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/* 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 muxer logic for TS packets from different
* elementary streams.
*
* Loosely based on libavcodec/mpegtsenc.c
*
* Copyright (C) 2020 Daniel W. S. Almeida
*/
#ifndef VIDTV_MUX_H
#define VIDTV_MUX_H
#include <linux/types.h>
#include <linux/hashtable.h>
#include <linux/workqueue.h>
#include <media/dvb_frontend.h>
#include "vidtv_psi.h"
/**
* struct vidtv_mux_timing - Timing related information
*
* This is used to decide when PCR or PSI packets should be sent. This will also
* provide storage for the clock, which is used to compute the value for the PCR.
*
* @start_jiffies: The value of 'jiffies' when we started the mux thread.
* @current_jiffies: The value of 'jiffies' for the current iteration.
* @past_jiffies: The value of 'jiffies' for the past iteration.
* @clk: A 27Mhz clock from which we will drive the PCR. Updated proportionally
* on every iteration.
* @pcr_period_usecs: How often we should send PCR packets.
* @si_period_usecs: How often we should send PSI packets.
*/
struct vidtv_mux_timing {
u64 start_jiffies;
u64 current_jiffies;
u64 past_jiffies;
u64 clk;
u64 pcr_period_usecs;
u64 si_period_usecs;
};
/**
* struct vidtv_mux_si - Store the PSI context.
*
* This is used to store the PAT, PMT sections and SDT in use by the muxer.
*
* The muxer acquire these by looking into the hardcoded channels in
* vidtv_channel and then periodically sends the TS packets for them>
*
* @pat: The PAT in use by the muxer.
* @pmt_secs: The PMT sections in use by the muxer. One for each program in the PAT.
* @sdt: The SDT in use by the muxer.
*/
struct vidtv_mux_si {
/* the SI tables */
struct vidtv_psi_table_pat *pat;
struct vidtv_psi_table_pmt **pmt_secs; /* the PMT sections */
struct vidtv_psi_table_sdt *sdt;
};
/**
* struct vidtv_mux_pid_ctx - Store the context for a given TS PID.
* @pid: The TS PID.
* @cc: The continuity counter for this PID. It is incremented on every TS
* pack and it will wrap around at 0xf0. If the decoder notices a sudden jump in
* this counter this will trigger a discontinuity state.
* @h: This is embedded in a hash table, mapping pid -> vidtv_mux_pid_ctx
*/
struct vidtv_mux_pid_ctx {
u16 pid;
u8 cc; /* continuity counter */
struct hlist_node h;
};
/**
* struct vidtv_mux - A muxer abstraction loosely based in libavcodec/mpegtsenc.c
* @mux_rate_kbytes_sec: The bit rate for the TS, in kbytes.
* @timing: Keeps track of timing related information.
* @pid_ctx: A hash table to keep track of per-PID metadata.
* @on_new_packets_available_cb: A callback to inform of new TS packets ready.
* @mux_buf: A pointer to a buffer for this muxer. TS packets are stored there
* and then passed on to the bridge driver.
* @mux_buf_sz: The size for 'mux_buf'.
* @mux_buf_offset: The current offset into 'mux_buf'.
* @channels: The channels associated with this muxer.
* @si: Keeps track of the PSI context.
* @num_streamed_pcr: Number of PCR packets streamed.
* @num_streamed_si: The number of PSI packets streamed.
* @mpeg_thread: Thread responsible for the muxer loop.
* @streaming: whether 'mpeg_thread' is running.
* @pcr_pid: The TS PID used for the PSI packets. All channels will share the
* same PCR.
* @transport_stream_id: The transport stream ID
* @priv: Private data.
*/
struct vidtv_mux {
struct dvb_frontend *fe;
struct device *dev;
struct vidtv_mux_timing timing;
u32 mux_rate_kbytes_sec;
DECLARE_HASHTABLE(pid_ctx, 3);
void (*on_new_packets_available_cb)(void *priv, u8 *buf, u32 npackets);
u8 *mux_buf;
u32 mux_buf_sz;
u32 mux_buf_offset;
struct vidtv_channel *channels;
struct vidtv_mux_si si;
u64 num_streamed_pcr;
u64 num_streamed_si;
struct work_struct mpeg_thread;
bool streaming;
u16 pcr_pid;
u16 transport_stream_id;
void *priv;
};
/**
* struct vidtv_mux_init_args - Arguments used to inix the muxer.
* @mux_rate_kbytes_sec: The bit rate for the TS, in kbytes.
* @on_new_packets_available_cb: A callback to inform of new TS packets ready.
* @mux_buf_sz: The size for 'mux_buf'.
* @pcr_period_usecs: How often we should send PCR packets.
* @si_period_usecs: How often we should send PSI packets.
* @pcr_pid: The TS PID used for the PSI packets. All channels will share the
* same PCR.
* @transport_stream_id: The transport stream ID
* @channels: an optional list of channels to use
* @priv: Private data.
*/
struct vidtv_mux_init_args {
u32 mux_rate_kbytes_sec;
void (*on_new_packets_available_cb)(void *priv, u8 *buf, u32 npackets);
u32 mux_buf_sz;
u64 pcr_period_usecs;
u64 si_period_usecs;
u16 pcr_pid;
u16 transport_stream_id;
struct vidtv_channel *channels;
void *priv;
};
struct vidtv_mux *vidtv_mux_init(struct dvb_frontend *fe,
struct device *dev,
struct vidtv_mux_init_args args);
void vidtv_mux_destroy(struct vidtv_mux *m);
void vidtv_mux_start_thread(struct vidtv_mux *m);
void vidtv_mux_stop_thread(struct vidtv_mux *m);
#endif //VIDTV_MUX_H
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