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