int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s) { int i; uint32_t state = pc->state; /* EOF considered as end of frame */ if (buf_size == 0) return 0; /* 0 frame start -> 1/4 1 first_SEQEXT -> 0/2 2 first field start -> 3/0 3 second_SEQEXT -> 2/0 4 searching end */ for (i = 0; i < buf_size; i++) { av_assert1(pc->frame_start_found >= 0 && pc->frame_start_found <= 4); if (pc->frame_start_found & 1) { if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80) pc->frame_start_found--; else if (state == EXT_START_CODE + 2) { if ((buf[i] & 3) == 3) pc->frame_start_found = 0; else pc->frame_start_found = (pc->frame_start_found + 1) & 3; } state++; } else { i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1; if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) { i++; pc->frame_start_found = 4; } if (state == SEQ_END_CODE) { pc->frame_start_found = 0; pc->state=-1; return i+1; } if (pc->frame_start_found == 2 && state == SEQ_START_CODE) pc->frame_start_found = 0; if (pc->frame_start_found < 4 && state == EXT_START_CODE) pc->frame_start_found++; if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) { if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) { pc->frame_start_found = 0; pc->state = -1; return i - 3; } } if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) { ff_fetch_timestamp(s, i - 3, 1); } } } pc->state = state; return END_NOT_FOUND; }