rtp: opus: add test for payloader dtx packet handling

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1571>

net/rtp/src/opus/mod.rs

@@ -2,3 +2,7 @@
 
 pub mod depay;
 pub mod pay;
+
+#[allow(clippy::module_inception)]
+#[cfg(test)]
+mod tests;

net/rtp/src/opus/tests/mod.rs

@@ -0,0 +1,3 @@
+// SPDX-License-Identifier: MPL-2.0
+
+mod tests;

net/rtp/src/opus/tests/tests.rs

@@ -0,0 +1,141 @@
+// GStreamer RTP Opus Payloader / Depayloader - unit tests
+//
+// Copyright (C) 2024 Tim-Philipp Müller <tim centricular com>
+//
+// This Source Code Form is subject to the terms of the Mozilla Public License, v2.0.
+// If a copy of the MPL was not distributed with this file, You can obtain one at
+// <https://mozilla.org/MPL/2.0/>.
+//
+// SPDX-License-Identifier: MPL-2.0
+
+use crate::tests::{run_test_pipeline, ExpectedBuffer, ExpectedPacket, Source};
+
+fn init() {
+    use std::sync::Once;
+    static INIT: Once = Once::new();
+
+    INIT.call_once(|| {
+        gst::init().unwrap();
+        crate::plugin_register_static().expect("rtpopus test");
+    });
+}
+
+// test_opus_pay_dtx
+//
+// Make sure payloader drops any DTX packets by the encoder (if so requested via the property)
+//
+#[test]
+fn test_opus_pay_dtx() {
+    // gst-launch-1.0 audiotestsrc wave=silence
+    //  ! opusenc dtx=true bitrate-type=vbr
+    //  ! fakesink silent=false dump=true
+    const OPUS_BUFFER_SILENCE: &[u8] = &[0xf8, 0xff, 0xfe];
+    const OPUS_BUFFER_SILENCE_DTX: &[u8] = &[0xf8];
+
+    fn make_buffer(
+        data: &'static [u8],
+        pts: gst::ClockTime,
+        duration: gst::ClockTime,
+        flags: gst::BufferFlags,
+    ) -> gst::Buffer {
+        let mut buf = gst::Buffer::from_slice(data);
+
+        let buf_ref = buf.get_mut().unwrap();
+        buf_ref.set_pts(pts);
+        buf_ref.set_duration(duration);
+        buf_ref.set_flags(flags);
+
+        buf
+    }
+
+    init();
+
+    for dtx_prop in [false, true] {
+        eprintln!("Testing rtpopuspay2 dtx={dtx_prop} ..");
+
+        let input_caps = gst::Caps::builder("audio/x-opus")
+            .field("rate", 48000i32)
+            .field("channels", 1i32)
+            .field("channel-mapping-family", 0i32)
+            .build();
+
+        let input_buffers = vec![
+            make_buffer(
+                OPUS_BUFFER_SILENCE,
+                gst::ClockTime::ZERO,
+                gst::ClockTime::from_useconds(13500),
+                gst::BufferFlags::DISCONT,
+            ),
+            make_buffer(
+                OPUS_BUFFER_SILENCE,
+                gst::ClockTime::from_useconds(13500),
+                gst::ClockTime::from_mseconds(20),
+                gst::BufferFlags::empty(),
+            ),
+            make_buffer(
+                OPUS_BUFFER_SILENCE_DTX,
+                gst::ClockTime::from_useconds(33500),
+                gst::ClockTime::from_mseconds(20),
+                gst::BufferFlags::empty(),
+            ),
+        ];
+
+        // TODO: check durations?
+        let mut expected_pay = vec![
+            vec![ExpectedPacket::builder()
+                .pts(gst::ClockTime::ZERO)
+                .flags(gst::BufferFlags::DISCONT | gst::BufferFlags::MARKER)
+                .pt(96)
+                .rtp_time(0)
+                .marker_bit(true)
+                .build()],
+            vec![ExpectedPacket::builder()
+                .pts(gst::ClockTime::from_useconds(13500))
+                .flags(gst::BufferFlags::empty())
+                .pt(96)
+                .rtp_time(648)
+                .marker_bit(false)
+                .build()],
+            vec![ExpectedPacket::builder()
+                .pts(gst::ClockTime::from_useconds(33500))
+                .flags(gst::BufferFlags::empty())
+                .pt(96)
+                .rtp_time(648 + 960)
+                .marker_bit(false)
+                .build()],
+        ];
+
+        // TODO: check durations?
+        let mut expected_depay = vec![
+            vec![ExpectedBuffer::builder()
+                .pts(gst::ClockTime::ZERO)
+                .size(3)
+                .flags(gst::BufferFlags::DISCONT | gst::BufferFlags::RESYNC)
+                .build()],
+            vec![ExpectedBuffer::builder()
+                .pts(gst::ClockTime::from_useconds(13500))
+                .size(3)
+                .flags(gst::BufferFlags::empty())
+                .build()],
+            vec![ExpectedBuffer::builder()
+                .pts(gst::ClockTime::from_useconds(33500))
+                .size(1)
+                .flags(gst::BufferFlags::empty())
+                .build()],
+        ];
+
+        if dtx_prop {
+            // Payloader should drop DTX buffer if dtx=true and not output it
+            expected_pay.pop();
+            expected_depay.pop();
+        }
+
+        run_test_pipeline(
+            Source::Buffers(input_caps, input_buffers),
+            &format!("rtpopuspay2 dtx={dtx_prop}"),
+            "rtpopusdepay2",
+            expected_pay,
+            expected_depay,
+        );
+    }
+}