aws/polly: expose property for overflow control

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1965>

docs/plugins/gst_plugins_cache.json

@@ -87,6 +87,18 @@
                         "type": "GstValueArray",
                         "writable": true
                     },
+                    "overflow": {
+                        "blurb": "Defines how output audio with a longer duration than input text should be handled",
+                        "conditionally-available": false,
+                        "construct": false,
+                        "construct-only": false,
+                        "controllable": false,
+                        "default": "clip (0)",
+                        "mutable": "ready",
+                        "readable": true,
+                        "type": "GstAwsOverflow",
+                        "writable": true
+                    },
                     "secret-access-key": {
                         "blurb": "AWS Secret Access Key",
                         "conditionally-available": false,
@@ -1372,6 +1384,26 @@
         "filename": "gstaws",
         "license": "MPL",
         "other-types": {
+            "GstAwsOverflow": {
+                "kind": "enum",
+                "values": [
+                    {
+                        "desc": "Clip",
+                        "name": "clip",
+                        "value": "0"
+                    },
+                    {
+                        "desc": "Overlap",
+                        "name": "overlap",
+                        "value": "1"
+                    },
+                    {
+                        "desc": "Shift",
+                        "name": "shift",
+                        "value": "2"
+                    }
+                ]
+            },
             "GstAwsPollyEngine": {
                 "kind": "enum",
                 "values": [

net/aws/src/polly/imp.rs

@@ -21,7 +21,7 @@ use std::sync::Mutex;
 
 use std::sync::LazyLock;
 
-use super::{AwsPollyEngine, AwsPollyLanguageCode, AwsPollyVoiceId, CAT};
+use super::{AwsOverflow, AwsPollyEngine, AwsPollyLanguageCode, AwsPollyVoiceId, CAT};
 use crate::s3utils::RUNTIME;
 use anyhow::{anyhow, Error};
 
@@ -35,6 +35,7 @@ const DEFAULT_ENGINE: AwsPollyEngine = AwsPollyEngine::Neural;
 const DEFAULT_LANGUAGE_CODE: AwsPollyLanguageCode = AwsPollyLanguageCode::None;
 const DEFAULT_VOICE_ID: AwsPollyVoiceId = AwsPollyVoiceId::Aria;
 const DEFAULT_SSML_SET_MAX_DURATION: bool = false;
+const DEFAULT_OVERFLOW: AwsOverflow = AwsOverflow::Clip;
 
 #[derive(Debug, Clone)]
 pub(super) struct Settings {
@@ -47,6 +48,7 @@ pub(super) struct Settings {
     voice_id: AwsPollyVoiceId,
     lexicon_names: gst::Array,
     ssml_set_max_duration: bool,
+    overflow: AwsOverflow,
 }
 
 impl Default for Settings {
@@ -61,6 +63,7 @@ impl Default for Settings {
             voice_id: DEFAULT_VOICE_ID,
             lexicon_names: gst::Array::default(),
             ssml_set_max_duration: DEFAULT_SSML_SET_MAX_DURATION,
+            overflow: DEFAULT_OVERFLOW,
         }
     }
 }
@@ -158,7 +161,7 @@ impl Polly {
     }
 
     async fn send(&self, inbuf: gst::Buffer) -> Result<gst::Buffer, Error> {
-        let pts = inbuf
+        let mut pts = inbuf
             .pts()
             .ok_or_else(|| anyhow!("Stream with timestamped buffers required"))?;
 
@@ -227,15 +230,47 @@ impl Polly {
         })?;
         let blob = resp.audio_stream.collect().await?;
 
-        let mut buf = gst::Buffer::from_slice(blob.into_bytes());
-        let mut state = self.state.lock().unwrap();
+        let mut bytes = blob.into_bytes();
+
+        let overflow = self.settings.lock().unwrap().overflow;
+
+        if matches!(overflow, AwsOverflow::Clip) {
+            let max_expected_bytes = duration
+                .nseconds()
+                .mul_div_floor(32_000, 1_000_000_000)
+                .unwrap()
+                / 2
+                * 2;
+
+            gst::debug!(
+                CAT,
+                "Received {} bytes, max expected {}",
+                bytes.len(),
+                max_expected_bytes
+            );
+
+            bytes.truncate(max_expected_bytes as usize);
+        }
 
         let duration = gst::ClockTime::from_nseconds(
-            (buf.size() as u64)
+            (bytes.len() as u64)
                 .mul_div_round(1_000_000_000, 32_000)
                 .unwrap(),
         );
 
