// 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 multiplexer logic for TS packets from different
* elementary streams
*
* Loosely based on libavcodec/mpegtsenc.c
*
* Copyright (C) 2020 Daniel W. S. Almeida
*/
#include <linux/delay.h>
#include <linux/dev_printk.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/math64.h>
#include <linux/ratelimit.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/vmalloc.h>
#include "vidtv_channel.h"
#include "vidtv_common.h"
#include "vidtv_encoder.h"
#include "vidtv_mux.h"
#include "vidtv_pes.h"
#include "vidtv_psi.h"
#include "vidtv_ts.h"
static struct vidtv_mux_pid_ctx
*vidtv_mux_get_pid_ctx(struct vidtv_mux *m, u16 pid)
{
struct vidtv_mux_pid_ctx *ctx;
hash_for_each_possible(m->pid_ctx, ctx, h, pid)
if (ctx->pid == pid)
return ctx;
return NULL;
}
static struct vidtv_mux_pid_ctx
*vidtv_mux_create_pid_ctx_once(struct vidtv_mux *m, u16 pid)
{
struct vidtv_mux_pid_ctx *ctx;
ctx = vidtv_mux_get_pid_ctx(m, pid);
if (ctx)
return ctx;
ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
if (!ctx)
return NULL;
ctx->pid = pid;
ctx->cc = 0;
hash_add(m->pid_ctx, &ctx->h, pid);
return ctx;
}
static void vidtv_mux_pid_ctx_destroy(struct vidtv_mux *m)
{
struct vidtv_mux_pid_ctx *ctx;
struct hlist_node *tmp;
int bkt;
hash_for_each_safe(m->pid_ctx, bkt, tmp, ctx, h) {
hash_del(&ctx->h);
kfree(ctx);
}
}
static int vidtv_mux_pid_ctx_init(struct vidtv_mux *m)
{
struct vidtv_psi_table_pat_program *p = m->si.pat->program;
u16 pid;
hash_init(m->pid_ctx);
/* push the pcr pid ctx */
if (!vidtv_mux_create_pid_ctx_once(m, m->pcr_pid))
return -ENOMEM;
/* push the NULL packet pid ctx */
if (!vidtv_mux_create_pid_ctx_once(m, TS_NULL_PACKET_PID))
goto free;
/* push the PAT pid ctx */
if (!vidtv_mux_create_pid_ctx_once(m, VIDTV_PAT_PID))
goto free;
/* push the SDT pid ctx */
if (!vidtv_mux_create_pid_ctx_once(m, VIDTV_SDT_PID))
goto free;
/* push the NIT pid ctx */
if (!vidtv_mux_create_pid_ctx_once(m, VIDTV_NIT_PID))
goto free;
/* push the EIT pid ctx */
if (!vidtv_mux_create_pid_ctx_once(m, VIDTV_EIT_PID))
goto free;
/* add a ctx for all PMT sections */
while (p) {
pid = vidtv_psi_get_pat_program_pid(p);
vidtv_mux_create_pid_ctx_once(m, pid);
p = p->next;
}
return 0;
free:
vidtv_mux_pid_ctx_destroy(m);
return -ENOMEM;
}
static void vidtv_mux_update_clk(struct vidtv_mux *m)
{
/* call this at every thread iteration */
u64 elapsed_time;
m->timing.past_jiffies = m->timing.current_jiffies;
m->timing.current_jiffies = get_jiffies_64();
elapsed_time = jiffies_to_usecs(m->timing.current_jiffies -
m->timing.past_jiffies);
/* update the 27Mhz clock proportionally to the elapsed time */
m->timing.clk += (CLOCK_UNIT_27MHZ / USEC_PER_SEC) * elapsed_time;
}
static u32 vidtv_mux_push_si(struct vidtv_mux *m)
{
struct vidtv_psi_pat_write_args pat_args = {
.buf = m->mux_buf,
.buf_sz = m->mux_buf_sz,
.pat = m->si.pat,
};
struct vidtv_psi_pmt_write_args pmt_args = {
.buf = m->mux_buf,
.buf_sz = m->mux_buf_sz,
.pcr_pid = m->pcr_pid,
};
struct vidtv_psi_sdt_write_args sdt_args = {
.buf = m->mux_buf,
.buf_sz = m->mux_buf_sz,
.sdt = m->si.sdt,
};
struct vidtv_psi_nit_write_args nit_args = {
.buf = m->mux_buf,
.buf_sz = m->mux_buf_sz,
