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// Copyright (C) 2020 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 glib::subclass::prelude::*;
use gst::prelude::*;
use gst::subclass::prelude::*;
use gst::{gst_log, gst_trace};
use once_cell::sync::Lazy;
use std::sync::Mutex;
use serde::Serialize;
#[derive(Serialize, Debug)]
enum Line<'a> {
Header {
format: String,
},
Buffer {
pts: i64,
duration: i64,
#[serde(borrow)]
data: &'a serde_json::value::RawValue,
},
}
static CAT: Lazy<gst::DebugCategory> = Lazy::new(|| {
gst::DebugCategory::new(
"jsongstenc",
gst::DebugColorFlags::empty(),
Some("GStreamer JSON Encoder Element"),
)
});
#[derive(Debug)]
struct State {
start_ts: gst::ClockTime,
end_ts: gst::ClockTime,
current_line: String,
format: Option<String>,
}
impl Default for State {
fn default() -> Self {
Self {
start_ts: gst::CLOCK_TIME_NONE,
end_ts: gst::CLOCK_TIME_NONE,
current_line: "".to_string(),
format: None,
}
}
}
pub struct JsonGstEnc {
srcpad: gst::Pad,
sinkpad: gst::Pad,
state: Mutex<State>,
}
impl JsonGstEnc {
fn sink_chain(
&self,
_pad: &gst::Pad,
element: &super::JsonGstEnc,
buffer: gst::Buffer,
) -> Result<gst::FlowSuccess, gst::FlowError> {
let pts = buffer.pts();
let duration = buffer.duration();
let mut state = self.state.lock().unwrap();
if let Some(format) = &state.format {
let line = Line::Header {
format: format.to_string(),
};
let mut json = serde_json::to_string(&line).map_err(|err| {
gst::element_error!(
element,
gst::ResourceError::Write,
["Failed to serialize as json {}", err]
);
gst::FlowError::Error
})?;
json.push('\n');
let mut buf = gst::Buffer::from_mut_slice(json.into_bytes());
{
let buf_mut = buf.get_mut().unwrap();
buf_mut.set_pts(pts);
}
state.format = None;
drop(state);
self.srcpad.push(buf)?;
} else {
drop(state);
}
let map = buffer.map_readable().map_err(|_| {
gst::element_error!(
element,
gst::ResourceError::Read,
["Failed to map buffer readable"]
);
gst::FlowError::Error
})?;
let text = std::str::from_utf8(map.as_slice()).map_err(|err| {
gst::element_error!(
element,
gst::ResourceError::Read,
["Failed to map decode as utf8: {}", err]
);
gst::FlowError::Error
})?;
let data: &serde_json::value::RawValue = serde_json::from_str(text).map_err(|err| {
gst::element_error!(
element,
gst::ResourceError::Read,
["Failed to parse input as json: {}", err]
);
gst::FlowError::Error
})?;
let line = Line::Buffer {
pts: pts.unwrap_or(std::u64::MAX) as i64,
duration: duration.unwrap_or(std::u64::MAX) as i64,
data,
};
let mut json = serde_json::to_string(&line).map_err(|err| {
gst::element_error!(
element,
gst::ResourceError::Write,
["Failed to serialize as json {}", err]
);
gst::FlowError::Error
})?;
json.push('\n');
let mut buf = gst::Buffer::from_mut_slice(json.into_bytes());
{
let buf_mut = buf.get_mut().unwrap();
buf_mut.set_pts(pts);
buf_mut.set_duration(duration);
}
self.srcpad.push(buf)
}
fn sink_event(&self, pad: &gst::Pad, element: &super::JsonGstEnc, 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();
let caps = e.caps();
let s = caps.structure(0).unwrap();
state.format = match s.get::<Option<String>>("format") {
Err(_) => None,
Ok(format) => format,
};
}
// We send our own caps downstream
let caps = gst::Caps::builder("application/x-json").build();
self.srcpad.push_event(gst::event::Caps::new(&caps))
}
EventView::Eos(_) => pad.event_default(Some(element), event),
_ => pad.event_default(Some(element), event),
}
}
}
#[glib::object_subclass]
impl ObjectSubclass for JsonGstEnc {
const NAME: &'static str = "RsJsonGstEnc";
type Type = super::JsonGstEnc;
type ParentType = gst::Element;
fn with_class(klass: &Self::Class) -> Self {
let templ = klass.pad_template("sink").unwrap();
let sinkpad = gst::Pad::builder_with_template(&templ, Some("sink"))
.chain_function(|pad, parent, buffer| {
JsonGstEnc::catch_panic_pad_function(
parent,
|| Err(gst::FlowError::Error),
|enc, element| enc.sink_chain(pad, element, buffer),
)
})
.event_function(|pad, parent, event| {
JsonGstEnc::catch_panic_pad_function(
parent,
|| false,
|enc, element| enc.sink_event(pad, element, event),
)
})
.build();
let templ = klass.pad_template("src").unwrap();
let srcpad = gst::Pad::builder_with_template(&templ, Some("src")).build();
Self {
srcpad,
sinkpad,
state: Mutex::new(State::default()),
}
}
}
impl ObjectImpl for JsonGstEnc {
fn constructed(&self, obj: &Self::Type) {
self.parent_constructed(obj);
obj.add_pad(&self.sinkpad).unwrap();
obj.add_pad(&self.srcpad).unwrap();
}
}
impl ElementImpl for JsonGstEnc {
fn metadata() -> Option<&'static gst::subclass::ElementMetadata> {
static ELEMENT_METADATA: Lazy<gst::subclass::ElementMetadata> = Lazy::new(|| {
gst::subclass::ElementMetadata::new(
"GStreamer buffers to JSON",
"Encoder/JSON",
"Wraps buffers containing any valid top-level JSON structures \
into higher level JSON objects, and outputs those as ndjson",
"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::builder("application/x-json").build();
let sink_pad_template = gst::PadTemplate::new(
"sink",
gst::PadDirection::Sink,
gst::PadPresence::Always,
&caps,
)
.unwrap();
let caps = gst::Caps::builder("application/x-json").build();
let src_pad_template = gst::PadTemplate::new(
"src",
gst::PadDirection::Src,
gst::PadPresence::Always,
&caps,
)
.unwrap();
vec![src_pad_template, 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 | gst::StateChange::PausedToReady => {
// Reset the whole state
let mut state = self.state.lock().unwrap();
*state = State::default();
}
_ => (),
}
self.parent_change_state(element, transition)
}
}
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