Parser can identify and sync the frame headers

audio/qoa/Cargo.toml

@@ -5,7 +5,7 @@ repository = "https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs"
 license = "MPL-2.0"
 edition = "2021"
 rust-version = "1.66"
-description = "GStreamer QOA (Quite OK Audio) Decoder Plugin"
+description = "GStreamer QOA (Quite OK Audio) Plugin"
 
 [dependencies]
 gst = { package = "gstreamer", git = "https://gitlab.freedesktop.org/gstreamer/gstreamer-rs" }

audio/qoa/src/lib.rs

@@ -9,10 +9,12 @@
 use gst::glib;
 
 mod qoadec;
+mod qoaparse;
 mod typefind;
 
 fn plugin_init(plugin: &gst::Plugin) -> Result<(), glib::BoolError> {
     qoadec::register(plugin)?;
+    qoaparse::register(plugin)?;
     typefind::register(plugin)
 }
 

audio/qoa/src/qoadec/imp.rs

@@ -71,7 +71,9 @@ impl ElementImpl for QoaDec {
 
     fn pad_templates() -> &'static [gst::PadTemplate] {
         static PAD_TEMPLATES: Lazy<Vec<gst::PadTemplate>> = Lazy::new(|| {
-            let sink_caps = gst::Caps::builder("audio/x-qoa").build();
+            let sink_caps = gst::Caps::builder("audio/x-qoa")
+                .field("parsed", true)
+                .build();
             let sink_pad_template = gst::PadTemplate::new(
                 "sink",
                 gst::PadDirection::Sink,