.nit = m->si.nit,
};
struct vidtv_psi_eit_write_args eit_args = {
.buf = m->mux_buf,
.buf_sz = m->mux_buf_sz,
.eit = m->si.eit,
};
u32 initial_offset = m->mux_buf_offset;
struct vidtv_mux_pid_ctx *pat_ctx;
struct vidtv_mux_pid_ctx *pmt_ctx;
struct vidtv_mux_pid_ctx *sdt_ctx;
struct vidtv_mux_pid_ctx *nit_ctx;
struct vidtv_mux_pid_ctx *eit_ctx;
u32 nbytes;
u16 pmt_pid;
u32 i;
pat_ctx = vidtv_mux_get_pid_ctx(m, VIDTV_PAT_PID);
sdt_ctx = vidtv_mux_get_pid_ctx(m, VIDTV_SDT_PID);
nit_ctx = vidtv_mux_get_pid_ctx(m, VIDTV_NIT_PID);
eit_ctx = vidtv_mux_get_pid_ctx(m, VIDTV_EIT_PID);
pat_args.offset = m->mux_buf_offset;
pat_args.continuity_counter = &pat_ctx->cc;
m->mux_buf_offset += vidtv_psi_pat_write_into(&pat_args);
for (i = 0; i < m->si.pat->num_pmt; ++i) {
pmt_pid = vidtv_psi_pmt_get_pid(m->si.pmt_secs[i],
m->si.pat);
if (pmt_pid > TS_LAST_VALID_PID) {
dev_warn_ratelimited(m->dev,
"PID: %d not found\n", pmt_pid);
continue;
}
pmt_ctx = vidtv_mux_get_pid_ctx(m, pmt_pid);
pmt_args.offset = m->mux_buf_offset;
pmt_args.pmt = m->si.pmt_secs[i];
pmt_args.pid = pmt_pid;
pmt_args.continuity_counter = &pmt_ctx->cc;
/* write each section into buffer */
m->mux_buf_offset += vidtv_psi_pmt_write_into(&pmt_args);
}
sdt_args.offset = m->mux_buf_offset;
sdt_args.continuity_counter = &sdt_ctx->cc;
m->mux_buf_offset += vidtv_psi_sdt_write_into(&sdt_args);
nit_args.offset = m->mux_buf_offset;
nit_args.continuity_counter = &nit_ctx->cc;
m->mux_buf_offset += vidtv_psi_nit_write_into(&nit_args);
eit_args.offset = m->mux_buf_offset;
eit_args.continuity_counter = &eit_ctx->cc;
m->mux_buf_offset += vidtv_psi_eit_write_into(&eit_args);
nbytes = m->mux_buf_offset - initial_offset;
m->num_streamed_si++;
return nbytes;
}
static u32 vidtv_mux_push_pcr(struct vidtv_mux *m)
{
struct pcr_write_args args = {};
struct vidtv_mux_pid_ctx *ctx;
u32 nbytes = 0;
ctx = vidtv_mux_get_pid_ctx(m, m->pcr_pid);
args.dest_buf = m->mux_buf;
args.pid = m->pcr_pid;
args.buf_sz = m->mux_buf_sz;
args.continuity_counter = &ctx->cc;
/* the 27Mhz clock will feed both parts of the PCR bitfield */
args.pcr = m->timing.clk;
nbytes += vidtv_ts_pcr_write_into(args);
m->mux_buf_offset += nbytes;
m->num_streamed_pcr++;
return nbytes;
}
static bool vidtv_mux_should_push_pcr(struct vidtv_mux *m)
{
u64 next_pcr_at;
if (m->num_streamed_pcr == 0)
return true;
next_pcr_at = m->timing.start_jiffies +
usecs_to_jiffies(m->num_streamed_pcr *
m->timing.pcr_period_usecs);
return time_after64(m->timing.current_jiffies, next_pcr_at);
}
static bool vidtv_mux_should_push_si(struct vidtv_mux *m)
{
u64 next_si_at;
if (m->num_streamed_si == 0)
return true;
next_si_at = m->timing.start_jiffies +
usecs_to_jiffies(m->num_streamed_si *
m->timing.si_period_usecs);
return time_after64(m->timing.current_jiffies, next_si_at);
}
static u32 vidtv_mux_packetize_access_units(struct vidtv_mux *m,
struct vidtv_encoder *e)
{
struct pes_write_args args = {
.dest_buf = m->mux_buf,
.dest_buf_sz = m->mux_buf_sz,
.pid = be16_to_cpu(e->es_pid),
.encoder_id = e->id,
.stream_id = be16_to_cpu(e->stream_id),
.send_pts = true, /* forbidden value '01'... */
.send_dts = false, /* ...for PTS_DTS flags */
};
struct vidtv_access_unit *au = e->access_units;
