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transcriberbin: new high-level bin for speech to Closed Caption

Browse source 
This new element puts together some of the elements we've written
in recent times (awstranscriber, tttocea608, textwrap, cccombiner)
into a convenience high-level element.

The design of the element is AV in -> AV (+ CC metas) out.

The element exposes property to set and unset a "passthrough" mode,
during which the transcriber element's state is set to NULL but kept
in the bin, in order for the user to be able to set properties on
sub elements no matter what the current mode is, using the
GstChildProxy interface.

In addition, the element ensures that the latency it reports stays
fixed so that playback continues uninterrupted.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/528>
This commit is contained in:
Mathieu Duponchelle 2021-06-22 22:08:08 +02:00
parent 3561c0ee98
commit 3cdc5870a1
4 changed files with 898 additions and 0 deletions
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1
video/closedcaption/Cargo.toml
View file

@ -8,6 +8,7 @@ description = "Rust Closed Caption Plugin"
repository = "https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs"
[dependencies]
anyhow = "1"
nom = "6.0"
either = "1"
uuid = { version = "0.8", features = ["v4"] }

2
video/closedcaption/src/lib.rs
View file

@ -36,6 +36,7 @@ mod mcc_parse;
mod parser_utils;
mod scc_enc;
mod scc_parse;
mod transcriberbin;
mod tttocea608;
mod tttojson;
mod ttutils;
@ -51,6 +52,7 @@ fn plugin_init(plugin: &gst::Plugin) -> Result<(), glib::BoolError> {
ccdetect::register(plugin)?;
tttojson::register(plugin)?;
cea608tojson::register(plugin)?;
transcriberbin::register(plugin)?;
Ok(())
}

858
video/closedcaption/src/transcriberbin/imp.rs Normal file
View file

@ -0,0 +1,858 @@
// Copyright (C) 2021 Mathieu Duponchelle <mathieu@centricular.com>
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Library General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public
// License along with this library; if not, write to the
// Free Software Foundation, Inc., 51 Franklin Street, Suite 500,
// Boston, MA 02110-1335, USA.
use crate::ttutils::Cea608Mode;
use anyhow::Error;
use gst::glib;
use gst::prelude::*;
use gst::subclass::prelude::*;
use gst::{gst_debug, gst_error, gst_info, gst_log, gst_trace};
use std::sync::Mutex;
use once_cell::sync::Lazy;
static CAT: Lazy<gst::DebugCategory> = Lazy::new(|| {
gst::DebugCategory::new(
"transcriberbin",
gst::DebugColorFlags::empty(),
Some("Transcribe and inject closed captions"),
)
});
const DEFAULT_PASSTHROUGH: bool = false;
const DEFAULT_LATENCY: gst::ClockTime = gst::ClockTime::from_seconds(4);
const DEFAULT_ACCUMULATE: gst::ClockTime = gst::ClockTime::ZERO;
const DEFAULT_MODE: Cea608Mode = Cea608Mode::RollUp2;
struct State {
framerate: Option<gst::Fraction>,
tearing_down: bool,
internal_bin: gst::Bin,
audio_queue_passthrough: gst::Element,
video_queue: gst::Element,
audio_tee: gst::Element,
transcriber_aconv: gst::Element,
transcriber: gst::Element,
transcriber_queue: gst::Element,
cccombiner: gst::Element,
transcription_bin: gst::Bin,
textwrap: gst::Element,
tttocea608: gst::Element,
cccapsfilter: gst::Element,
}
struct Settings {
cc_caps: gst::Caps,
latency: gst::ClockTime,
passthrough: bool,
accumulate_time: gst::ClockTime,
mode: Cea608Mode,
}
impl Default for Settings {
fn default() -> Self {
Self {
cc_caps: gst::Caps::builder("closedcaption/x-cea-608")
