Supports more audio formats (#1628)

* Supports more audio formats

* Simplify the handling of the different buffer types.

* Check the sample rate.

---------

Co-authored-by: laurent <laurent.mazare@gmail.com>

candle-examples/examples/whisper/pcm_decode.rs

@@ -0,0 +1,74 @@
+use symphonia::core::audio::{AudioBufferRef, Signal};
+use symphonia::core::codecs::{DecoderOptions, CODEC_TYPE_NULL};
+use symphonia::core::conv::FromSample;
+
+fn conv<T>(samples: &mut Vec<f32>, data: std::borrow::Cow<symphonia::core::audio::AudioBuffer<T>>)
+where
+    T: symphonia::core::sample::Sample,
+    f32: symphonia::core::conv::FromSample<T>,
+{
+    samples.extend(data.chan(0).iter().map(|v| f32::from_sample(*v)))
+}
+
+pub(crate) fn pcm_decode<P: AsRef<std::path::Path>>(path: P) -> anyhow::Result<(Vec<f32>, u32)> {
+    // Open the media source.
+    let src = std::fs::File::open(path)?;
+
+    // Create the media source stream.
+    let mss = symphonia::core::io::MediaSourceStream::new(Box::new(src), Default::default());
+
+    // Create a probe hint using the file's extension. [Optional]
+    let hint = symphonia::core::probe::Hint::new();
+
+    // Use the default options for metadata and format readers.
+    let meta_opts: symphonia::core::meta::MetadataOptions = Default::default();
+    let fmt_opts: symphonia::core::formats::FormatOptions = Default::default();
+
+    // Probe the media source.
+    let probed = symphonia::default::get_probe().format(&hint, mss, &fmt_opts, &meta_opts)?;
+    // Get the instantiated format reader.
+    let mut format = probed.format;
+
+    // Find the first audio track with a known (decodeable) codec.
+    let track = format
+        .tracks()
+        .iter()
+        .find(|t| t.codec_params.codec != CODEC_TYPE_NULL)
+        .expect("no supported audio tracks");
+
+    // Use the default options for the decoder.
+    let dec_opts: DecoderOptions = Default::default();
+
+    // Create a decoder for the track.
+    let mut decoder = symphonia::default::get_codecs()
+        .make(&track.codec_params, &dec_opts)
+        .expect("unsupported codec");
+    let track_id = track.id;
+    let sample_rate = track.codec_params.sample_rate.unwrap_or(0);
+    let mut pcm_data = Vec::new();
+    // The decode loop.
+    while let Ok(packet) = format.next_packet() {
+        // Consume any new metadata that has been read since the last packet.
+        while !format.metadata().is_latest() {
+            format.metadata().pop();
+        }
+
+        // If the packet does not belong to the selected track, skip over it.
+        if packet.track_id() != track_id {
+            continue;
+        }
+        match decoder.decode(&packet)? {
+            AudioBufferRef::F32(buf) => pcm_data.extend(buf.chan(0)),
+            AudioBufferRef::U8(data) => conv(&mut pcm_data, data),
+            AudioBufferRef::U16(data) => conv(&mut pcm_data, data),
+            AudioBufferRef::U24(data) => conv(&mut pcm_data, data),
+            AudioBufferRef::U32(data) => conv(&mut pcm_data, data),
+            AudioBufferRef::S8(data) => conv(&mut pcm_data, data),
+            AudioBufferRef::S16(data) => conv(&mut pcm_data, data),
+            AudioBufferRef::S24(data) => conv(&mut pcm_data, data),
+            AudioBufferRef::S32(data) => conv(&mut pcm_data, data),
+            AudioBufferRef::F64(data) => conv(&mut pcm_data, data),
+        }
+    }
+    Ok((pcm_data, sample_rate))
+}