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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Vidtv serves as a reference DVB driver and helps validate the existing APIs
4 * in the media subsystem. It can also aid developers working on userspace
5 * applications.
6 *
7 * This file contains the logic to translate the ES data for one access unit
8 * from an encoder into MPEG TS packets. It does so by first encapsulating it
9 * with a PES header and then splitting it into TS packets.
10 *
11 * Copyright (C) 2020 Daniel W. S. Almeida
12 */
13
14#ifndef VIDTV_PES_H
15#define VIDTV_PES_H
16
17#include <linux/types.h>
18
19#include "vidtv_common.h"
20
21#define PES_MAX_LEN 65536 /* Set 'length' to 0 if greater. Only possible for video. */
22#define PES_START_CODE_PREFIX 0x001 /* 00 00 01 */
23
24/* Used when sending PTS, but not DTS */
25struct vidtv_pes_optional_pts {
26 u8 pts1;
27 __be16 pts2;
28 __be16 pts3;
29} __packed;
30
31/* Used when sending both PTS and DTS */
32struct vidtv_pes_optional_pts_dts {
33 u8 pts1;
34 __be16 pts2;
35 __be16 pts3;
36
37 u8 dts1;
38 __be16 dts2;
39 __be16 dts3;
40} __packed;
41
42/* PES optional flags */
43struct vidtv_pes_optional {
44 /*
45 * These flags show which components are actually
46 * present in the "optional fields" in the optional PES
47 * header and which are not
48 *
49 * u16 two:2; //0x2
50 * u16 PES_scrambling_control:2;
51 * u16 PES_priority:1;
52 * u16 data_alignment_indicator:1; // unused
53 * u16 copyright:1;
54 * u16 original_or_copy:1;
55 * u16 PTS_DTS:2;
56 * u16 ESCR:1;
57 * u16 ES_rate:1;
58 * u16 DSM_trick_mode:1;
59 * u16 additional_copy_info:1;
60 * u16 PES_CRC:1;
61 * u16 PES_extension:1;
62 */
63 __be16 bitfield;
64 u8 length;
65} __packed;
66
67/* The PES header */
68struct vidtv_mpeg_pes {
69 __be32 bitfield; /* packet_start_code_prefix:24, stream_id: 8 */
70 /* after this field until the end of the PES data payload */
71 __be16 length;
72 struct vidtv_pes_optional optional[];
73} __packed;
74
75/**
76 * struct pes_header_write_args - Arguments to write a PES header.
77 * @dest_buf: The buffer to write into.
78 * @dest_offset: where to start writing in the dest_buffer.
79 * @dest_buf_sz: The size of the dest_buffer
80 * @encoder_id: Encoder id (see vidtv_encoder.h)
81 * @send_pts: Should we send PTS?
82 * @pts: PTS value to send.
83 * @send_dts: Should we send DTS?
84 * @dts: DTS value to send.
85 * @stream_id: The stream id to use. Ex: Audio streams (0xc0-0xdf), Video
86 * streams (0xe0-0xef).
87 * @n_pes_h_s_bytes: Padding bytes. Might be used by an encoder if needed, gets
88 * discarded by the decoder.
89 * @access_unit_len: The size of _one_ access unit (with any headers it might need)
90 */
91struct pes_header_write_args {
92 void *dest_buf;
93 u32 dest_offset;
94 u32 dest_buf_sz;
95 u32 encoder_id;
96
97 bool send_pts;
98 u64 pts;
99
100 bool send_dts;
101 u64 dts;
102
103 u16 stream_id;
104 /* might be used by an encoder if needed, gets discarded by decoder */
105 u32 n_pes_h_s_bytes;
106 u32 access_unit_len;
107};
108
109/**
110 * struct pes_ts_header_write_args - Arguments to write a TS header.
111 * @dest_buf: The buffer to write into.
112 * @dest_offset: where to start writing in the dest_buffer.
113 * @dest_buf_sz: The size of the dest_buffer
114 * @pid: The PID to use for the TS packets.
115 * @continuity_counter: Incremented on every new TS packet.
116 * @wrote_pes_header: Flag to indicate that the PES header was written
117 * @n_stuffing_bytes: Padding bytes. Might be used by an encoder if needed, gets
118 * discarded by the decoder.
119 * @pcr: counter driven by a 27Mhz clock.
120 */
121struct pes_ts_header_write_args {
122 void *dest_buf;
123 u32 dest_offset;
124 u32 dest_buf_sz;
125 u16 pid;
126 u8 *continuity_counter;
127 bool wrote_pes_header;
128 u32 n_stuffing_bytes;
129 u64 pcr;
130};
131
132/**
133 * struct pes_write_args - Arguments for the packetizer.