.field("format", &"raw")
.build(),
passthrough: DEFAULT_PASSTHROUGH,
latency: DEFAULT_LATENCY,
accumulate_time: DEFAULT_ACCUMULATE,
mode: DEFAULT_MODE,
}
}
}
// Struct containing all the element data
pub struct TranscriberBin {
audio_srcpad: gst::GhostPad,
video_srcpad: gst::GhostPad,
audio_sinkpad: gst::GhostPad,
video_sinkpad: gst::GhostPad,
state: Mutex<Option<State>>,
settings: Mutex<Settings>,
}
impl TranscriberBin {
fn construct_transcription_bin(
&self,
element: &super::TranscriberBin,
state: &mut State,
) -> Result<(), Error> {
gst_debug!(CAT, obj: element, "Building transcription bin");
let aqueue_transcription = gst::ElementFactory::make("queue", Some("transqueue"))?;
let ccconverter = gst::ElementFactory::make("ccconverter", None)?;
state.transcription_bin.add_many(&[
&aqueue_transcription,
&state.transcriber_aconv,
&state.transcriber,
&state.transcriber_queue,
&state.textwrap,
&state.tttocea608,
&ccconverter,
&state.cccapsfilter,
])?;
gst::Element::link_many(&[
&aqueue_transcription,
&state.transcriber_aconv,
&state.transcriber,
&state.transcriber_queue,
&state.textwrap,
&state.tttocea608,
&ccconverter,
&state.cccapsfilter,
])?;
let transcription_audio_sinkpad = gst::GhostPad::with_target(
Some("sink"),
&aqueue_transcription.static_pad("sink").unwrap(),
)?;
let transcription_audio_srcpad = gst::GhostPad::with_target(
Some("src"),
&state.cccapsfilter.static_pad("src").unwrap(),
)?;
state
.transcription_bin
.add_pad(&transcription_audio_sinkpad)?;
state
.transcription_bin
.add_pad(&transcription_audio_srcpad)?;
state
.transcriber_queue
.set_property("max-size-buffers", &0u32)
.unwrap();
state
.transcriber_queue
.set_property("max-size-time", &0u64)
.unwrap();
state.internal_bin.add(&state.transcription_bin)?;
state.textwrap.set_property("lines", &2u32).unwrap();
state.transcription_bin.set_locked_state(true);
Ok(())
}
fn construct_internal_bin(
&self,
element: &super::TranscriberBin,
state: &mut State,
) -> Result<(), Error> {
let aclocksync = gst::ElementFactory::make("clocksync", None)?;
let vclocksync = gst::ElementFactory::make("clocksync", None)?;
state.internal_bin.add_many(&[
&aclocksync,
&state.audio_tee,
&state.audio_queue_passthrough,
&vclocksync,
&state.video_queue,
&state.cccombiner,
])?;
aclocksync.link(&state.audio_tee)?;
state
.audio_tee
.link_pads(Some("src_%u"), &state.audio_queue_passthrough, Some("sink"))?;
vclocksync.link(&state.video_queue)?;
state
.video_queue
.link_pads(Some("src"), &state.cccombiner, Some("sink"))?;
let internal_audio_sinkpad = gst::GhostPad::with_target(
Some("audio_sink"),
&aclocksync.static_pad("sink").unwrap(),
)?;
let internal_audio_srcpad = gst::GhostPad::with_target(
Some("audio_src"),
&state.audio_queue_passthrough.static_pad("src").unwrap(),
)?;
let internal_video_sinkpad = gst::GhostPad::with_target(
Some("video_sink"),
&vclocksync.static_pad("sink").unwrap(),
)?;
let internal_video_srcpad = gst::GhostPad::with_target(
Some("video_src"),
&state.cccombiner.static_pad("src").unwrap(),
)?;
state.internal_bin.add_pad(&internal_audio_sinkpad)?;
state.internal_bin.add_pad(&internal_audio_srcpad)?;
state.internal_bin.add_pad(&internal_video_sinkpad)?;
state.internal_bin.add_pad(&internal_video_srcpad)?;
element.add(&state.internal_bin)?;
state
.cccombiner
.set_property("latency", &(100 * gst::ClockTime::MSECOND))
.unwrap();
self.audio_sinkpad
.set_target(Some(&state.internal_bin.static_pad("audio_sink").unwrap()))?;
