symphonium 0.9.2

An unofficial easy-to-use wrapper around Symphonia for loading audio files
Documentation 
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use std::num::{NonZeroU32, NonZeroUsize};

use symphonia::core::{audio::AudioBuffer, codecs::Decoder, probe::ProbeResult};

use super::{decode_warning, shrink_buffer};
use crate::{DecodeConfig, DecodedAudioF32, error::LoadError};

pub(crate) fn decode_f32(
    probed: &mut ProbeResult,
    config: &DecodeConfig,
    num_channels: NonZeroUsize,
    sample_rate: NonZeroU32,
    original_sample_rate: NonZeroU32,
    decoder: &mut dyn Decoder,
) -> Result<DecodedAudioF32, LoadError> {
    const BYTES_PER_SAMPLE: usize = 4;

    // Get the default track in the audio stream.
    let track = probed
        .format
        .default_track()
        .ok_or_else(|| LoadError::NoTrackFound)?;

    let file_frames = track.codec_params.n_frames;
    let max_frames = config.max_bytes / (BYTES_PER_SAMPLE * num_channels.get());

    if let Some(frames) = file_frames
        && frames > max_frames as u64
    {
        return Err(LoadError::FileTooLarge(config.max_bytes));
    }

    let mut tmp_conversion_buf: Option<AudioBuffer<f32>> = None;

    let estimated_final_frames = file_frames.unwrap_or(32768) as usize;
    let mut final_buf: Vec<Vec<f32>> = (0..num_channels.get())
        .map(|_| {
            let mut v = Vec::new();
            v.reserve_exact(estimated_final_frames);
            v
        })
        .collect();

    let track_id = track.id;

    while let Ok(packet) = probed.format.next_packet() {
        // If the packet does not belong to the selected track, skip over it.
        if packet.track_id() != track_id {
            continue;
        }

        match decoder.decode(&packet) {
            Ok(decoded) => {
                // If this is the first decoded packet, allocate the temporary conversion
                // buffer with the required capacity.
                if tmp_conversion_buf.is_none() {
                    let spec = *(decoded.spec());
                    let duration = decoded.capacity();

                    tmp_conversion_buf = Some(AudioBuffer::new(duration as u64, spec));
                }
                let tmp_conversion_buf = tmp_conversion_buf.as_mut().unwrap();
                if tmp_conversion_buf.capacity() < decoded.capacity() {
                    let spec = *(decoded.spec());
                    let duration = decoded.capacity();

                    *tmp_conversion_buf = AudioBuffer::new(duration as u64, spec);
                }

                decoded.convert(tmp_conversion_buf);

                let tmp_conversion_planes = tmp_conversion_buf.planes();
                let converted_planes = tmp_conversion_planes.planes();

                for (final_ch, decoded_ch) in final_buf.iter_mut().zip(converted_planes) {
                    final_ch.extend_from_slice(decoded_ch);
                }

                if file_frames.is_none() {
                    // Protect against really large files causing out of memory errors.
                    if final_buf[0].len() > max_frames {
                        return Err(LoadError::FileTooLarge(config.max_bytes));
                    }
                }
            }
            Err(symphonia::core::errors::Error::DecodeError(err)) => decode_warning(err),
            Err(e) => return Err(LoadError::ErrorWhileDecoding(e)),
        }
    }

    shrink_buffer(&mut final_buf);

    Ok(DecodedAudioF32::new(
        final_buf,
        sample_rate,
        original_sample_rate,
    ))
}