134 * @dest_buf: The buffer to write into.
135 * @from: A pointer to the encoder buffer containing one access unit.
136 * @access_unit_len: The size of _one_ access unit (with any headers it might need)
137 * @dest_offset: where to start writing in the dest_buffer.
138 * @dest_buf_sz: The size of the dest_buffer
139 * @pid: The PID to use for the TS packets.
140 * @encoder_id: Encoder id (see vidtv_encoder.h)
141 * @continuity_counter: Incremented on every new TS packet.
142 * @stream_id: The stream id to use. Ex: Audio streams (0xc0-0xdf), Video
143 * streams (0xe0-0xef).
144 * @send_pts: Should we send PTS?
145 * @pts: PTS value to send.
146 * @send_dts: Should we send DTS?
147 * @dts: DTS value to send.
148 * @n_pes_h_s_bytes: Padding bytes. Might be used by an encoder if needed, gets
149 * discarded by the decoder.
150 * @pcr: counter driven by a 27Mhz clock.
151 */
152struct pes_write_args {
153 void *dest_buf;
154 void *from;
155 u32 access_unit_len;
156
157 u32 dest_offset;
158 u32 dest_buf_sz;
159 u16 pid;
160
161 u32 encoder_id;
162
163 u8 *continuity_counter;
164
165 u16 stream_id;
166
167 bool send_pts;
168 u64 pts;
169
170 bool send_dts;
171 u64 dts;
172
173 u32 n_pes_h_s_bytes;
174 u64 pcr;
175};
176
177/**
178 * vidtv_pes_write_into - Write a PES packet as MPEG-TS packets into a buffer.
179 * @args: The args to use when writing
180 *
181 * This function translate the ES data for one access unit
182 * from an encoder into MPEG TS packets. It does so by first encapsulating it
183 * with a PES header and then splitting it into TS packets.
184 *
185 * The data is then written into the buffer pointed to by 'args.buf'
186 *
187 * Return: The number of bytes written into the buffer. This is usually NOT
188 * equal to the size of the access unit, since we need space for PES headers, TS headers
189 * and padding bytes, if any.
190 */
191u32 vidtv_pes_write_into(struct pes_write_args *args);
192
193#endif // VIDTV_PES_H
1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Vidtv serves as a reference DVB driver and helps validate the existing APIs
4 * in the media subsystem. It can also aid developers working on userspace
5 * applications.
6 *
7 * This file contains the logic to translate the ES data for one access unit
8 * from an encoder into MPEG TS packets. It does so by first encapsulating it
9 * with a PES header and then splitting it into TS packets.
10 *
11 * Copyright (C) 2020 Daniel W. S. Almeida
12 */
13
14#ifndef VIDTV_PES_H
15#define VIDTV_PES_H
16
17#include <linux/types.h>
18
19#include "vidtv_common.h"
20
21#define PES_MAX_LEN 65536 /* Set 'length' to 0 if greater. Only possible for video. */
22#define PES_START_CODE_PREFIX 0x001 /* 00 00 01 */
23
24/* Used when sending PTS, but not DTS */
25struct vidtv_pes_optional_pts {
26 u8 pts1;
27 __be16 pts2;
28 __be16 pts3;
29} __packed;
30
31/* Used when sending both PTS and DTS */
32struct vidtv_pes_optional_pts_dts {
33 u8 pts1;
34 __be16 pts2;
35 __be16 pts3;
36
37 u8 dts1;
38 __be16 dts2;
39 __be16 dts3;
40} __packed;
41
42/* PES optional flags */
43struct vidtv_pes_optional {
44 /*
45 * These flags show which components are actually
46 * present in the "optional fields" in the optional PES
47 * header and which are not
48 *
49 * u16 two:2; //0x2
50 * u16 PES_scrambling_control:2;
51 * u16 PES_priority:1;
52 * u16 data_alignment_indicator:1; // unused
53 * u16 copyright:1;
54 * u16 original_or_copy:1;
55 * u16 PTS_DTS:2;
56 * u16 ESCR:1;
57 * u16 ES_rate:1;
58 * u16 DSM_trick_mode:1;
59 * u16 additional_copy_info:1;
60 * u16 PES_CRC:1;
61 * u16 PES_extension:1;
62 */
63 __be16 bitfield;
64 u8 length;
65} __packed;
66
67/* The PES header */
68struct vidtv_mpeg_pes {
69 __be32 bitfield; /* packet_start_code_prefix:24, stream_id: 8 */
70 /* after this field until the end of the PES data payload */
71 __be16 length;
72 struct vidtv_pes_optional optional[];
73} __packed;
74
75/**
76 * struct pes_header_write_args - Arguments to write a PES header.
