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 { |
92 | void *; |
93 | u32 ; |
94 | u32 ; |
95 | u32 ; |
96 | |
97 | bool ; |
98 | u64 ; |
99 | |
100 | bool ; |
101 | u64 ; |
102 | |
103 | u16 ; |
104 | /* might be used by an encoder if needed, gets discarded by decoder */ |
105 | u32 ; |
106 | u32 ; |
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 { |
122 | void *; |
123 | u32 ; |
124 | u32 ; |
125 | u16 ; |
126 | u8 *; |
127 | bool ; |
128 | u32 ; |
129 | u64 ; |
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 | |