vidtv_ts.h

  1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 * The Virtual DVB test driver serves as a reference DVB driver and helps
  4 * validate the existing APIs in the media subsystem. It can also aid
  5 * developers working on userspace applications.
  6 *
  7 * Copyright (C) 2020 Daniel W. S. Almeida
  8 */
  9
 10#ifndef VIDTV_TS_H
 11#define VIDTV_TS_H
 12
 13#include <linux/types.h>
 14
 15#define TS_SYNC_BYTE 0x47
 16#define TS_PACKET_LEN 188
 17#define TS_PAYLOAD_LEN 184
 18#define TS_NULL_PACKET_PID 0x1fff
 19#define TS_CC_MAX_VAL 0x0f /* 4 bits */
 20#define TS_LAST_VALID_PID 8191
 21#define TS_FILL_BYTE 0xff /* the byte used in packet stuffing */
 22
 23struct vidtv_mpeg_ts_adaption {
 24	u8 length;
 25	struct {
 26		u8 extension:1;
 27		u8 private_data:1;
 28		u8 splicing_point:1;
 29		u8 OPCR:1;
 30		u8 PCR:1;
 31		u8 priority:1;
 32		u8 random_access:1;
 33		u8 discontinued:1;
 34	} __packed;
 35	u8 data[];
 36} __packed;
 37
 38struct vidtv_mpeg_ts {
 39	u8 sync_byte;
 40	__be16 bitfield; /* tei: 1, payload_start:1 priority: 1, pid:13 */
 41	struct {
 42		u8 continuity_counter:4;
 43		u8 payload:1;
 44		u8 adaptation_field:1;
 45		u8 scrambling:2;
 46	} __packed;
 47} __packed;
 48
 49/**
 50 * struct pcr_write_args - Arguments for the pcr_write_into function.
 51 * @dest_buf: The buffer to write into.
 52 * @dest_offset: The byte offset into the buffer.
 53 * @pid: The TS PID for the PCR packets.
 54 * @buf_sz: The size of the buffer in bytes.
 55 * @continuity_counter: The TS continuity_counter.
 56 * @pcr: A sample from the system clock.
 57 */
 58struct pcr_write_args {
 59	void *dest_buf;
 60	u32 dest_offset;
 61	u16 pid;
 62	u32 buf_sz;
 63	u8 *continuity_counter;
 64	u64 pcr;
 65};
 66
 67/**
 68 * struct null_packet_write_args - Arguments for the null_write_into function
 69 * @dest_buf: The buffer to write into.
 70 * @dest_offset: The byte offset into the buffer.
 71 * @buf_sz: The size of the buffer in bytes.
 72 * @continuity_counter: The TS continuity_counter.
 73 */
 74struct null_packet_write_args {
 75	void *dest_buf;
 76	u32 dest_offset;
 77	u32 buf_sz;
 78	u8 *continuity_counter;
 79};
 80
 81/* Increment the continuity counter */
 82void vidtv_ts_inc_cc(u8 *continuity_counter);
 83
 84/**
 85 * vidtv_ts_null_write_into - Write a TS null packet into a buffer.
 86 * @args: the arguments to use when writing.
 87 *
 88 * This function will write a null packet into a buffer. This is usually used to
 89 * pad TS streams.
 90 *
 91 * Return: The number of bytes written into the buffer.
 92 */
 93u32 vidtv_ts_null_write_into(const struct null_packet_write_args *args);
 94
 95/**
 96 * vidtv_ts_pcr_write_into - Write a PCR  packet into a buffer.
 97 * @args: the arguments to use when writing.
 98 *
 99 * This function will write a PCR packet into a buffer. This is used to
100 * synchronize the clocks between encoders and decoders.
101 *
102 * Return: The number of bytes written into the buffer.
103 */
104u32 vidtv_ts_pcr_write_into(const struct pcr_write_args *args);
105
106#endif //VIDTV_TS_H