77 * @dest_buf: The buffer to write into.
78 * @dest_offset: where to start writing in the dest_buffer.
79 * @dest_buf_sz: The size of the dest_buffer
80 * @encoder_id: Encoder id (see vidtv_encoder.h)
81 * @send_pts: Should we send PTS?
82 * @pts: PTS value to send.
83 * @send_dts: Should we send DTS?
84 * @dts: DTS value to send.
85 * @stream_id: The stream id to use. Ex: Audio streams (0xc0-0xdf), Video
86 * streams (0xe0-0xef).
87 * @n_pes_h_s_bytes: Padding bytes. Might be used by an encoder if needed, gets
88 * discarded by the decoder.
89 * @access_unit_len: The size of _one_ access unit (with any headers it might need)
90 */
91struct pes_header_write_args {
92 void *dest_buf;
93 u32 dest_offset;
94 u32 dest_buf_sz;
95 u32 encoder_id;
96
97 bool send_pts;
98 u64 pts;
99
100 bool send_dts;
101 u64 dts;
102
103 u16 stream_id;
104 /* might be used by an encoder if needed, gets discarded by decoder */
105 u32 n_pes_h_s_bytes;
106 u32 access_unit_len;
107};
108
109/**
110 * struct pes_ts_header_write_args - Arguments to write a TS header.
111 * @dest_buf: The buffer to write into.
112 * @dest_offset: where to start writing in the dest_buffer.
113 * @dest_buf_sz: The size of the dest_buffer
114 * @pid: The PID to use for the TS packets.
115 * @continuity_counter: Incremented on every new TS packet.
116 * @wrote_pes_header: Flag to indicate that the PES header was written
117 * @n_stuffing_bytes: Padding bytes. Might be used by an encoder if needed, gets
118 * discarded by the decoder.
119 * @pcr: counter driven by a 27Mhz clock.
120 */
121struct pes_ts_header_write_args {
122 void *dest_buf;
123 u32 dest_offset;
124 u32 dest_buf_sz;
125 u16 pid;
126 u8 *continuity_counter;
127 bool wrote_pes_header;
128 u32 n_stuffing_bytes;
129 u64 pcr;
130};
131
132/**
133 * struct pes_write_args - Arguments for the packetizer.
134 * @dest_buf: The buffer to write into.
135 * @from: A pointer to the encoder buffer containing one access unit.
136 * @access_unit_len: The size of _one_ access unit (with any headers it might need)
137 * @dest_offset: where to start writing in the dest_buffer.
138 * @dest_buf_sz: The size of the dest_buffer
139 * @pid: The PID to use for the TS packets.
140 * @encoder_id: Encoder id (see vidtv_encoder.h)
141 * @continuity_counter: Incremented on every new TS packet.
142 * @stream_id: The stream id to use. Ex: Audio streams (0xc0-0xdf), Video
143 * streams (0xe0-0xef).
144 * @send_pts: Should we send PTS?
145 * @pts: PTS value to send.
146 * @send_dts: Should we send DTS?
147 * @dts: DTS value to send.
148 * @n_pes_h_s_bytes: Padding bytes. Might be used by an encoder if needed, gets
149 * discarded by the decoder.
150 * @pcr: counter driven by a 27Mhz clock.
151 */
152struct pes_write_args {
153 void *dest_buf;
154 void *from;
155 u32 access_unit_len;
156
157 u32 dest_offset;
158 u32 dest_buf_sz;
159 u16 pid;
160
161 u32 encoder_id;
162
163 u8 *continuity_counter;
164
165 u16 stream_id;
166
167 bool send_pts;
168 u64 pts;
169
170 bool send_dts;
171 u64 dts;
172
173 u32 n_pes_h_s_bytes;
174 u64 pcr;
175};
176
177/**
178 * vidtv_pes_write_into - Write a PES packet as MPEG-TS packets into a buffer.
179 * @args: The args to use when writing
180 *
181 * This function translate the ES data for one access unit
182 * from an encoder into MPEG TS packets. It does so by first encapsulating it
183 * with a PES header and then splitting it into TS packets.
184 *
185 * The data is then written into the buffer pointed to by 'args.buf'
186 *
187 * Return: The number of bytes written into the buffer. This is usually NOT
188 * equal to the size of the access unit, since we need space for PES headers, TS headers
189 * and padding bytes, if any.
190 */
191u32 vidtv_pes_write_into(struct pes_write_args *args);
192
193#endif // VIDTV_PES_H