self.audio_srcpad
.set_target(Some(&state.internal_bin.static_pad("audio_src").unwrap()))?;
self.video_sinkpad
.set_target(Some(&state.internal_bin.static_pad("video_sink").unwrap()))?;
self.video_srcpad
.set_target(Some(&state.internal_bin.static_pad("video_src").unwrap()))?;
self.construct_transcription_bin(element, state)?;
element.debug_to_dot_file(gst::DebugGraphDetails::all(), "Initial");
Ok(())
}
fn setup_transcription(&self, element: &super::TranscriberBin, state: &State) {
let settings = self.settings.lock().unwrap();
let mut cc_caps = settings.cc_caps.clone();
let cc_caps_mut = cc_caps.make_mut();
let s = cc_caps_mut.structure_mut(0).unwrap();
s.set("framerate", &state.framerate.unwrap());
state.cccapsfilter.set_property("caps", &cc_caps).unwrap();
let max_size_time = settings.latency + settings.accumulate_time;
for queue in &[&state.audio_queue_passthrough, &state.video_queue] {
queue.set_property("max-size-bytes", &0u32).unwrap();
queue.set_property("max-size-buffers", &0u32).unwrap();
queue.set_property("max-size-time", &max_size_time).unwrap();
}
let latency_ms = settings.latency.mseconds() as u32;
state
.transcriber
.set_property("latency", &latency_ms)
.unwrap();
if !settings.passthrough {
let audio_tee_pad = state.audio_tee.request_pad_simple("src_%u").unwrap();
let transcription_sink_pad = state.transcription_bin.static_pad("sink").unwrap();
audio_tee_pad.link(&transcription_sink_pad).unwrap();
state
.transcription_bin
.link_pads(Some("src"), &state.cccombiner, Some("caption"))
.unwrap();
state.transcription_bin.set_locked_state(false);
state.transcription_bin.sync_state_with_parent().unwrap();
}
drop(settings);
self.setup_cc_mode(element, state);
}
fn disable_transcription_bin(&self, element: &super::TranscriberBin) {
let mut state = self.state.lock().unwrap();
if let Some(ref mut state) = state.as_mut() {
state.tearing_down = false;
// At this point, we want to check whether passthrough
// has been unset in the meantime
let passthrough = self.settings.lock().unwrap().passthrough;
if passthrough {
let bin_sink_pad = state.transcription_bin.static_pad("sink").unwrap();
if let Some(audio_tee_pad) = bin_sink_pad.peer() {
audio_tee_pad.unlink(&bin_sink_pad).unwrap();
state.audio_tee.release_request_pad(&audio_tee_pad);
}
let bin_src_pad = state.transcription_bin.static_pad("src").unwrap();
if let Some(cccombiner_pad) = bin_src_pad.peer() {
bin_src_pad.unlink(&cccombiner_pad).unwrap();
state.cccombiner.release_request_pad(&cccombiner_pad);
}
state.transcription_bin.set_locked_state(true);
state.transcription_bin.set_state(gst::State::Null).unwrap();
element.debug_to_dot_file(gst::DebugGraphDetails::all(), "after-disable");
}
}
}
fn block_and_update(&self, element: &super::TranscriberBin, passthrough: bool) {
let mut s = self.state.lock().unwrap();
if let Some(ref mut state) = s.as_mut() {
if passthrough {
let sinkpad = state.transcription_bin.static_pad("sink").unwrap();
let element_weak = element.downgrade();
state.tearing_down = true;
drop(s);
let _ = sinkpad.add_probe(
gst::PadProbeType::IDLE
| gst::PadProbeType::BUFFER
| gst::PadProbeType::EVENT_DOWNSTREAM,
move |_pad, _info| {
let element = match element_weak.upgrade() {
None => return gst::PadProbeReturn::Pass,
Some(element) => element,
};
let this = TranscriberBin::from_instance(&element);
this.disable_transcription_bin(&element);
gst::PadProbeReturn::Remove
},
);
} else if state.tearing_down {