u32 initial_offset = m->mux_buf_offset;
struct vidtv_mux_pid_ctx *pid_ctx;
u32 nbytes = 0;
u8 *buf = NULL;
/* see SMPTE 302M clause 6.4 */
if (args.encoder_id == S302M) {
args.send_dts = false;
args.send_pts = true;
}
pid_ctx = vidtv_mux_create_pid_ctx_once(m, be16_to_cpu(e->es_pid));
args.continuity_counter = &pid_ctx->cc;
while (au) {
buf = e->encoder_buf + au->offset;
args.from = buf;
args.access_unit_len = au->nbytes;
args.dest_offset = m->mux_buf_offset;
args.pts = au->pts;
args.pcr = m->timing.clk;
m->mux_buf_offset += vidtv_pes_write_into(&args);
au = au->next;
}
/*
* clear the encoder state once the ES data has been written to the mux
* buffer
*/
e->clear(e);
nbytes = m->mux_buf_offset - initial_offset;
return nbytes;
}
static u32 vidtv_mux_poll_encoders(struct vidtv_mux *m)
{
struct vidtv_channel *cur_chnl = m->channels;
struct vidtv_encoder *e = NULL;
u32 nbytes = 0;
u32 au_nbytes;
while (cur_chnl) {
e = cur_chnl->encoders;
while (e) {
e->encode(e);
/* get the TS packets into the mux buffer */
au_nbytes = vidtv_mux_packetize_access_units(m, e);
nbytes += au_nbytes;
m->mux_buf_offset += au_nbytes;
/* grab next encoder */
e = e->next;
}
/* grab the next channel */
cur_chnl = cur_chnl->next;
}
return nbytes;
}
static u32 vidtv_mux_pad_with_nulls(struct vidtv_mux *m, u32 npkts)
{
struct null_packet_write_args args = {
.dest_buf = m->mux_buf,
.buf_sz = m->mux_buf_sz,
.dest_offset = m->mux_buf_offset,
};
u32 initial_offset = m->mux_buf_offset;
struct vidtv_mux_pid_ctx *ctx;
u32 nbytes;
u32 i;
ctx = vidtv_mux_get_pid_ctx(m, TS_NULL_PACKET_PID);
args.continuity_counter = &ctx->cc;
for (i = 0; i < npkts; ++i) {
m->mux_buf_offset += vidtv_ts_null_write_into(args);
args.dest_offset = m->mux_buf_offset;
}
nbytes = m->mux_buf_offset - initial_offset;
/* sanity check */
if (nbytes != npkts * TS_PACKET_LEN)
dev_err_ratelimited(m->dev, "%d != %d\n",
nbytes, npkts * TS_PACKET_LEN);
return nbytes;
}
static void vidtv_mux_clear(struct vidtv_mux *m)
{
/* clear the packets currently in the mux */
memset(m->mux_buf, 0, m->mux_buf_sz * sizeof(*m->mux_buf));
/* point to the beginning of the buffer again */
m->mux_buf_offset = 0;
}
#define ERR_RATE 10000000
static void vidtv_mux_tick(struct work_struct *work)
{
struct vidtv_mux *m = container_of(work,
struct vidtv_mux,
mpeg_thread);
struct dtv_frontend_properties *c = &m->fe->dtv_property_cache;
u32 tot_bits = 0;
u32 nbytes;
u32 npkts;
while (m->streaming) {
nbytes = 0;
vidtv_mux_update_clk(m);
if (vidtv_mux_should_push_pcr(m))
nbytes += vidtv_mux_push_pcr(m);
if (vidtv_mux_should_push_si(m))
nbytes += vidtv_mux_push_si(m);
nbytes += vidtv_mux_poll_encoders(m);
nbytes += vidtv_mux_pad_with_nulls(m, 256);
npkts = nbytes / TS_PACKET_LEN;
/* if the buffer is not aligned there is a bug somewhere */
if (nbytes % TS_PACKET_LEN)
dev_err_ratelimited(m->dev, "Misaligned buffer\n");
if (m->on_new_packets_available_cb)
m->on_new_packets_available_cb(m->priv,
m->mux_buf,
npkts);
vidtv_mux_clear(m);
/*
* Update bytes and packet counts at DVBv5 stats
*
* For now, both pre and post bit counts are identical,
* but post BER count can be lower than pre BER, if the error
* correction logic discards packages.
