Changed convert_stereo_to_mono_audio to return a Result

examples/audio_transcription.rs

@@ -7,7 +7,7 @@ use std::io::Write;
 use whisper_rs::{FullParams, SamplingStrategy, WhisperContext};
 
 /// Loads a context and model, processes an audio file, and prints the resulting transcript to stdout.
-fn main() {
+fn main() -> Result<(), &'static str> {
     // Load a context and model.
     let mut ctx = WhisperContext::new("example/path/to/model/whisper.cpp/models/ggml-base.en.bin")
         .expect("failed to load model");
@@ -52,7 +52,7 @@ fn main() {
     // These utilities are provided for convenience, but can be replaced with custom conversion logic.
     // SIMD variants of these functions are also available on nightly Rust (see the docs).
     if channels == 2 {
-        audio = whisper_rs::convert_stereo_to_mono_audio(&audio);
+        audio = whisper_rs::convert_stereo_to_mono_audio(&audio)?;
     } else if channels != 1 {
         panic!(">2 channels unsupported");
     }
@@ -85,4 +85,5 @@ fn main() {
         file.write_all(line.as_bytes())
             .expect("failed to write to file");
     }
+    Ok(())
 }

examples/basic_use.rs

@@ -5,7 +5,7 @@ use whisper_rs::{FullParams, SamplingStrategy, WhisperContext};
 // note that running this example will not do anything, as it is just a
 // demonstration of how to use the library, and actual usage requires
 // more dependencies than the base library.
-pub fn usage() {
+pub fn usage() -> Result<(), &'static str> {
     // load a context and model
     let mut ctx = WhisperContext::new("path/to/model").expect("failed to load model");
 
@@ -38,7 +38,7 @@ pub fn usage() {
     // SIMD variants of these functions are also available, but only on nightly Rust: see the docs
     let audio_data = whisper_rs::convert_stereo_to_mono_audio(
         &whisper_rs::convert_integer_to_float_audio(&audio_data),
-    );
+    )?;
 
     // now we can run the model
     ctx.full(params, &audio_data[..])
@@ -52,6 +52,8 @@ pub fn usage() {
         let end_timestamp = ctx.full_get_segment_t1(i);
         println!("[{} - {}]: {}", start_timestamp, end_timestamp, segment);
     }
+
+    Ok(())
 }
 
 fn main() {

src/utilities.rs

@@ -54,7 +54,6 @@ pub fn convert_integer_to_float_audio_simd(samples: &[i16]) -> Vec<f32> {
 
 /// Convert 32 bit floating point stereo PCM audio to 32 bit floating point mono PCM audio.
 ///
-/// If there are an odd number of samples, the last half-sample is dropped.
 /// This variant does not use SIMD instructions.
 ///
 /// # Arguments
@@ -62,16 +61,20 @@ pub fn convert_integer_to_float_audio_simd(samples: &[i16]) -> Vec<f32> {
 ///
 /// # Returns
 /// A vector of 32 bit floating point mono PCM audio samples.
-pub fn convert_stereo_to_mono_audio(samples: &[f32]) -> Vec<f32> {
-    samples
+pub fn convert_stereo_to_mono_audio(samples: &[f32]) -> Result<Vec<f32>, &'static str> {
+    if samples.len() & 1 != 0 {
+        return Err("The stereo audio vector has an odd number of samples. \
+            This means a half-sample is missing somewhere");
+    }
+
+    Ok(samples
         .chunks_exact(2)
         .map(|x| (x[0] + x[1]) / 2.0)
-        .collect()
+        .collect())
 }
 
 /// Convert 32 bit floating point stereo PCM audio to 32 bit floating point mono PCM audio.
 ///
-/// If there are an odd number of samples, the last half-sample is dropped.
 /// This variant uses SIMD instructions, and as such is only available on
 /// nightly Rust.
 ///
@@ -81,7 +84,7 @@ pub fn convert_stereo_to_mono_audio(samples: &[f32]) -> Vec<f32> {
 /// # Returns
 /// A vector of 32 bit floating point mono PCM audio samples.
 #[cfg(feature = "simd")]
-pub fn convert_stereo_to_mono_audio_simd(samples: &[f32]) -> Vec<f32> {
+pub fn convert_stereo_to_mono_audio_simd(samples: &[f32]) -> Result<Vec<f32>, &'static str> {
     let mut mono = Vec::with_capacity(samples.len() / 2);
 
     let div_array = f32x16::splat(2.0);
@@ -105,9 +108,9 @@ pub fn convert_stereo_to_mono_audio_simd(samples: &[f32]) -> Vec<f32> {
     // Handle the remainder.
     // do this normally because it's only a few samples and the overhead of
     // converting to SIMD is not worth it.
-    mono.extend(convert_stereo_to_mono_audio(remainder));
+    mono.extend(convert_stereo_to_mono_audio(remainder)?);
 
-    mono
+    Ok(mono)
 }
 
 #[cfg(feature = "simd")]
@@ -116,12 +119,32 @@ mod test {
     use super::*;
 
     #[test]
-    pub fn assert_stereo_to_mono_simd() {
-        // fake some sample data, of 1028 elements
-        let mut samples = Vec::with_capacity(1028);
-        for i in 0..1029 {
-            samples.push(i as f32);
+    pub fn assert_stereo_to_mono_err() {
+        // fake some sample data
+        let samples = (0u16..1029).map(f32::from).collect::<Vec<f32>>();
+        let mono = convert_stereo_to_mono_audio(&samples);
+        assert!(mono.is_err());
     }
+}
+
+#[cfg(feature = "simd")]
+#[cfg(test)]
+mod test_simd {
+    use super::*;
+
+    #[test]
+    pub fn assert_stereo_to_mono_simd() {
+        // fake some sample data
+        let samples = (0u16..1028).map(f32::from).collect::<Vec<f32>>();
+        let mono_simd = convert_stereo_to_mono_audio_simd(&samples);
+        let mono = convert_stereo_to_mono_audio(&samples);
+        assert_eq!(mono_simd, mono);
+    }
+
+    #[test]
+    pub fn assert_stereo_to_mono_simd_err() {
+        // fake some sample data
+        let samples = (0u16..1029).map(f32::from).collect::<Vec<f32>>();
         let mono_simd = convert_stereo_to_mono_audio_simd(&samples);
         let mono = convert_stereo_to_mono_audio(&samples);
         assert_eq!(mono_simd, mono);