blob: 6a360a0a3ccfec60f59586715722875b14e59cf6 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/*
* Vidtv serves as a reference DVB driver and helps validate the existing APIs
* in the media subsystem. It can also aid developers working on userspace
* applications.
*
* This file contains the logic to translate the ES data for one access unit
* from an encoder into MPEG TS packets. It does so by first encapsulating it
* with a PES header and then splitting it into TS packets.
*
* Copyright (C) 2020 Daniel W. S. Almeida
*/
#define pr_fmt(fmt) KBUILD_MODNAME ":%s, %d: " fmt, __func__, __LINE__
#include <linux/types.h>
#include <linux/math64.h>
#include <linux/printk.h>
#include <linux/ratelimit.h>
#include "vidtv_pes.h"
#include "vidtv_common.h"
#include "vidtv_encoder.h"
#include "vidtv_ts.h"
#define PRIVATE_STREAM_1_ID 0xbd /* private_stream_1. See SMPTE 302M-2007 p.6 */
#define PES_HEADER_MAX_STUFFING_BYTES 32
#define PES_TS_HEADER_MAX_STUFFING_BYTES 182
static u32 vidtv_pes_op_get_len(bool send_pts, bool send_dts)
{
u32 len = 0;
/* the flags must always be sent */
len += sizeof(struct vidtv_pes_optional);
/* From all optionals, we might send these for now */
if (send_pts && send_dts)
len += sizeof(struct vidtv_pes_optional_pts_dts);
else if (send_pts)
len += sizeof(struct vidtv_pes_optional_pts);
return len;
}
#define SIZE_PCR (6 + sizeof(struct vidtv_mpeg_ts_adaption))
static u32 vidtv_pes_h_get_len(bool send_pts, bool send_dts)
{
u32 len = 0;
/* PES header length notwithstanding stuffing bytes */
len += sizeof(struct vidtv_mpeg_pes);
len += vidtv_pes_op_get_len(send_pts, send_dts);
return len;
}
static u32 vidtv_pes_write_header_stuffing(struct pes_header_write_args *args)
{
/*
* This is a fixed 8-bit value equal to '0xFF' that can be inserted
* by the encoder, for example to meet the requirements of the channel.
* It is discarded by the decoder. No more than 32 stuffing bytes shall
* be present in one PES packet header.
*/
if (args->n_pes_h_s_bytes > PES_HEADER_MAX_STUFFING_BYTES) {
pr_warn_ratelimited("More than %d stuffing bytes in PES packet header\n",
PES_HEADER_MAX_STUFFING_BYTES);
args->n_pes_h_s_bytes = PES_HEADER_MAX_STUFFING_BYTES;
}
return vidtv_memset(args->dest_buf,
args->dest_offset,
args->dest_buf_sz,
TS_FILL_BYTE,
args->n_pes_h_s_bytes);
}
static u32 vidtv_pes_write_pts_dts(struct pes_header_write_args *args)
{
u32 nbytes = 0; /* the number of bytes written by this function */
struct vidtv_pes_optional_pts pts = {};
struct vidtv_pes_optional_pts_dts pts_dts = {};
void *op = NULL;
size_t op_sz = 0;
u64 mask1;
u64 mask2;
u64 mask3;
if (!args->send_pts && args->send_dts)
return 0;
mask1 = GENMASK_ULL(32, 30);
mask2 = GENMASK_ULL(29, 15);
mask3 = GENMASK_ULL(14, 0);
/* see ISO/IEC 13818-1 : 2000 p. 32 */
if (args->send_pts && args->send_dts) {
pts_dts.pts1 = (0x3 << 4) | ((args->pts & mask1) >> 29) | 0x1;
pts_dts.pts2 = cpu_to_be16(((args->pts & mask2) >> 14) | 0x1);
pts_dts.pts3 = cpu_to_be16(((args->pts & mask3) << 1) | 0x1);
pts_dts.dts1 = (0x1 << 4) | ((args->dts & mask1) >> 29) | 0x1;
pts_dts.dts2 = cpu_to_be16(((args->dts & mask2) >> 14) | 0x1);
pts_dts.dts3 = cpu_to_be16(((args->dts & mask3) << 1) | 0x1);
op = &pts_dts;
op_sz = sizeof(pts_dts);
} else if (args->send_pts) {
pts.pts1 = (0x1 << 5) | ((args->pts & mask1) >> 29) | 0x1;
pts.pts2 = cpu_to_be16(((args->pts & mask2) >> 14) | 0x1);
pts.pts3 = cpu_to_be16(((args->pts & mask3) << 1) | 0x1);
op = &pts;
op_sz = sizeof(pts);
}
/* copy PTS/DTS optional */
nbytes += vidtv_memcpy(args->dest_buf,
args->dest_offset + nbytes,
args->dest_buf_sz,
op,
op_sz);
return nbytes;
}
static u32 vidtv_pes_write_h(struct pes_header_write_args *args)