// Do nothing, wait for the previous transcription bin
// to finish tearing down
} else {
let audio_tee_pad = state.audio_tee.request_pad_simple("src_%u").unwrap();
let transcription_sink_pad = state.transcription_bin.static_pad("sink").unwrap();
audio_tee_pad.link(&transcription_sink_pad).unwrap();
state
.transcription_bin
.link_pads(Some("src"), &state.cccombiner, Some("caption"))
.unwrap();
state.transcription_bin.set_locked_state(false);
state.transcription_bin.sync_state_with_parent().unwrap();
element.debug_to_dot_file(gst::DebugGraphDetails::all(), "after-enable");
}
}
}
fn setup_cc_mode(&self, element: &super::TranscriberBin, state: &State) {
let mode = self.settings.lock().unwrap().mode;
gst_debug!(CAT, obj: element, "setting CC mode {:?}", mode);
state.tttocea608.set_property("mode", &mode).unwrap();
if mode.is_rollup() {
state
.textwrap
.set_property("accumulate-time", &0u64)
.unwrap();
} else {
let accumulate_time = self.settings.lock().unwrap().accumulate_time;
state
.textwrap
.set_property("accumulate-time", &accumulate_time)
.unwrap();
}
}
/* We make no ceremonies here because the function can only
* be called in READY */
fn relink_transcriber(
&self,
state: &mut State,
element: &super::TranscriberBin,
old_transcriber: &gst::Element,
) -> Result<(), Error> {
gst_error!(
CAT,
obj: element,
"Relinking transcriber, old: {:?}, new: {:?}",
old_transcriber,
state.transcriber
);
state.transcriber_aconv.unlink(old_transcriber);
old_transcriber.unlink(&state.transcriber_queue);
state.transcription_bin.remove(old_transcriber).unwrap();
old_transcriber.set_state(gst::State::Null).unwrap();
state.transcription_bin.add(&state.transcriber)?;
state.transcriber.sync_state_with_parent().unwrap();
gst::Element::link_many(&[
&state.transcriber_aconv,
&state.transcriber,
&state.transcriber_queue,
])?;
Ok(())
}
fn src_query(
&self,
pad: &gst::Pad,
element: &super::TranscriberBin,
query: &mut gst::QueryRef,
) -> bool {
use gst::QueryView;
gst_log!(CAT, obj: pad, "Handling query {:?}", query);
match query.view_mut() {
QueryView::Latency(ref mut q) => {
let mut upstream_query = gst::query::Latency::new();
let ret = pad.query_default(Some(element), &mut upstream_query);
if ret {
let (_, mut min, _) = upstream_query.result();
let settings = self.settings.lock().unwrap();
let received_framerate = {
let state = self.state.lock().unwrap();
if let Some(state) = state.as_ref() {
state.framerate.is_some()
} else {
false
}
};
if settings.passthrough || !received_framerate {
min += settings.latency + settings.accumulate_time;
} else if settings.mode.is_rollup() {
min += settings.accumulate_time;
}
q.set(true, min, gst::ClockTime::NONE);
eprintln!("Latency query response: {:?}", q);
}
ret
}
_ => pad.query_default(Some(element), query),
}
}
fn build_state(&self) -> Result<State, Error> {
let internal_bin = gst::Bin::new(Some("internal"));
let transcription_bin = gst::Bin::new(Some("transcription-bin"));
let audio_tee = gst::ElementFactory::make("tee", None)?;
let cccombiner = gst::ElementFactory::make("cccombiner", Some("cccombiner"))?;
let textwrap = gst::ElementFactory::make("textwrap", Some("textwrap"))?;
let tttocea608 = gst::ElementFactory::make("tttocea608", Some("tttocea608"))?;
let transcriber_aconv = gst::ElementFactory::make("audioconvert", None)?;
let transcriber = gst::ElementFactory::make("awstranscriber", Some("transcriber"))?;
let transcriber_queue = gst::ElementFactory::make("queue", None)?;
