Reading the caption data_group (ARIB STD-B24, Volume 3, 9.2). More...

#include "caption-common.h"
#include "packet-pes.h"

Include dependency graph for caption-data.h:

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Data Structures
struct	CaptionData_t

Macros
#define	CAPTION_MANAGEMENT_DGI_A 0x00

#define	CAPTION_MANAGEMENT_DGI_B 0x20

Typedefs
typedef struct CaptionData_t	CaptionData_t

Functions
bool	caption_data_check_crc16 (const uint8_t data, const uint16_t datalen, const uint16_t *crc16)

bool	caption_data_load (const PacketPES_t pes, CaptionData_t caption)

Detailed Description

Reading the caption data_group (ARIB STD-B24, Volume 3, 9.2).

Author: Jorge Pereira jpere.nosp@m.iran.nosp@m.@gmai.nosp@m.l.co.nosp@m.m

Date: Thu Aug 12 13:49:21 BRT 2010

Each caption PES carries a data_group:

* data_group_id(6) data_group_version(2) data_group_link_number(8)
* last_data_group_link_number(8) data_group_size(16)
* data_group_data_byte[data_group_size] CRC_16(16)
*

The data_group_id tells the content: 0x00/0x20 is the "caption management data" (groups A and B) and the others are the "caption statement data" of each language (see caption-management.h).

Definition in file caption-data.h.

Macro Definition Documentation

◆ CAPTION_MANAGEMENT_DGI_A

#define CAPTION_MANAGEMENT_DGI_A 0x00

data_group_id of the "caption management data", group A.

Definition at line 25 of file caption-data.h.

◆ CAPTION_MANAGEMENT_DGI_B

#define CAPTION_MANAGEMENT_DGI_B 0x20

data_group_id of the "caption management data", group B.

Definition at line 26 of file caption-data.h.

Typedef Documentation

◆ CaptionData_t

typedef struct CaptionData_t CaptionData_t

data_group loaded by caption_data_load().

Function Documentation

◆ caption_data_check_crc16()

bool caption_data_check_crc16	(	const uint8_t *	data,
		const uint16_t *	datalen,
		const uint16_t *	crc16
	)

Checks the CRC-16 of a data_group.

The CRC is the CRC-16/CCITT (polynomial x^16 + x^12 + x^5 + 1, initial value 0), calculated over the whole data_group, from the data_group_id to the last data byte (ARIB STD-B24, Volume 3, 9.2).

Parameters

data	Start of the `data_group` (the `data_group_id` byte).
datalen	Number of bytes of `data` covered by the CRC (5 of header + `data_group_size`).
crc16	CRC read from the packet.

Returns: TRUE if the CRC matches.

◆ caption_data_load()

bool caption_data_load	(	const PacketPES_t *	pes,
		CaptionData_t *	caption
	)

Loads the data_group of a PES and checks the CRC.

Stuffing bytes after the data_group are ignored.