{
u32 nbytes = 0; /* the number of bytes written by this function */
struct vidtv_mpeg_pes pes_header = {};
struct vidtv_pes_optional pes_optional = {};
struct pes_header_write_args pts_dts_args;
u32 stream_id = (args->encoder_id == S302M) ? PRIVATE_STREAM_1_ID : args->stream_id;
u16 pes_opt_bitfield = 0x01 << 15;
pes_header.bitfield = cpu_to_be32((PES_START_CODE_PREFIX << 8) | stream_id);
pes_header.length = cpu_to_be16(vidtv_pes_op_get_len(args->send_pts,
args->send_dts) +
args->access_unit_len);
if (args->send_pts && args->send_dts)
pes_opt_bitfield |= (0x3 << 6);
else if (args->send_pts)
pes_opt_bitfield |= (0x1 << 7);
pes_optional.bitfield = cpu_to_be16(pes_opt_bitfield);
pes_optional.length = vidtv_pes_op_get_len(args->send_pts, args->send_dts) +
args->n_pes_h_s_bytes -
sizeof(struct vidtv_pes_optional);
/* copy header */
nbytes += vidtv_memcpy(args->dest_buf,
args->dest_offset + nbytes,
args->dest_buf_sz,
&pes_header,
sizeof(pes_header));
/* copy optional header bits */
nbytes += vidtv_memcpy(args->dest_buf,
args->dest_offset + nbytes,
args->dest_buf_sz,
&pes_optional,
sizeof(pes_optional));
/* copy the timing information */
pts_dts_args = *args;
pts_dts_args.dest_offset = args->dest_offset + nbytes;
nbytes += vidtv_pes_write_pts_dts(&pts_dts_args);
/* write any PES header stuffing */
nbytes += vidtv_pes_write_header_stuffing(args);
return nbytes;
}
static u32 vidtv_pes_write_pcr_bits(u8 *to, u32 to_offset, u64 pcr)
{
/* Exact same from ffmpeg. PCR is a counter driven by a 27Mhz clock */
u64 div;
u64 rem;
u8 *buf = to + to_offset;
u64 pcr_low;
u64 pcr_high;
div = div64_u64_rem(pcr, 300, &rem);
pcr_low = rem; /* pcr_low = pcr % 300 */
pcr_high = div; /* pcr_high = pcr / 300 */
*buf++ = pcr_high >> 25;
*buf++ = pcr_high >> 17;
*buf++ = pcr_high >> 9;
*buf++ = pcr_high >> 1;
*buf++ = pcr_high << 7 | pcr_low >> 8 | 0x7e;
*buf++ = pcr_low;
return 6;
}
static u32 vidtv_pes_write_stuffing(struct pes_ts_header_write_args *args,
u32 dest_offset, bool need_pcr,
u64 *last_pcr)
{
struct vidtv_mpeg_ts_adaption ts_adap = {};
int stuff_nbytes;
u32 nbytes = 0;
if (!args->n_stuffing_bytes)
return 0;
ts_adap.random_access = 1;
/* length _immediately_ following 'adaptation_field_length' */
if (need_pcr) {
ts_adap.PCR = 1;
ts_adap.length = SIZE_PCR;
} else {
ts_adap.length = sizeof(ts_adap);
}
stuff_nbytes = args->n_stuffing_bytes - ts_adap.length;
ts_adap.length -= sizeof(ts_adap.length);
if (unlikely(stuff_nbytes < 0))
stuff_nbytes = 0;
ts_adap.length += stuff_nbytes;
/* write the adap after the TS header */
nbytes += vidtv_memcpy(args->dest_buf,
dest_offset + nbytes,
args->dest_buf_sz,
&ts_adap,
sizeof(ts_adap));
/* write the optional PCR */
if (need_pcr) {
nbytes += vidtv_pes_write_pcr_bits(args->dest_buf,
dest_offset + nbytes,
args->pcr);
*last_pcr = args->pcr;
}
/* write the stuffing bytes, if are there anything left */
if (stuff_nbytes)
nbytes += vidtv_memset(args->dest_buf,
dest_offset + nbytes,
args->dest_buf_sz,
TS_FILL_BYTE,
stuff_nbytes);
/*
* The n_stuffing_bytes contain a pre-calculated value of
* the amount of data that this function would read, made from
* vidtv_pes_h_get_len(). If something went wrong, print a warning
*/
if (nbytes != args->n_stuffing_bytes)
pr_warn_ratelimited("write size was %d, expected %d\n",
nbytes, args->n_stuffing_bytes);
return nbytes;
}
static u32 vidtv_pes_write_ts_h(struct pes_ts_header_write_args args,
bool need_pcr, u64 *last_pcr)
{
/* number of bytes written by this function */
u32 nbytes = 0;
struct vidtv_mpeg_ts ts_header = {};
u16 payload_start = !args.wrote_pes_header;
ts_header.sync_byte = TS_SYNC_BYTE;
