From e80b2b9c81716a5d9f559c04cfe69d76b04e4cd3 Mon Sep 17 00:00:00 2001 From: foo86 Date: Wed, 29 Apr 2015 14:14:55 +0300 Subject: [PATCH] avcodec/dca_parser: Extend DTS core sync word and fix existing check Check extended sync word for 16-bit LE and BE core streams to reduce probability of alias sync detection. Previously sync word extension was checked only for 14-bit streams (and this check did not properly work across buffer boundary). Use 64-bit parser state to make extended sync word detection work across buffer boundary. This is sufficient to make the sample in ticket #4492 parse successfully. Signed-off-by: Michael Niedermayer --- libavcodec/dca_parser.c | 42 ++++++++++++++++++++++++----------------- 1 file changed, 25 insertions(+), 17 deletions(-) diff --git a/libavcodec/dca_parser.c b/libavcodec/dca_parser.c index 979776077f..26e2f50875 100644 --- a/libavcodec/dca_parser.c +++ b/libavcodec/dca_parser.c @@ -32,13 +32,20 @@ typedef struct DCAParseContext { uint32_t lastmarker; int size; int framesize; - int hd_pos; } DCAParseContext; -#define IS_MARKER(state, i, buf, buf_size) \ - ((state == DCA_SYNCWORD_CORE_14B_LE && (i < buf_size - 2) && (buf[i + 1] & 0xF0) == 0xF0 && buf[i + 2] == 0x07) || \ - (state == DCA_SYNCWORD_CORE_14B_BE && (i < buf_size - 2) && buf[i + 1] == 0x07 && (buf[i + 2] & 0xF0) == 0xF0) || \ - state == DCA_SYNCWORD_CORE_LE || state == DCA_SYNCWORD_CORE_BE || state == DCA_SYNCWORD_SUBSTREAM) +#define IS_CORE_MARKER(state) \ + (((state & 0xFFFFFFFFF0FF) == (((uint64_t)DCA_SYNCWORD_CORE_14B_LE << 16) | 0xF007)) || \ + ((state & 0xFFFFFFFFFFF0) == (((uint64_t)DCA_SYNCWORD_CORE_14B_BE << 16) | 0x07F0)) || \ + ((state & 0xFFFFFFFF00FC) == (((uint64_t)DCA_SYNCWORD_CORE_LE << 16) | 0x00FC)) || \ + ((state & 0xFFFFFFFFFC00) == (((uint64_t)DCA_SYNCWORD_CORE_BE << 16) | 0xFC00))) + +#define IS_EXSS_MARKER(state) ((state & 0xFFFFFFFF) == DCA_SYNCWORD_SUBSTREAM) + +#define IS_MARKER(state) (IS_CORE_MARKER(state) || IS_EXSS_MARKER(state)) + +#define CORE_MARKER(state) ((state >> 16) & 0xFFFFFFFF) +#define EXSS_MARKER(state) (state & 0xFFFFFFFF) /** * Find the end of the current frame in the bitstream. @@ -48,20 +55,23 @@ static int dca_find_frame_end(DCAParseContext *pc1, const uint8_t *buf, int buf_size) { int start_found, i; - uint32_t state; + uint64_t state; ParseContext *pc = &pc1->pc; start_found = pc->frame_start_found; - state = pc->state; + state = pc->state64; i = 0; if (!start_found) { for (i = 0; i < buf_size; i++) { state = (state << 8) | buf[i]; - if (IS_MARKER(state, i, buf, buf_size)) { - if (!pc1->lastmarker || state == pc1->lastmarker || pc1->lastmarker == DCA_SYNCWORD_SUBSTREAM) { - start_found = 1; - pc1->lastmarker = state; + if (IS_MARKER(state)) { + if (!pc1->lastmarker || CORE_MARKER(state) == pc1->lastmarker || pc1->lastmarker == DCA_SYNCWORD_SUBSTREAM) { + start_found = 1; + if (IS_EXSS_MARKER(state)) + pc1->lastmarker = EXSS_MARKER(state); + else + pc1->lastmarker = CORE_MARKER(state); i++; break; } @@ -72,20 +82,18 @@ static int dca_find_frame_end(DCAParseContext *pc1, const uint8_t *buf, for (; i < buf_size; i++) { pc1->size++; state = (state << 8) | buf[i]; - if (state == DCA_SYNCWORD_SUBSTREAM && !pc1->hd_pos) - pc1->hd_pos = pc1->size; - if (IS_MARKER(state, i, buf, buf_size) && (state == pc1->lastmarker || pc1->lastmarker == DCA_SYNCWORD_SUBSTREAM)) { + if (IS_MARKER(state) && (CORE_MARKER(state) == pc1->lastmarker || pc1->lastmarker == DCA_SYNCWORD_SUBSTREAM)) { if (pc1->framesize > pc1->size) continue; pc->frame_start_found = 0; - pc->state = -1; + pc->state64 = -1; pc1->size = 0; - return i - 3; + return IS_EXSS_MARKER(state) ? i - 3 : i - 5; } } } pc->frame_start_found = start_found; - pc->state = state; + pc->state64 = state; return END_NOT_FOUND; }