mirror of
https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs.git
synced 2024-05-04 09:28:44 +00:00
285 lines
8 KiB
Rust
285 lines
8 KiB
Rust
// Copyright (C) 2020 Mathieu Duponchelle <mathieu@centricular.com>
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//
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// This Source Code Form is subject to the terms of the Mozilla Public License, v2.0.
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// If a copy of the MPL was not distributed with this file, You can obtain one at
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// <https://mozilla.org/MPL/2.0/>.
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//
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// SPDX-License-Identifier: MPL-2.0
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use gst::glib;
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use gst::prelude::*;
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use gst::subclass::prelude::*;
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use once_cell::sync::Lazy;
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use std::sync::Mutex;
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use serde::Serialize;
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#[derive(Serialize, Debug)]
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enum Line<'a> {
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Header {
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format: String,
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},
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Buffer {
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pts: Option<gst::ClockTime>,
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duration: Option<gst::ClockTime>,
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#[serde(borrow)]
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data: &'a serde_json::value::RawValue,
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},
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}
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static CAT: Lazy<gst::DebugCategory> = Lazy::new(|| {
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gst::DebugCategory::new(
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"jsongstenc",
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gst::DebugColorFlags::empty(),
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Some("GStreamer JSON Encoder Element"),
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)
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});
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#[derive(Debug, Default)]
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struct State {
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format: Option<String>,
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}
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pub struct JsonGstEnc {
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srcpad: gst::Pad,
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sinkpad: gst::Pad,
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state: Mutex<State>,
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}
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impl JsonGstEnc {
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fn sink_chain(
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&self,
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_pad: &gst::Pad,
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buffer: gst::Buffer,
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) -> Result<gst::FlowSuccess, gst::FlowError> {
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let pts = buffer.pts();
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let duration = buffer.duration();
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let mut state = self.state.lock().unwrap();
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if let Some(format) = &state.format {
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let line = Line::Header {
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format: format.to_string(),
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};
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let mut json = serde_json::to_string(&line).map_err(|err| {
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gst::element_imp_error!(
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self,
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gst::ResourceError::Write,
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["Failed to serialize as json {}", err]
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);
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gst::FlowError::Error
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})?;
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json.push('\n');
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let mut buf = gst::Buffer::from_mut_slice(json.into_bytes());
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{
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let buf_mut = buf.get_mut().unwrap();
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buf_mut.set_pts(pts);
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}
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state.format = None;
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drop(state);
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self.srcpad.push(buf)?;
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} else {
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drop(state);
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}
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let map = buffer.map_readable().map_err(|_| {
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gst::element_imp_error!(
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self,
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gst::ResourceError::Read,
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["Failed to map buffer readable"]
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);
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gst::FlowError::Error
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})?;
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let text = std::str::from_utf8(map.as_slice()).map_err(|err| {
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gst::element_imp_error!(
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self,
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gst::ResourceError::Read,
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["Failed to map decode as utf8: {}", err]
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);
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gst::FlowError::Error
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})?;
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let data: &serde_json::value::RawValue = serde_json::from_str(text).map_err(|err| {
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gst::element_imp_error!(
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self,
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gst::ResourceError::Read,
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["Failed to parse input as json: {}", err]
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);
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gst::FlowError::Error
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})?;
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let line = Line::Buffer {
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pts,
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duration,
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data,
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};
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let mut json = serde_json::to_string(&line).map_err(|err| {
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gst::element_imp_error!(
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self,
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gst::ResourceError::Write,
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["Failed to serialize as json {}", err]
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);
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gst::FlowError::Error
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})?;
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json.push('\n');
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let mut buf = gst::Buffer::from_mut_slice(json.into_bytes());
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{
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let buf_mut = buf.get_mut().unwrap();
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buf_mut.set_pts(pts);
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buf_mut.set_duration(duration);
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}
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self.srcpad.push(buf)
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}
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fn sink_event(&self, pad: &gst::Pad, event: gst::Event) -> bool {