let audio_queue_passthrough = gst::ElementFactory::make("queue", None)?;
let video_queue = gst::ElementFactory::make("queue", None)?;
let cccapsfilter = gst::ElementFactory::make("capsfilter", None)?;
Ok(State {
framerate: None,
internal_bin,
audio_queue_passthrough,
video_queue,
transcriber_aconv,
transcriber,
transcriber_queue,
audio_tee,
cccombiner,
transcription_bin,
textwrap,
tttocea608,
cccapsfilter,
tearing_down: false,
})
}
fn video_sink_event(
&self,
pad: &gst::Pad,
element: &super::TranscriberBin,
event: gst::Event,
) -> bool {
use gst::EventView;
gst_log!(CAT, obj: pad, "Handling event {:?}", event);
match event.view() {
EventView::Caps(e) => {
let mut state = self.state.lock().unwrap();
if let Some(ref mut state) = state.as_mut() {
let caps = e.caps();
let s = caps.structure(0).unwrap();
let had_framerate = state.framerate.is_some();
if let Ok(framerate) = s.get::<gst::Fraction>("framerate") {
state.framerate = Some(framerate);
} else {
state.framerate = Some(gst::Fraction::new(30, 1));
}
if !had_framerate {
gst_info!(
CAT,
obj: element,
"Received video caps, setting up transcription"
);
self.setup_transcription(element, state);
}
}
pad.event_default(Some(element), event)
}
_ => pad.event_default(Some(element), event),
}
}
}
#[glib::object_subclass]
impl ObjectSubclass for TranscriberBin {
const NAME: &'static str = "RsTranscriberBin";
type Type = super::TranscriberBin;
type ParentType = gst::Bin;
fn with_class(klass: &Self::Class) -> Self {
let templ = klass.pad_template("sink_audio").unwrap();
let audio_sinkpad = gst::GhostPad::from_template(&templ, Some("sink_audio"));
let templ = klass.pad_template("src_audio").unwrap();
let audio_srcpad = gst::GhostPad::builder_with_template(&templ, Some("src_audio"))
.query_function(|pad, parent, query| {
TranscriberBin::catch_panic_pad_function(
parent,
|| false,
|transcriber, element| transcriber.src_query(pad.upcast_ref(), element, query),
)
})
.build();
let templ = klass.pad_template("sink_video").unwrap();
let video_sinkpad = gst::GhostPad::builder_with_template(&templ, Some("sink_video"))
.event_function(|pad, parent, event| {
TranscriberBin::catch_panic_pad_function(
parent,
|| false,
|transcriber, element| {
transcriber.video_sink_event(pad.upcast_ref(), element, event)
},
)
})
.build();
let templ = klass.pad_template("src_video").unwrap();
let video_srcpad = gst::GhostPad::builder_with_template(&templ, Some("src_video"))
.query_function(|pad, parent, query| {
TranscriberBin::catch_panic_pad_function(
parent,
|| false,
|transcriber, element| transcriber.src_query(pad.upcast_ref(), element, query),
)
})
.build();
Self {
audio_srcpad,
video_srcpad,
audio_sinkpad,
video_sinkpad,
state: Mutex::new(None),
settings: Mutex::new(Settings::default()),
}
}
}
impl ObjectImpl for TranscriberBin {
fn properties() -> &'static [glib::ParamSpec] {
static PROPERTIES: Lazy<Vec<glib::ParamSpec>> = Lazy::new(|| {
vec![
glib::ParamSpec::new_boolean(
"passthrough",
"Passthrough",
"Whether transcription should occur",
DEFAULT_PASSTHROUGH,
glib::ParamFlags::READWRITE | gst::PARAM_FLAG_MUTABLE_PLAYING,
),
glib::ParamSpec::new_uint(
"latency",
"Latency",
"Amount of milliseconds to allow the transcriber",
0u32,
std::u32::MAX,
DEFAULT_LATENCY.mseconds() as u32,
glib::ParamFlags::READWRITE | gst::PARAM_FLAG_MUTABLE_READY,
),
glib::ParamSpec::new_uint(
"accumulate-time",
"accumulate-time",
"Cut-off time for textwrap accumulation, in milliseconds (0=do not accumulate). \