+        let mut buf = gst::Buffer::from_slice(bytes);
+        let mut state = self.state.lock().unwrap();
+
+        if let Some(position) = state.out_segment.position() {
+            if matches!(overflow, AwsOverflow::Shift) && pts < position {
+                gst::debug!(
+                    CAT,
+                    "received pts {pts} < position {position}, shifting forward"
+                );
+                pts = position;
+            }
+        }
+
         let discont = state
             .out_segment
             .position()
@@ -248,7 +283,7 @@ impl Polly {
             buf_mut.set_duration(duration);
 
             if discont {
-                gst::log!(CAT, imp = self, "Marking buffer discont");
+                gst::debug!(CAT, imp = self, "Marking buffer discont");
                 buf_mut.set_flags(gst::BufferFlags::DISCONT);
             }
             inbuf.foreach_meta(|meta| {
@@ -521,6 +556,11 @@ impl ObjectImpl for Polly {
                     .default_value(DEFAULT_SSML_SET_MAX_DURATION)
                     .mutable_ready()
                     .build(),
+                glib::ParamSpecEnum::builder_with_default("overflow", DEFAULT_OVERFLOW)
+                    .nick("Overflow")
+                    .blurb("Defines how output audio with a longer duration than input text should be handled")
+                    .mutable_ready()
+                    .build(),
             ]
         });
 
@@ -581,6 +621,10 @@ impl ObjectImpl for Polly {
                 let mut settings = self.settings.lock().unwrap();
                 settings.ssml_set_max_duration = value.get().expect("type checked upstream");
             }
+            "overflow" => {
+                let mut settings = self.settings.lock().unwrap();
+                settings.overflow = value.get::<AwsOverflow>().expect("type checked upstream");
+            }
             _ => unimplemented!(),
         }
     }
@@ -623,6 +667,10 @@ impl ObjectImpl for Polly {
                 let settings = self.settings.lock().unwrap();
                 settings.ssml_set_max_duration.to_value()
             }
+            "overflow" => {
+                let settings = self.settings.lock().unwrap();
+                settings.overflow.to_value()
+            }
             _ => unimplemented!(),
         }
     }

net/aws/src/polly/mod.rs

@@ -398,6 +398,19 @@ impl From<AwsPollyLanguageCode> for LanguageCode {
     }
 }
 
+#[derive(Debug, Eq, PartialEq, Ord, PartialOrd, Hash, Clone, Copy, glib::Enum)]
+#[repr(u32)]
+#[enum_type(name = "GstAwsOverflow")]
+#[non_exhaustive]
+pub enum AwsOverflow {
+    #[enum_value(name = "Clip", nick = "clip")]
+    Clip = 0,
+    #[enum_value(name = "Overlap", nick = "overlap")]
+    Overlap = 1,
+    #[enum_value(name = "Shift", nick = "shift")]
+    Shift = 2,
+}
+
 glib::wrapper! {
     pub struct Polly(ObjectSubclass<imp::Polly>) @extends gst::Element, gst::Object;
 }
@@ -408,6 +421,7 @@ pub fn register(plugin: &gst::Plugin) -> Result<(), glib::BoolError> {
         AwsPollyEngine::static_type().mark_as_plugin_api(gst::PluginAPIFlags::empty());
         AwsPollyVoiceId::static_type().mark_as_plugin_api(gst::PluginAPIFlags::empty());
         AwsPollyLanguageCode::static_type().mark_as_plugin_api(gst::PluginAPIFlags::empty());
+        AwsOverflow::static_type().mark_as_plugin_api(gst::PluginAPIFlags::empty());
     }
     gst::Element::register(
         Some(plugin),