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use gst::EventView;
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gst::log!(CAT, obj: pad, "Handling event {:?}", event);
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match event.view() {
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EventView::Caps(e) => {
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{
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let mut state = self.state.lock().unwrap();
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let caps = e.caps();
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let s = caps.structure(0).unwrap();
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state.format = match s.get::<Option<String>>("format") {
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Err(_) => None,
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Ok(format) => format,
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};
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}
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// We send our own caps downstream
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let caps = gst::Caps::builder("application/x-json").build();
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self.srcpad.push_event(gst::event::Caps::new(&caps))
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}
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EventView::Eos(_) => gst::Pad::event_default(pad, Some(&*self.instance()), event),
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_ => gst::Pad::event_default(pad, Some(&*self.instance()), event),
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}
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}
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}
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#[glib::object_subclass]
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impl ObjectSubclass for JsonGstEnc {
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const NAME: &'static str = "GstJsonGstEnc";
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type Type = super::JsonGstEnc;
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type ParentType = gst::Element;
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fn with_class(klass: &Self::Class) -> Self {
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let templ = klass.pad_template("sink").unwrap();
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let sinkpad = gst::Pad::builder_with_template(&templ, Some("sink"))
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.chain_function(|pad, parent, buffer| {
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JsonGstEnc::catch_panic_pad_function(
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parent,
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|| Err(gst::FlowError::Error),
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|enc| enc.sink_chain(pad, buffer),
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)
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})
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.event_function(|pad, parent, event| {
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JsonGstEnc::catch_panic_pad_function(
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parent,
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|| false,
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|enc| enc.sink_event(pad, event),
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)
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})
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.build();
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let templ = klass.pad_template("src").unwrap();
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let srcpad = gst::Pad::builder_with_template(&templ, Some("src")).build();
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Self {
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srcpad,
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sinkpad,
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state: Mutex::new(State::default()),
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}
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}
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}
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impl ObjectImpl for JsonGstEnc {
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fn constructed(&self) {
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self.parent_constructed();
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let obj = self.instance();
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obj.add_pad(&self.sinkpad).unwrap();
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obj.add_pad(&self.srcpad).unwrap();
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}
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}
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impl GstObjectImpl for JsonGstEnc {}
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impl ElementImpl for JsonGstEnc {
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fn metadata() -> Option<&'static gst::subclass::ElementMetadata> {
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static ELEMENT_METADATA: Lazy<gst::subclass::ElementMetadata> = Lazy::new(|| {
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gst::subclass::ElementMetadata::new(
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"GStreamer buffers to JSON",
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"Encoder/JSON",
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"Wraps buffers containing any valid top-level JSON structures \
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into higher level JSON objects, and outputs those as ndjson",
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"Mathieu Duponchelle <mathieu@centricular.com>",
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)
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});
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Some(&*ELEMENT_METADATA)
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}
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fn pad_templates() -> &'static [gst::PadTemplate] {
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static PAD_TEMPLATES: Lazy<Vec<gst::PadTemplate>> = Lazy::new(|| {
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let caps = gst::Caps::builder("application/x-json").build();
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let sink_pad_template = gst::PadTemplate::new(
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"sink",
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gst::PadDirection::Sink,
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gst::PadPresence::Always,
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&caps,
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)
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.unwrap();
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let caps = gst::Caps::builder("application/x-json").build();
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let src_pad_template = gst::PadTemplate::new(
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"src",
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gst::PadDirection::Src,
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gst::PadPresence::Always,
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&caps,
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)
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.unwrap();
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vec![src_pad_template, sink_pad_template]
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});
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PAD_TEMPLATES.as_ref()
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}
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fn change_state(
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&self,
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transition: gst::StateChange,
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) -> Result<gst::StateChangeSuccess, gst::StateChangeError> {
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gst::trace!(CAT, imp: self, "Changing state {:?}", transition);
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match transition {
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gst::StateChange::ReadyToPaused | gst::StateChange::PausedToReady => {
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// Reset the whole state
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let mut state = self.state.lock().unwrap();
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*state = State::default();
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}
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_ => (),
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}
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self.parent_change_state(transition)
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}
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}
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