Set this to a non-default value if you plan to switch to pop-on mode",
0,
u32::MAX,
DEFAULT_ACCUMULATE.mseconds() as u32,
glib::ParamFlags::READWRITE | gst::PARAM_FLAG_MUTABLE_READY,
),
glib::ParamSpec::new_enum(
"mode",
"Mode",
"Which closed caption mode to operate in",
Cea608Mode::static_type(),
DEFAULT_MODE as i32,
glib::ParamFlags::READWRITE | gst::PARAM_FLAG_MUTABLE_PLAYING,
),
glib::ParamSpec::new_boxed(
"cc-caps",
"Closed Caption caps",
"The expected format of the closed captions",
gst::Caps::static_type(),
glib::ParamFlags::READWRITE | gst::PARAM_FLAG_MUTABLE_READY,
),
glib::ParamSpec::new_object(
"transcriber",
"Transcriber",
"The transcriber element to use",
gst::Element::static_type(),
glib::ParamFlags::READWRITE | gst::PARAM_FLAG_MUTABLE_READY,
),
]
});
PROPERTIES.as_ref()
}
fn set_property(
&self,
obj: &Self::Type,
_id: usize,
value: &glib::Value,
pspec: &glib::ParamSpec,
) {
match pspec.name() {
"passthrough" => {
let mut settings = self.settings.lock().unwrap();
let old_passthrough = settings.passthrough;
let new_passthrough = value.get().expect("type checked upstream");
settings.passthrough = new_passthrough;
if old_passthrough != new_passthrough {
drop(settings);
self.block_and_update(obj, new_passthrough);
}
}
"latency" => {
let mut settings = self.settings.lock().unwrap();
settings.latency = gst::ClockTime::from_mseconds(
value.get::<u32>().expect("type checked upstream").into(),
);
}
"accumulate-time" => {
let mut settings = self.settings.lock().unwrap();
settings.accumulate_time = gst::ClockTime::from_mseconds(
value.get::<u32>().expect("type checked upstream").into(),
);
}
"mode" => {
let mut settings = self.settings.lock().unwrap();
let old_mode = settings.mode;
let new_mode = value.get().expect("type checked upstream");
settings.mode = new_mode;
if old_mode != new_mode {
drop(settings);
self.setup_cc_mode(obj, self.state.lock().unwrap().as_ref().unwrap());
}
}
"cc-caps" => {
let mut settings = self.settings.lock().unwrap();
settings.cc_caps = value.get().expect("type checked upstream");
}
"transcriber" => {
let mut s = self.state.lock().unwrap();
if let Some(ref mut state) = s.as_mut() {
let old_transcriber = state.transcriber.clone();
state.transcriber = value.get().expect("type checked upstream");
if old_transcriber != state.transcriber {
match self.relink_transcriber(state, obj, &old_transcriber) {
Ok(()) => (),
Err(err) => {
gst_error!(CAT, "invalid transcriber: {}", err);
drop(s);
*self.state.lock().unwrap() = None;
}
}
}
}
}
_ => unimplemented!(),
}
}
fn property(&self, _obj: &Self::Type, _id: usize, pspec: &glib::ParamSpec) -> glib::Value {
match pspec.name() {
"passthrough" => {
let settings = self.settings.lock().unwrap();
settings.passthrough.to_value()
}
"latency" => {
let settings = self.settings.lock().unwrap();
(settings.latency.mseconds() as u32).to_value()
}
"accumulate-time" => {
let settings = self.settings.lock().unwrap();
(settings.accumulate_time.mseconds() as u32).to_value()
}
"mode" => {
let settings = self.settings.lock().unwrap();
settings.mode.to_value()
}
"cc-caps" => {
let settings = self.settings.lock().unwrap();
settings.cc_caps.to_value()
}
"transcriber" => {
let state = self.state.lock().unwrap();
if let Some(ref state) = state.as_ref() {
state.transcriber.to_value()
} else {
let ret: Option<gst::Element> = None;
ret.to_value()
}
}
_ => unimplemented!(),
}
}
fn constructed(&self, obj: &Self::Type) {