ts_header.bitfield = cpu_to_be16((payload_start << 14) | args.pid);
ts_header.scrambling = 0;
ts_header.adaptation_field = (args.n_stuffing_bytes) > 0;
ts_header.payload = (args.n_stuffing_bytes) < PES_TS_HEADER_MAX_STUFFING_BYTES;
ts_header.continuity_counter = *args.continuity_counter;
vidtv_ts_inc_cc(args.continuity_counter);
/* write the TS header */
nbytes += vidtv_memcpy(args.dest_buf,
args.dest_offset + nbytes,
args.dest_buf_sz,
&ts_header,
sizeof(ts_header));
/* write stuffing, if any */
nbytes += vidtv_pes_write_stuffing(&args, args.dest_offset + nbytes,
need_pcr, last_pcr);
return nbytes;
}
u32 vidtv_pes_write_into(struct pes_write_args *args)
{
u32 unaligned_bytes = (args->dest_offset % TS_PACKET_LEN);
struct pes_ts_header_write_args ts_header_args = {
.dest_buf = args->dest_buf,
.dest_buf_sz = args->dest_buf_sz,
.pid = args->pid,
.pcr = args->pcr,
.continuity_counter = args->continuity_counter,
};
struct pes_header_write_args pes_header_args = {
.dest_buf = args->dest_buf,
.dest_buf_sz = args->dest_buf_sz,
.encoder_id = args->encoder_id,
.send_pts = args->send_pts,
.pts = args->pts,
.send_dts = args->send_dts,
.dts = args->dts,
.stream_id = args->stream_id,
.n_pes_h_s_bytes = args->n_pes_h_s_bytes,
.access_unit_len = args->access_unit_len,
};
u32 remaining_len = args->access_unit_len;
bool wrote_pes_header = false;
u64 last_pcr = args->pcr;
bool need_pcr = true;
u32 available_space;
u32 payload_size;
u32 stuff_bytes;
u32 nbytes = 0;
if (unaligned_bytes) {
pr_warn_ratelimited("buffer is misaligned, while starting PES\n");
/* forcibly align and hope for the best */
nbytes += vidtv_memset(args->dest_buf,
args->dest_offset + nbytes,
args->dest_buf_sz,
TS_FILL_BYTE,
TS_PACKET_LEN - unaligned_bytes);
}
while (remaining_len) {
available_space = TS_PAYLOAD_LEN;
/*
* The amount of space initially available in the TS packet.
* if this is the beginning of the PES packet, take into account
* the space needed for the TS header _and_ for the PES header
*/
if (!wrote_pes_header)
available_space -= vidtv_pes_h_get_len(args->send_pts,
args->send_dts);
/*
* if the encoder has inserted stuffing bytes in the PES
* header, account for them.
*/
available_space -= args->n_pes_h_s_bytes;
/* Take the extra adaptation into account if need to send PCR */
if (need_pcr) {
available_space -= SIZE_PCR;
stuff_bytes = SIZE_PCR;
} else {
stuff_bytes = 0;
}
/*
* how much of the _actual_ payload should be written in this
* packet.
*/
if (remaining_len >= available_space) {
payload_size = available_space;
} else {
/* Last frame should ensure 188-bytes PS alignment */
payload_size = remaining_len;
stuff_bytes += available_space - payload_size;
/*
* Ensure that the stuff bytes will be within the
* allowed range, decrementing the number of payload
* bytes to write if needed.
*/
if (stuff_bytes > PES_TS_HEADER_MAX_STUFFING_BYTES) {
u32 tmp = stuff_bytes - PES_TS_HEADER_MAX_STUFFING_BYTES;
stuff_bytes = PES_TS_HEADER_MAX_STUFFING_BYTES;
payload_size -= tmp;
}
}
/* write ts header */
ts_header_args.dest_offset = args->dest_offset + nbytes;
ts_header_args.wrote_pes_header = wrote_pes_header;
ts_header_args.n_stuffing_bytes = stuff_bytes;
nbytes += vidtv_pes_write_ts_h(ts_header_args, need_pcr,
&last_pcr);
need_pcr = false;
if (!wrote_pes_header) {
/* write the PES header only once */
pes_header_args.dest_offset = args->dest_offset +
nbytes;
nbytes += vidtv_pes_write_h(&pes_header_args);
wrote_pes_header = true;
}
/* write as much of the payload as we possibly can */
nbytes += vidtv_memcpy(args->dest_buf,
args->dest_offset + nbytes,
args->dest_buf_sz,
args->from,
payload_size);
args->from += payload_size;
remaining_len -= payload_size;
}
return nbytes;
}