1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
|
// Copyright (C) 2019 Sebastian Dröge <sebastian@centricular.com>
// Copyright (C) 2019 Jordan Petridis <jordan@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::structure;
use gst::subclass::prelude::*;
use gst::{gst_error, gst_log, gst_trace};
use gst_video::{self, ValidVideoTimeCode};
use once_cell::sync::Lazy;
use std::io::Write;
use std::sync::Mutex;
static CAT: Lazy<gst::DebugCategory> = Lazy::new(|| {
gst::DebugCategory::new(
"sccenc",
gst::DebugColorFlags::empty(),
Some("Scc Encoder Element"),
)
});
#[derive(Debug)]
struct State {
need_headers: bool,
expected_timecode: Option<ValidVideoTimeCode>,
internal_buffer: Vec<gst::Buffer>,
framerate: Option<gst::Fraction>,
}
impl Default for State {
fn default() -> Self {
Self {
need_headers: true,
expected_timecode: None,
internal_buffer: Vec::with_capacity(64),
framerate: None,
}
}
}
impl State {
// Write the header to the buffer and set need_headers to false
fn generate_headers(&mut self, buffer: &mut Vec<u8>) {
assert!(buffer.is_empty());
self.need_headers = false;
buffer.extend_from_slice(b"Scenarist_SCC V1.0\r\n\r\n");
}
fn encode_payload(outbuf: &mut Vec<u8>, slice: &[u8]) {
write!(outbuf, "{:02x}{:02x}", slice[0], slice[1]).unwrap();
}
fn generate_caption(
&mut self,
element: &super::SccEnc,
buffer: gst::Buffer,
) -> Result<Option<gst::Buffer>, gst::FlowError> {
// Arbitrary number that was chosen to keep in order
// to batch pushes of smaller buffers
const MAXIMUM_PACKETES_PER_LINE: usize = 16;
assert!(self.internal_buffer.len() < MAXIMUM_PACKETES_PER_LINE);
if buffer.size() != 2 {
gst::element_error!(
element,
gst::StreamError::Format,
["Wrongly sized CEA608 packet: {}", buffer.size()]
);
return Err(gst::FlowError::Error);
};
let mut timecode = buffer
.meta::<gst_video::VideoTimeCodeMeta>()
.ok_or_else(|| {
gst::element_error!(
element,
gst::StreamError::Format,
["Stream with timecodes on each buffer required"]
);
// If we neeed to skip a buffer, increment the frame if it exists
// to avoid getting out of sync
if let Some(ref mut timecode) = self.expected_timecode {
timecode.increment_frame();
}
gst::FlowError::Error
})?
.tc();
if self.expected_timecode.is_none() {
self.expected_timecode = Some(timecode.clone());
}
// if the timecode is different from the expected one,
// flush the previous line into the buffer, and push
// the new packet to the, now empty, internal buffer
if Some(&timecode) != self.expected_timecode.as_ref() {
let outbuf = self.write_line(element)?;
assert!(self.internal_buffer.is_empty());
self.internal_buffer.push(buffer);
timecode.increment_frame();
self.expected_timecode = Some(timecode);
return Ok(outbuf);
} else if let Some(ref mut timecode) = self.expected_timecode {
timecode.increment_frame();
}
self.internal_buffer.push(buffer);
if self.internal_buffer.len() == MAXIMUM_PACKETES_PER_LINE {
return self.write_line(element);
}
Ok(None)
}
// Flush the internal buffers into a line
fn write_line(
&mut self,
element: &super::SccEnc,
) -> Result<Option<gst::Buffer>, gst::FlowError> {
let mut outbuf = Vec::new();
let mut line_start = true;
if self.internal_buffer.is_empty() {
return Ok(None);
}
if self.need_headers {
self.generate_headers(&mut outbuf);
}
let first_buf = self.internal_buffer.first().unwrap();
for buffer in self.internal_buffer.iter() {
let map = buffer.map_readable().map_err(|_| {
gst::element_error!(
element,
gst::StreamError::Format,
["Failed to map buffer readable"]
);
gst::FlowError::Error
})?;
// If its the first packet in the line, write the timecode first
// else, separate the packets with a space
if line_start {
let timecode = buffer
.meta::<gst_video::VideoTimeCodeMeta>()
// Checked already before the buffer has been pushed to the
// internal_buffer
.expect("Buffer without timecode")
.tc();
let _ = write!(outbuf, "{}\t", timecode);
line_start = false;
} else {
outbuf.push(b' ');
}
Self::encode_payload(&mut outbuf, &*map);
}
outbuf.extend_from_slice(b"\r\n\r\n".as_ref());
let buffer = {
let mut buffer = gst::Buffer::from_mut_slice(outbuf);
let buf_mut = buffer.get_mut().unwrap();
// Something is seriously wrong else
assert!(self.framerate.is_some());
let framerate = self.framerate.unwrap();
let dur = gst::SECOND
.mul_div_floor(
self.internal_buffer.len() as u64 * *framerate.denom() as u64,
*framerate.numer() as u64,
)
.unwrap_or(gst::CLOCK_TIME_NONE);
buf_mut.set_duration(dur);
// Copy the metadata of the first buffer
first_buf
.copy_into(buf_mut, gst::BUFFER_COPY_METADATA, 0, None)
.expect("Failed to copy buffer metadata");
buf_mut.set_pts(first_buf.pts());
