xref: /linux/drivers/media/test-drivers/vidtv/vidtv_pes.h (revision a4eb44a6435d6d8f9e642407a4a06f65eb90ca04)
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 */
25 struct vidtv_pes_optional_pts {
26 	u8 pts1;
27 	__be16 pts2;
28 	__be16 pts3;
29 } __packed;
30 
31 /* Used when sending both PTS and DTS */
32 struct 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 */
43 struct 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 */
68 struct 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  */
91 struct 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  */
121 struct 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  */
152 struct 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  */
191 u32 vidtv_pes_write_into(struct pes_write_args *args);
192 
193 #endif // VIDTV_PES_H
194