audio/qoa/src/qoaparse/imp.rs

@@ -0,0 +1,281 @@
+// Copyright (C) 2023 Rafael Caricio <rafael@caricio.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 glib::once_cell::sync::Lazy;
+use gst::glib;
+use gst::subclass::prelude::*;
+use gst_base::prelude::*;
+use gst_base::subclass::prelude::*;
+use qoaudio::{QOA_HEADER_SIZE, QOA_LMS_LEN, QOA_MAGIC, QOA_MIN_FILESIZE};
+use std::fmt;
+use std::sync::{Arc, Mutex};
+
+#[derive(Default, Debug, PartialEq)]
+struct State {
+    last_header: Option<FrameHeader>,
+}
+
+#[derive(Default)]
+pub struct QoaParse {
+    state: Arc<Mutex<State>>,
+}
+
+static CAT: Lazy<gst::DebugCategory> = Lazy::new(|| {
+    gst::DebugCategory::new(
+        "qoaparse",
+        gst::DebugColorFlags::empty(),
+        Some("Quite OK Audio parser"),
+    )
+});
+
+#[glib::object_subclass]
+impl ObjectSubclass for QoaParse {
+    const NAME: &'static str = "GstQoaParse";
+    type Type = super::QoaParse;
+    type ParentType = gst_base::BaseParse;
+}
+
+impl ObjectImpl for QoaParse {}
+
+impl GstObjectImpl for QoaParse {}
+
+impl ElementImpl for QoaParse {
+    fn metadata() -> Option<&'static gst::subclass::ElementMetadata> {
+        static ELEMENT_METADATA: Lazy<gst::subclass::ElementMetadata> = Lazy::new(|| {
+            gst::subclass::ElementMetadata::new(
+                "QOA parser",
+                "Codec/Parser/Audio",
+                "Quite OK Audio parser",
+                "Rafael Caricio <rafael@caricio.com>",
+            )
+        });
+
+        Some(&*ELEMENT_METADATA)
+    }
+
+    fn pad_templates() -> &'static [gst::PadTemplate] {
+        static PAD_TEMPLATES: Lazy<Vec<gst::PadTemplate>> = Lazy::new(|| {
+            let sink_caps = gst::Caps::builder("audio/x-qoa").build();
+            let sink_pad_template = gst::PadTemplate::new(
+                "sink",
+                gst::PadDirection::Sink,
+                gst::PadPresence::Always,
+                &sink_caps,
+            )
+            .unwrap();
+
+            let src_caps = gst::Caps::builder("audio/x-qoa")
+                .field("parsed", true)
+                .field("rate", gst::IntRange::<i32>::new(1, 16777215))
+                .field("channels", &gst::IntRange::<i32>::new(1, 255))
+                .build();
+            let src_pad_template = gst::PadTemplate::new(
+                "src",
+                gst::PadDirection::Src,
+                gst::PadPresence::Always,
+                &src_caps,
+            )
+            .unwrap();
+
+            vec![src_pad_template, sink_pad_template]
+        });
+
+        PAD_TEMPLATES.as_ref()
+    }
+}
+
+impl BaseParseImpl for QoaParse {
+    fn start(&self) -> Result<(), gst::ErrorMessage> {
+        gst::debug!(CAT, imp: self, "Starting...");
+
+        self.obj().set_min_frame_size(QOA_MIN_FILESIZE as u32);
+        Ok(())
+    }
+
+    fn handle_frame(
+        &self,
+        mut frame: gst_base::BaseParseFrame,
+    ) -> Result<(gst::FlowSuccess, u32), gst::FlowError> {
+        gst::trace!(CAT, imp: self, "Handling frame...");
+
+        let input = frame.buffer().unwrap();
+        let map = input.map_readable().map_err(|_| {
+            gst::element_imp_error!(
+                self,
+                gst::CoreError::Failed,
+                ["Failed to map input buffer readable"]
+            );
+            gst::FlowError::Error
+        })?;
+        let data = map.as_slice();
+
+        let file_header_size = {
+            if data.len() >= QOA_MIN_FILESIZE {
+                let magic = u32::from_be_bytes(data[0..4].try_into().unwrap());
+                if magic == QOA_MAGIC {
+                    QOA_HEADER_SIZE
+                } else {
+                    0
+                }
+            } else {
+                0
+            }
+        };
+
+        // We need at least a full frame header size to proceed
+        if data.len() < (file_header_size + QOA_HEADER_SIZE) {
+            // Error with not enough bytes to read the frame header
+            gst::element_imp_error!(
+                self,
+                gst::CoreError::Failed,
+                ["Not enough bytes to read the frame header"]
+            );
+            return Err(gst::FlowError::Error);
+        }
+
+        // We want to skip the file header (if content is coming
+        // from QOA file) so we ignore the first bytes. We want to
+        // read the frame header.
+        let raw_header = u64::from_be_bytes(
+            data[file_header_size..(file_header_size + QOA_HEADER_SIZE)]
+                .try_into()
+                .unwrap(),
+        );
+
+        // We don't know where in the byte stream we are reading from. We need to figure out where
+        // the frame header starts and sync to it. We try to parse and validate some traits of
+        // a valid QOA frame header.
+        let frame_header = match FrameHeader::parse(raw_header) {
+            Ok(header) => header,
+            Err(_) => {
+                // maybe the next byte will sync with a valid frame header
+                return Ok((gst::FlowSuccess::Ok, 1));