buffer
};
// Clear the internal buffer
self.internal_buffer.clear();
Ok(Some(buffer))
}
}
pub struct SccEnc {
srcpad: gst::Pad,
sinkpad: gst::Pad,
state: Mutex<State>,
}
impl SccEnc {
fn sink_chain(
&self,
pad: &gst::Pad,
element: &super::SccEnc,
buffer: gst::Buffer,
) -> Result<gst::FlowSuccess, gst::FlowError> {
gst_log!(CAT, obj: pad, "Handling buffer {:?}", buffer);
let mut state = self.state.lock().unwrap();
let res = state.generate_caption(element, buffer)?;
if let Some(outbuf) = res {
gst_trace!(CAT, obj: pad, "Pushing buffer {:?} to the pad", &outbuf);
drop(state);
self.srcpad.push(outbuf)?;
};
Ok(gst::FlowSuccess::Ok)
}
fn sink_event(&self, pad: &gst::Pad, element: &super::SccEnc, event: gst::Event) -> bool {
use gst::EventView;
gst_log!(CAT, obj: pad, "Handling event {:?}", event);
match event.view() {
EventView::Caps(ev) => {
let caps = ev.caps();
let s = caps.structure(0).unwrap();
let framerate = match s.get_some::<gst::Fraction>("framerate") {
Ok(framerate) => Some(framerate),
Err(structure::GetError::FieldNotFound { .. }) => {
gst_error!(CAT, obj: pad, "Caps without framerate");
return false;
}
err => panic!("SccEnc::sink_event caps: {:?}", err),
};
let mut state = self.state.lock().unwrap();
state.framerate = framerate;
// We send our own caps downstream
let caps = gst::Caps::builder("application/x-scc").build();
self.srcpad.push_event(gst::event::Caps::new(&caps))
}
EventView::Eos(_) => {
let mut state = self.state.lock().unwrap();
let outbuf = state.write_line(element);
if let Ok(Some(buffer)) = outbuf {
gst_trace!(CAT, obj: pad, "Pushing buffer {:?} to the pad", &buffer);
drop(state);
if self.srcpad.push(buffer).is_err() {
gst_error!(CAT, obj: pad, "Failed to push buffer to the pad");
return false;
}
} else if let Err(err) = outbuf {
gst_error!(CAT, obj: pad, "Failed to write a line after EOS: {:?}", err);
return false;
}
pad.event_default(Some(element), event)
}
_ => pad.event_default(Some(element), event),
}
}
fn src_event(&self, pad: &gst::Pad, element: &super::SccEnc, event: gst::Event) -> bool {
use gst::EventView;
gst_log!(CAT, obj: pad, "Handling event {:?}", event);
match event.view() {
EventView::Seek(_) => {
gst_log!(CAT, obj: pad, "Dropping seek event");
false
}
_ => pad.event_default(Some(element), event),
}
}
fn src_query(
&self,
pad: &gst::Pad,
element: &super::SccEnc,
query: &mut gst::QueryRef,
) -> bool {
use gst::QueryView;
gst_log!(CAT, obj: pad, "Handling query {:?}", query);
match query.view_mut() {
QueryView::Seeking(mut q) => {
// We don't support any seeking at all
let fmt = q.format();
q.set(
false,
gst::GenericFormattedValue::Other(fmt, -1),
gst::GenericFormattedValue::Other(fmt, -1),
);
true
}
_ => pad.query_default(Some(element), query),
}
}
}
#[glib::object_subclass]
impl ObjectSubclass for SccEnc {
const NAME: &'static str = "RsSccEnc";
type Type = super::SccEnc;
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| {
SccEnc::catch_panic_pad_function(
parent,
|| Err(gst::FlowError::Error),
|enc, element| enc.sink_chain(pad, element, buffer),
)
})
.event_function(|pad, parent, event| {
SccEnc::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"))
.event_function(|pad, parent, event| {
SccEnc::catch_panic_pad_function(
parent,
|| false,
|enc, element| enc.src_event(pad, element, event),
)
})
.query_function(|pad, parent, query| {
SccEnc::catch_panic_pad_function(
parent,
|| false,
|enc, element| enc.src_query(pad, element, query),
)
})
.build();
Self {
srcpad,
sinkpad,
state: Mutex::new(State::default()),
}
}
}
impl ObjectImpl for SccEnc {
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 SccEnc {
fn metadata() -> Option<&'static gst::subclass::ElementMetadata> {
static ELEMENT_METADATA: Lazy<gst::subclass::ElementMetadata> = Lazy::new(|| {
gst::subclass::ElementMetadata::new(
"Scc Encoder",
"Encoder/ClosedCaption",
"Encodes SCC Closed Caption Files",
"Sebastian Dröge <sebastian@centricular.com>, Jordan Petridis <jordan@centricular.com>",
)
});
Some(&*ELEMENT_METADATA)
}
fn pad_templates() -> &'static [gst::PadTemplate] {
static PAD_TEMPLATES: Lazy<Vec<gst::PadTemplate>> = Lazy::new(|| {
let framerates =
gst::List::new(&[&gst::Fraction::new(30000, 1001), &gst::Fraction::new(30, 1)]);
let caps = gst::Caps::builder("closedcaption/x-cea-608")
.field("format", &"raw")
.field("framerate", &framerates)
.build();
let sink_pad_template = gst::PadTemplate::new(
"sink",
gst::PadDirection::Sink,
gst::PadPresence::Always,
&caps,
)
.unwrap();
let caps = gst::Caps::builder("application/x-scc").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)
}
}
|