*/
c->pre_bit_count.stat[0].uvalue = nbytes * 8;
c->post_bit_count.stat[0].uvalue = nbytes * 8;
c->block_count.stat[0].uvalue += npkts;
/*
* Even without any visible errors for the user, the pre-BER
* stats usually have an error range up to 1E-6. So,
* add some random error increment count to it.
*
* Please notice that this is a poor guy's implementation,
* as it will produce one corrected bit error every time
* ceil(total bytes / ERR_RATE) is incremented, without
* any sort of (pseudo-)randomness.
*/
tot_bits += nbytes * 8;
if (tot_bits > ERR_RATE) {
c->pre_bit_error.stat[0].uvalue++;
tot_bits -= ERR_RATE;
}
usleep_range(VIDTV_SLEEP_USECS, VIDTV_MAX_SLEEP_USECS);
}
}
void vidtv_mux_start_thread(struct vidtv_mux *m)
{
if (m->streaming) {
dev_warn_ratelimited(m->dev, "Already streaming. Skipping.\n");
return;
}
m->streaming = true;
m->timing.start_jiffies = get_jiffies_64();
schedule_work(&m->mpeg_thread);
}
void vidtv_mux_stop_thread(struct vidtv_mux *m)
{
if (m->streaming) {
m->streaming = false; /* thread will quit */
cancel_work_sync(&m->mpeg_thread);
}
}
struct vidtv_mux *vidtv_mux_init(struct dvb_frontend *fe,
struct device *dev,
struct vidtv_mux_init_args *args)
{
struct vidtv_mux *m;
m = kzalloc(sizeof(*m), GFP_KERNEL);
if (!m)
return NULL;
m->dev = dev;
m->fe = fe;
m->timing.pcr_period_usecs = args->pcr_period_usecs;
m->timing.si_period_usecs = args->si_period_usecs;
m->mux_rate_kbytes_sec = args->mux_rate_kbytes_sec;
m->on_new_packets_available_cb = args->on_new_packets_available_cb;
m->mux_buf = vzalloc(args->mux_buf_sz);
if (!m->mux_buf)
goto free_mux;
m->mux_buf_sz = args->mux_buf_sz;
m->pcr_pid = args->pcr_pid;
m->transport_stream_id = args->transport_stream_id;
m->priv = args->priv;
m->network_id = args->network_id;
m->network_name = kstrdup(args->network_name, GFP_KERNEL);
if (!m->network_name)
goto free_mux_buf;
m->timing.current_jiffies = get_jiffies_64();
if (args->channels)
m->channels = args->channels;
else
if (vidtv_channels_init(m) < 0)
goto free_mux_network_name;
/* will alloc data for pmt_sections after initializing pat */
if (vidtv_channel_si_init(m) < 0)
goto free_channels;
INIT_WORK(&m->mpeg_thread, vidtv_mux_tick);
if (vidtv_mux_pid_ctx_init(m) < 0)
goto free_channel_si;
return m;
free_channel_si:
vidtv_channel_si_destroy(m);
free_channels:
vidtv_channels_destroy(m);
free_mux_network_name:
kfree(m->network_name);
free_mux_buf:
vfree(m->mux_buf);
free_mux:
kfree(m);
return NULL;
}
void vidtv_mux_destroy(struct vidtv_mux *m)
{
vidtv_mux_stop_thread(m);
vidtv_mux_pid_ctx_destroy(m);
vidtv_channel_si_destroy(m);
vidtv_channels_destroy(m);
kfree(m->network_name);
vfree(m->mux_buf);
kfree(m);
}
Codebase Browser
linux