -1 */ -static int find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size) +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; - - for (i = 0; i < buf_size; i++) { - state = (state << 8) | buf[i]; - if (state == DIRAC_PARSE_INFO_PREFIX) { - pc->frame_start_found ^= 1; - if (!pc->frame_start_found) { - pc->state = -1; - return i - 3; + 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; - return END_NOT_FOUND; + /* 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 = FF_B_TYPE; + + /* 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) { - ParseContext *pc = s->priv_data; + DiracParseContext *pc = s->priv_data; int next; + *poutbuf = NULL; + *poutbuf_size = 0; + if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) { next = buf_size; - }else{ + *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 (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { - *poutbuf = NULL; - *poutbuf_size = 0; + if (dirac_combine_frame(s, avctx, next, &buf, &buf_size) < 0) { return buf_size; } } @@ -79,10 +238,18 @@ static int dirac_parse(AVCodecParserContext *s, AVCodecContext *avctx, return next; } +static void dirac_parse_close(AVCodecParserContext *s) +{ + DiracParseContext *pc = s->priv_data; + + if (pc->buffer_size > 0) + av_free(pc->buffer); +} + AVCodecParser dirac_parser = { { CODEC_ID_DIRAC }, - sizeof(ParseContext), + sizeof(DiracParseContext), NULL, dirac_parse, - ff_parse_close, + dirac_parse_close, }; |