feat(alsa): add native dsd support (#1078)

Author: ljufa

CHANGELOG.md

@@ -73,6 +73,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **WASAPI**: `Send` and `Sync` implementations to `Stream`.
 - **WebAudio**: `Send` and `Sync` implementations to `Stream`.
 - **WebAudio**: `BufferSize::Fixed` validation against supported range.
+- **ALSA**: Add support for native DSD playback.
 
 ### Changed
 

examples/record_wav.rs

@@ -150,7 +150,9 @@ fn main() -> Result<(), anyhow::Error> {
 }
 
 fn sample_format(format: cpal::SampleFormat) -> hound::SampleFormat {
-    if format.is_float() {
+    if format.is_dsd() {
+        panic!("DSD formats cannot be written to WAV files");
+    } else if format.is_float() {
         hound::SampleFormat::Float
     } else {
         hound::SampleFormat::Int

src/host/alsa/mod.rs

@@ -475,7 +475,7 @@ impl Device {
         // Test both LE and BE formats to detect what the hardware actually supports.
         // LE is listed first as it's the common case for most audio hardware.
         // Hardware reports its supported formats regardless of CPU endianness.
-        const FORMATS: [(SampleFormat, alsa::pcm::Format); 18] = [
+        const FORMATS: [(SampleFormat, alsa::pcm::Format); 23] = [
             (SampleFormat::I8, alsa::pcm::Format::S8),
             (SampleFormat::U8, alsa::pcm::Format::U8),
             (SampleFormat::I16, alsa::pcm::Format::S16LE),
@@ -494,6 +494,11 @@ impl Device {
             (SampleFormat::F32, alsa::pcm::Format::FloatBE),
             (SampleFormat::F64, alsa::pcm::Format::Float64LE),
             (SampleFormat::F64, alsa::pcm::Format::Float64BE),
+            (SampleFormat::DsdU8, alsa::pcm::Format::DSDU8),
+            (SampleFormat::DsdU16, alsa::pcm::Format::DSDU16LE),
+            (SampleFormat::DsdU16, alsa::pcm::Format::DSDU16BE),
+            (SampleFormat::DsdU32, alsa::pcm::Format::DSDU32LE),
+            (SampleFormat::DsdU32, alsa::pcm::Format::DSDU32BE),
             //SND_PCM_FORMAT_IEC958_SUBFRAME_LE,
             //SND_PCM_FORMAT_IEC958_SUBFRAME_BE,
             //SND_PCM_FORMAT_MU_LAW,
@@ -1262,6 +1267,7 @@ fn fill_with_equilibrium(buffer: &mut [u8], sample_format: SampleFormat) {
             }
         }};
     }
+    const DSD_SILENCE_BYTE: u8 = 0x69;
 
     match sample_format {
         SampleFormat::I8 => fill_typed!(i8),
@@ -1278,6 +1284,9 @@ fn fill_with_equilibrium(buffer: &mut [u8], sample_format: SampleFormat) {
         SampleFormat::U64 => fill_typed!(u64),
         SampleFormat::F32 => fill_typed!(f32),
         SampleFormat::F64 => fill_typed!(f64),
+        SampleFormat::DsdU8 | SampleFormat::DsdU16 | SampleFormat::DsdU32 => {
+            buffer.fill(DSD_SILENCE_BYTE)
+        }
     }
 }
 
@@ -1344,6 +1353,15 @@ fn sample_format_to_alsa_format(
         SampleFormat::F64 => (Format::Float64LE, Format::Float64BE),
         #[cfg(target_endian = "big")]
         SampleFormat::F64 => (Format::Float64BE, Format::Float64LE),
+        SampleFormat::DsdU8 => return Ok(Format::DSDU8),
+        #[cfg(target_endian = "little")]
+        SampleFormat::DsdU16 => (Format::DSDU16LE, Format::DSDU16BE),
+        #[cfg(target_endian = "big")]
+        SampleFormat::DsdU16 => (Format::DSDU16BE, Format::DSDU16LE),
+        #[cfg(target_endian = "little")]
+        SampleFormat::DsdU32 => (Format::DSDU32LE, Format::DSDU32BE),
+        #[cfg(target_endian = "big")]
+        SampleFormat::DsdU32 => (Format::DSDU32BE, Format::DSDU32LE),
         _ => {
             return Err(BackendSpecificError {
                 description: format!("Sample format '{sample_format}' is not supported"),

src/lib.rs

@@ -1002,7 +1002,7 @@ impl From<SupportedStreamConfig> for StreamConfig {
 #[allow(dead_code)]
 pub(crate) const COMMON_SAMPLE_RATES: &[SampleRate] = &[
     5512, 8000, 11025, 12000, 16000, 22050, 24000, 32000, 44100, 48000, 64000, 88200, 96000,
-    176400, 192000, 352800, 384000,
+    176400, 192000, 352800, 384000, 705600, 768000, 1411200, 1536000,
 ];
 
 #[test]

src/samples_formats.rs

@@ -105,6 +105,15 @@ pub enum SampleFormat {
 
     /// `f64` with a valid range of `-1.0..=1.0` with `0.0` being the origin.
     F64,
+
+    /// DSD 1-bit stream in u8 container (8 bits = 8 DSD samples) with 0x69 being the silence byte pattern.
+    DsdU8,
+
+    /// DSD 1-bit stream in u16 container (16 bits = 16 DSD samples) with 0x69 being the silence byte pattern.
+    DsdU16,
+
+    /// DSD 1-bit stream in u32 container (32 bits = 32 DSD samples) with 0x69 being the silence byte pattern.
+    DsdU32,
 }
 
 impl SampleFormat {
@@ -129,6 +138,9 @@ impl SampleFormat {
             SampleFormat::U64 => mem::size_of::<u64>(),
             SampleFormat::F32 => mem::size_of::<f32>(),
             SampleFormat::F64 => mem::size_of::<f64>(),
+            SampleFormat::DsdU8 => mem::size_of::<u8>(),
+            SampleFormat::DsdU16 => mem::size_of::<u16>(),
+            SampleFormat::DsdU32 => mem::size_of::<u32>(),
         }
     }
 
@@ -153,6 +165,7 @@ impl SampleFormat {
             SampleFormat::U64 => u64::BITS,
             SampleFormat::F32 => 32,
             SampleFormat::F64 => 64,
+            SampleFormat::DsdU8 | SampleFormat::DsdU16 | SampleFormat::DsdU32 => 1,
         }
     }
 
@@ -189,6 +202,15 @@ impl SampleFormat {
     pub fn is_float(&self) -> bool {
         matches!(*self, SampleFormat::F32 | SampleFormat::F64)
     }
+
+    #[inline]
+    #[must_use]
+    pub fn is_dsd(&self) -> bool {
+        matches!(
+            *self,
+            SampleFormat::DsdU8 | SampleFormat::DsdU16 | SampleFormat::DsdU32
+        )
+    }
 }
 
 impl Display for SampleFormat {
@@ -208,6 +230,9 @@ impl Display for SampleFormat {
             SampleFormat::U64 => "u64",
             SampleFormat::F32 => "f32",
             SampleFormat::F64 => "f64",
+            SampleFormat::DsdU8 => "dsdu8",
+            SampleFormat::DsdU16 => "dsdu16",
+            SampleFormat::DsdU32 => "dsdu32",
         }
         .fmt(f)
     }