drivers/media/test-drivers/vidtv/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 */
  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