self.parent_constructed(obj);
obj.add_pad(&self.audio_srcpad).unwrap();
obj.add_pad(&self.audio_sinkpad).unwrap();
obj.add_pad(&self.video_srcpad).unwrap();
obj.add_pad(&self.video_sinkpad).unwrap();
*self.state.lock().unwrap() = match self.build_state() {
Ok(mut state) => match self.construct_internal_bin(obj, &mut state) {
Ok(()) => Some(state),
Err(err) => {
gst_error!(CAT, "Failed to build internal bin: {}", err);
None
}
},
Err(err) => {
gst_error!(CAT, "Failed to build state: {}", err);
None
}
}
}
}
impl ElementImpl for TranscriberBin {
fn metadata() -> Option<&'static gst::subclass::ElementMetadata> {
static ELEMENT_METADATA: Lazy<gst::subclass::ElementMetadata> = Lazy::new(|| {
gst::subclass::ElementMetadata::new(
"TranscriberBin",
"Audio / Video / Text",
"Transcribes audio and adds it as closed captions",
"Mathieu Duponchelle <mathieu@centricular.com>",
)
});
Some(&*ELEMENT_METADATA)
}
fn pad_templates() -> &'static [gst::PadTemplate] {
static PAD_TEMPLATES: Lazy<Vec<gst::PadTemplate>> = Lazy::new(|| {
let caps = gst::Caps::new_simple("video/x-raw", &[]);
let video_src_pad_template = gst::PadTemplate::new(
"src_video",
gst::PadDirection::Src,
gst::PadPresence::Always,
&caps,
)
.unwrap();
let video_sink_pad_template = gst::PadTemplate::new(
"sink_video",
gst::PadDirection::Sink,
gst::PadPresence::Always,
&caps,
)
.unwrap();
let caps = gst::Caps::new_simple("audio/x-raw", &[]);
let audio_src_pad_template = gst::PadTemplate::new(
"src_audio",
gst::PadDirection::Src,
gst::PadPresence::Always,
&caps,
)
.unwrap();
let audio_sink_pad_template = gst::PadTemplate::new(
"sink_audio",
gst::PadDirection::Sink,
gst::PadPresence::Always,
&caps,
)
.unwrap();
vec![
video_src_pad_template,
video_sink_pad_template,
audio_src_pad_template,
audio_sink_pad_template,
]
});
PAD_TEMPLATES.as_ref()
}
fn change_state(
&self,
element: &Self::Type,
transition: gst::StateChange,
) -> Result<gst::StateChangeSuccess, gst::StateChangeError> {
gst_trace!(CAT, obj: element, "Changing state {:?}", transition);
match transition {
gst::StateChange::ReadyToPaused => {
let mut state = self.state.lock().unwrap();
if let Some(ref mut state) = state.as_mut() {
if state.framerate.is_some() {
gst_info!(
CAT,
obj: element,
"Received video caps, setting up transcription"
);
self.setup_transcription(element, state);
}
} else {
gst::element_error!(
element,
gst::StreamError::Failed,
["Can't change state with no state"]
);
return Err(gst::StateChangeError);
}
}
_ => (),
}
self.parent_change_state(element, transition)
}
}
impl BinImpl for TranscriberBin {}

37
video/closedcaption/src/transcriberbin/mod.rs Normal file
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// Copyright (C) 2021 Mathieu Duponchelle <mathieu@centricular.com>
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Library General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public
// License along with this library; if not, write to the
// Free Software Foundation, Inc., 51 Franklin Street, Suite 500,
// Boston, MA 02110-1335, USA.
use gst::glib;
use gst::prelude::*;
mod imp;
glib::wrapper! {
pub struct TranscriberBin(ObjectSubclass<imp::TranscriberBin>) @extends gst::Bin, gst::Element, gst::Object;
}
unsafe impl Send for TranscriberBin {}
unsafe impl Sync for TranscriberBin {}
pub fn register(plugin: &gst::Plugin) -> Result<(), glib::BoolError> {
gst::Element::register(
Some(plugin),
"transcriberbin",
gst::Rank::None,
TranscriberBin::static_type(),
)
}