183 lines
5.5 KiB
C
183 lines
5.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Vidtv serves as a reference DVB driver and helps validate the existing APIs
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* in the media subsystem. It can also aid developers working on userspace
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* applications.
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*
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* This file contains the muxer logic for TS packets from different
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* elementary streams.
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*
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* Loosely based on libavcodec/mpegtsenc.c
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*
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* Copyright (C) 2020 Daniel W. S. Almeida
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*/
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#ifndef VIDTV_MUX_H
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#define VIDTV_MUX_H
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#include <linux/hashtable.h>
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#include <linux/types.h>
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#include <linux/workqueue.h>
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#include <media/dvb_frontend.h>
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#include "vidtv_psi.h"
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/**
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* struct vidtv_mux_timing - Timing related information
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*
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* This is used to decide when PCR or PSI packets should be sent. This will also
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* provide storage for the clock, which is used to compute the value for the PCR.
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*
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* @start_jiffies: The value of 'jiffies' when we started the mux thread.
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* @current_jiffies: The value of 'jiffies' for the current iteration.
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* @past_jiffies: The value of 'jiffies' for the past iteration.
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* @clk: A 27Mhz clock from which we will drive the PCR. Updated proportionally
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* on every iteration.
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* @pcr_period_usecs: How often we should send PCR packets.
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* @si_period_usecs: How often we should send PSI packets.
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*/
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struct vidtv_mux_timing {
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u64 start_jiffies;
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u64 current_jiffies;
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u64 past_jiffies;
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u64 clk;
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u64 pcr_period_usecs;
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u64 si_period_usecs;
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};
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/**
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* struct vidtv_mux_si - Store the PSI context.
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*
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* This is used to store the PAT, PMT sections and SDT in use by the muxer.
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*
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* The muxer acquire these by looking into the hardcoded channels in
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* vidtv_channel and then periodically sends the TS packets for them>
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*
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* @pat: The PAT in use by the muxer.
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* @pmt_secs: The PMT sections in use by the muxer. One for each program in the PAT.
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* @sdt: The SDT in use by the muxer.
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* @nit: The NIT in use by the muxer.
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* @eit: the EIT in use by the muxer.
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*/
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struct vidtv_mux_si {
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/* the SI tables */
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struct vidtv_psi_table_pat *pat;
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struct vidtv_psi_table_pmt **pmt_secs; /* the PMT sections */
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struct vidtv_psi_table_sdt *sdt;
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struct vidtv_psi_table_nit *nit;
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struct vidtv_psi_table_eit *eit;
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};
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/**
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* struct vidtv_mux_pid_ctx - Store the context for a given TS PID.
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* @pid: The TS PID.
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* @cc: The continuity counter for this PID. It is incremented on every TS
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* pack and it will wrap around at 0xf0. If the decoder notices a sudden jump in
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* this counter this will trigger a discontinuity state.
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* @h: This is embedded in a hash table, mapping pid -> vidtv_mux_pid_ctx
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*/
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struct vidtv_mux_pid_ctx {
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u16 pid;
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u8 cc; /* continuity counter */
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struct hlist_node h;
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};
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/**
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* struct vidtv_mux - A muxer abstraction loosely based in libavcodec/mpegtsenc.c
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* @fe: The frontend structure allocated by the muxer.
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* @dev: pointer to struct device.
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* @timing: Keeps track of timing related information.
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* @mux_rate_kbytes_sec: The bit rate for the TS, in kbytes.
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* @pid_ctx: A hash table to keep track of per-PID metadata.
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* @on_new_packets_available_cb: A callback to inform of new TS packets ready.
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* @mux_buf: A pointer to a buffer for this muxer. TS packets are stored there
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* and then passed on to the bridge driver.
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* @mux_buf_sz: The size for 'mux_buf'.
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* @mux_buf_offset: The current offset into 'mux_buf'.
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* @channels: The channels associated with this muxer.
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* @si: Keeps track of the PSI context.
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* @num_streamed_pcr: Number of PCR packets streamed.
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* @num_streamed_si: The number of PSI packets streamed.
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* @mpeg_thread: Thread responsible for the muxer loop.
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* @streaming: whether 'mpeg_thread' is running.
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* @pcr_pid: The TS PID used for the PSI packets. All channels will share the
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* same PCR.
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* @transport_stream_id: The transport stream ID
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* @network_id: The network ID
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* @network_name: The network name
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* @priv: Private data.
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*/
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struct vidtv_mux {
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struct dvb_frontend *fe;
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struct device *dev;
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struct vidtv_mux_timing timing;
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u32 mux_rate_kbytes_sec;
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DECLARE_HASHTABLE(pid_ctx, 3);
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void (*on_new_packets_available_cb)(void *priv, u8 *buf, u32 npackets);
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u8 *mux_buf;
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u32 mux_buf_sz;
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u32 mux_buf_offset;
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struct vidtv_channel *channels;
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struct vidtv_mux_si si;
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u64 num_streamed_pcr;
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u64 num_streamed_si;
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struct work_struct mpeg_thread;
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bool streaming;
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u16 pcr_pid;
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u16 transport_stream_id;
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u16 network_id;
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char *network_name;
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void *priv;
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};
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/**
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* struct vidtv_mux_init_args - Arguments used to inix the muxer.
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* @mux_rate_kbytes_sec: The bit rate for the TS, in kbytes.
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* @on_new_packets_available_cb: A callback to inform of new TS packets ready.
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* @mux_buf_sz: The size for 'mux_buf'.
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* @pcr_period_usecs: How often we should send PCR packets.
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* @si_period_usecs: How often we should send PSI packets.
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* @pcr_pid: The TS PID used for the PSI packets. All channels will share the
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* same PCR.
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* @transport_stream_id: The transport stream ID
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* @channels: an optional list of channels to use
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* @network_id: The network ID
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* @network_name: The network name
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* @priv: Private data.
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*/
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struct vidtv_mux_init_args {
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u32 mux_rate_kbytes_sec;
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void (*on_new_packets_available_cb)(void *priv, u8 *buf, u32 npackets);
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u32 mux_buf_sz;
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u64 pcr_period_usecs;
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u64 si_period_usecs;
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u16 pcr_pid;
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u16 transport_stream_id;
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struct vidtv_channel *channels;
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u16 network_id;
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char *network_name;
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void *priv;
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};
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struct vidtv_mux *vidtv_mux_init(struct dvb_frontend *fe,
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struct device *dev,
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struct vidtv_mux_init_args *args);
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void vidtv_mux_destroy(struct vidtv_mux *m);
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void vidtv_mux_start_thread(struct vidtv_mux *m);
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void vidtv_mux_stop_thread(struct vidtv_mux *m);
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#endif //VIDTV_MUX_H
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