/* SPDX-License-Identifier: GPL-2.0 */
/*
* Vidtv serves as a reference DVB driver and helps validate the existing APIs
* in the media subsystem. It can also aid developers working on userspace
* applications.
*
* This file contains the logic to translate the ES data for one access unit
* from an encoder into MPEG TS packets. It does so by first encapsulating it
* with a PES header and then splitting it into TS packets.
*
* Copyright (C) 2020 Daniel W. S. Almeida
*/
#ifndef VIDTV_PES_H
#define VIDTV_PES_H
#include <linux/types.h>
#include "vidtv_common.h"
#define PES_MAX_LEN 65536 /* Set 'length' to 0 if greater. Only possible for video. */
#define PES_START_CODE_PREFIX 0x001 /* 00 00 01 */
/* Used when sending PTS, but not DTS */
struct vidtv_pes_optional_pts {
u8 pts1;
__be16 pts2;
__be16 pts3;
} __packed;
/* Used when sending both PTS and DTS */
struct vidtv_pes_optional_pts_dts {
u8 pts1;
__be16 pts2;
__be16 pts3;
u8 dts1;
__be16 dts2;
__be16 dts3;
} __packed;
/* PES optional flags */
struct vidtv_pes_optional {
/*
* These flags show which components are actually
* present in the "optional fields" in the optional PES
* header and which are not
*
* u16 two:2; //0x2
* u16 PES_scrambling_control:2;
* u16 PES_priority:1;
* u16 data_alignment_indicator:1; // unused
* u16 copyright:1;
* u16 original_or_copy:1;
* u16 PTS_DTS:2;
* u16 ESCR:1;
* u16 ES_rate:1;
* u16 DSM_trick_mode:1;
* u16 additional_copy_info:1;
* u16 PES_CRC:1;
* u16 PES_extension:1;
*/
__be16 bitfield;
u8 length;
} __packed;
/* The PES header */
struct vidtv_mpeg_pes {
__be32 bitfield; /* packet_start_code_prefix:24, stream_id: 8 */
/* after this field until the end of the PES data payload */
__be16 length;
struct vidtv_pes_optional optional[];
} __packed;
/**
* struct pes_header_write_args - Arguments to write a PES header.
* @dest_buf: The buffer to write into.
* @dest_offset: where to start writing in the dest_buffer.
* @dest_buf_sz: The size of the dest_buffer
* @encoder_id: Encoder id (see vidtv_encoder.h)
* @send_pts: Should we send PTS?
* @pts: PTS value to send.
* @send_dts: Should we send DTS?
* @dts: DTS value to send.
* @stream_id: The stream id to use. Ex: Audio streams (0xc0-0xdf), Video
* streams (0xe0-0xef).
* @n_pes_h_s_bytes: Padding bytes. Might be used by an encoder if needed, gets
* discarded by the decoder.
* @access_unit_len: The size of _one_ access unit (with any headers it might need)
*/
struct pes_header_write_args {
void *dest_buf;
u32 dest_offset;
u32 dest_buf_sz;
u32 encoder_id;
bool send_pts;
u64 pts;
bool send_dts;
u64 dts;
u16 stream_id;
/* might be used by an encoder if needed, gets discarded by decoder */
u32 n_pes_h_s_bytes;
u32 access_unit_len;
};
/**
* struct pes_ts_header_write_args - Arguments to write a TS header.
* @dest_buf: The buffer to write into.
* @dest_offset: where to start writing in the dest_buffer.
* @dest_buf_sz: The size of the dest_buffer
* @pid: The PID to use for the TS packets.
* @continuity_counter: Incremented on every new TS packet.
* @wrote_pes_header: Flag to indicate that the PES header was written
* @n_stuffing_bytes: Padding bytes. Might be used by an encoder if needed, gets
* discarded by the decoder.
* @pcr: counter driven by a 27Mhz clock.
*/
struct pes_ts_header_write_args {
void *dest_buf;
u32 dest_offset;
u32 dest_buf_sz;
u16 pid;
u8 *continuity_counter;
bool wrote_pes_header;
u32 n_stuffing_bytes;
u64 pcr;
};
/**
* struct pes_write_args - Arguments for the packetizer.
* @dest_buf: The buffer to write into.
* @from: A pointer to the encoder buffer containing one access unit.
* @access_unit_len: The size of _one_ access unit (with any headers it might need)
* @dest_offset: where to start writing in the dest_buffer.
* @dest_buf_sz: The size of the dest_buffer
* @pid: The PID to use for the TS packets.
* @encoder_id: Encoder id (see vidtv_encoder.h)
* @continuity_counter: Incremented on every new TS packet.
* @stream_id: The stream id to use. Ex: Audio streams (0xc0-0xdf), Video
* streams (0xe0-0xef).
* @send_pts: Should we send PTS?
* @pts: PTS value to send.
* @send_dts: Should we send DTS?
* @dts: DTS value to send.
* @n_pes_h_s_bytes: Padding bytes. Might be used by an encoder if needed, gets
* discarded by the decoder.
* @pcr: counter driven by a 27Mhz clock.
*/
struct pes_write_args {
void *dest_buf;
void *from;
u32 access_unit_len;
u32 dest_offset;
u32 dest_buf_sz;
u16 pid;
u32 encoder_id;
u8 *continuity_counter;
u16 stream_id;
bool send_pts;
u64 pts;
bool send_dts;
u64 dts;
u32 n_pes_h_s_bytes;
u64 pcr;
};
/**
* vidtv_pes_write_into - Write a PES packet as MPEG-TS packets into a buffer.
* @args: The args to use when writing
*
* This function translate the ES data for one access unit
* from an encoder into MPEG TS packets. It does so by first encapsulating it
* with a PES header and then splitting it into TS packets.
*
* The data is then written into the buffer pointed to by 'args.buf'
*
* Return: The number of bytes written into the buffer. This is usually NOT
* equal to the size of the access unit, since we need space for PES headers, TS headers
* and padding bytes, if any.
*/
u32 vidtv_pes_write_into(struct pes_write_args *args);
#endif // VIDTV_PES_H
Codebase Browser
linux