+            }
+        };
+
+        if data.len() < (file_header_size + frame_header.frame_size) {
+            gst::trace!(
+                CAT,
+                imp: self,
+                "Not enough bytes to read the frame, need {} bytes, have {}. Waiting for more data...",
+                file_header_size + frame_header.frame_size,
+                data.len()
+            );
+            return Ok((gst::FlowSuccess::Ok, 0));
+        }
+
+        drop(map);
+
+        let duration = (frame_header.num_samples_per_channel as u64)
+            .mul_div_floor(*gst::ClockTime::SECOND, frame_header.sample_rate as u64)
+            .map(gst::ClockTime::from_nseconds);
+
+        let buffer = frame.buffer_mut().unwrap();
+        buffer.set_duration(duration);
+        // all buffers are valid QOA frames which contain header
+        buffer.set_flags(gst::BufferFlags::HEADER);
+
+        gst::trace!(
+            CAT,
+            imp: self,
+            "Found frame {frame_header} with duration of {duration:?}",
+        );
+
+        let mut state = self.state.lock().unwrap();
+        if self.obj().src_pad().current_caps().is_none() || state.last_header != Some(frame_header)
+        {
+            // Set src pad caps
+            let src_caps = gst::Caps::builder("audio/x-qoa")
+                .field("parsed", true)
+                .field("rate", frame_header.sample_rate as i32)
+                .field("channels", frame_header.channels as i32)
+                .build();
+
+            gst::debug!(CAT, imp: self, "Setting src pad caps {:?}", src_caps);
+
+            self.obj()
+                .src_pad()
+                .push_event(gst::event::Caps::new(&src_caps));
+
+            state.last_header = Some(frame_header);
+        }
+
+        self.obj()
+            .finish_frame(frame, (file_header_size + frame_header.frame_size) as u32)?;
+
+        Ok((gst::FlowSuccess::Ok, 0))
+    }
+}
+
+pub const MAX_SLICES_PER_CHANNEL_PER_FRAME: usize = 256;
+
+pub struct InvalidFrameHeader;
+
+#[derive(Debug, Copy, Clone, Default)]
+pub struct FrameHeader {
+    /// Number of channels in this frame
+    pub channels: u8,
+    /// Sample rate in HZ for this frame
+    pub sample_rate: u32,
+    /// Samples per channel in this frame
+    pub num_samples_per_channel: u16,
+    /// Total size of the frame (includes header size itself)
+    pub frame_size: usize,
+}
+
+impl FrameHeader {
+    /// Parse and validate various traits of a valid frame header.
+    fn parse(frame_header: u64) -> Result<Self, InvalidFrameHeader> {
+        let channels = ((frame_header >> 56) & 0x0000ff) as u8;
+        let sample_rate = ((frame_header >> 32) & 0xffffff) as u32;
+        let num_samples_per_channel = ((frame_header >> 16) & 0x00ffff) as u16;
+        let frame_size = (frame_header & 0x00ffff) as usize;
+
+        if channels == 0 || sample_rate == 0 {
+            return Err(InvalidFrameHeader);
+        }
+
+        const LMS_SIZE: usize = 4;
+        let non_sample_data_size = QOA_HEADER_SIZE + QOA_LMS_LEN * LMS_SIZE * channels as usize;
+        if frame_size <= non_sample_data_size {
+            return Err(InvalidFrameHeader);
+        }
+        let data_size = frame_size - non_sample_data_size;
+        let num_slices = data_size / 8;
+
+        if num_slices % channels as usize != 0 {
+            return Err(InvalidFrameHeader);
+        }
+        if num_slices / channels as usize > MAX_SLICES_PER_CHANNEL_PER_FRAME {
+            return Err(InvalidFrameHeader);
+        }
+
+        Ok(FrameHeader {
+            channels,
+            sample_rate,
+            num_samples_per_channel,
+            frame_size,
+        })
+    }
+}
+
+impl PartialEq for FrameHeader {
+    fn eq(&self, other: &Self) -> bool {
+        self.channels == other.channels && self.sample_rate == other.sample_rate
+    }
+}
+
+impl fmt::Display for FrameHeader {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(
+            f,
+            "{{channels={}, sample_rate={}, num_samples_per_channel={}, frame_size={}}}",
+            self.channels, self.sample_rate, self.num_samples_per_channel, self.frame_size
+        )
+    }
+}

audio/qoa/src/qoaparse/mod.rs

@@ -0,0 +1,37 @@
+// Copyright (C) 2023 Rafael Caricio <rafael@caricio.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
+/**
+ * element-qoaparse:
+ * @short_description: Parser for audio encoded in QOA format.
+ *
+ * Parser for the Quite OK Audio format. Supports file and streaming modes.
+ *
+ * ## Example pipeline
+ * ```bash
+ * gst-launch-1.0 filesrc location=audio.qoa ! qoaparse ! qoadec ! autoaudiosink
+ * ```
+ *
+ * Since: plugins-rs-0.11.0-alpha.1
+ */
+use gst::glib;
+use gst::prelude::*;
+
+mod imp;
+
+glib::wrapper! {
+    pub struct QoaParse(ObjectSubclass<imp::QoaParse>) @extends gst_base::BaseParse, gst::Element, gst::Object;
+}
+
+pub fn register(plugin: &gst::Plugin) -> Result<(), glib::BoolError> {
+    gst::Element::register(
+        Some(plugin),
+        "qoaparse",
+        gst::Rank::Primary,
+        QoaParse::static_type(),
+    )
+}