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Introduce generic read_frames and write_frames functions

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This commit is contained in:
Ian Hobson
2023-05-12 16:52:06 +02:00
parent 7290d5ec81
commit 3400778991
10 changed files with 269 additions and 156 deletions
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131
src/wavereader.rs
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@@ -18,11 +18,13 @@ use super::fourcc::{
IXML_SIG, JUNK_SIG, LIST_SIG,
};
use super::parser::Parser;
use super::CommonFormat;
use super::{CommonFormat, Sample, I24};
use byteorder::LittleEndian;
use byteorder::ReadBytesExt;
use dasp_sample::Sample as _; // Expose to_sample()
/// Read audio frames
///
/// The inner reader is interpreted as a raw audio data
@@ -88,78 +90,79 @@ impl<R: Read + Seek> AudioFrameReader<R> {
Ok((seek_result - self.start) / self.format.block_alignment as u64)
}
/// Read a frame
/// Reads frames from the file into the provided buffer
///
/// A single frame is read from the audio stream and the read location
/// is advanced one frame.
/// The function will attempt to fill the buffer, but will stop without error when the end of
/// the file is reached.
///
/// Regardless of the number of bits in the audio sample, this method
/// always writes `i32` samples back to the buffer. These samples are
/// written back "right-aligned" so samples that are shorter than i32
/// will leave the MSB bits empty.
/// The reader will convert from the file's sample type into the buffer's sample type.
/// Note that no dithering will be applied during sample type conversion,
/// if dithering is required then it will need to be applied manually.
///
/// For example: A full-code sample in 16 bit (0xFFFF) will be written
/// back to the buffer as 0x0000FFFF.
///
///
/// ### Panics
///
/// The `buffer` must have a number of elements equal to the number of
/// channels and this method will panic if this is not the case.
pub fn read_integer_frame(&mut self, buffer: &mut [i32]) -> Result<u64, Error> {
/// The return value is the number of frames read into the buffer.
pub fn read_frames<S>(&mut self, buffer: &mut [S]) -> Result<u64, Error>
where
S: Sample,
{
use CommonFormat::*;
let channel_count = self.format.channel_count as usize;
let common_format = self.format.common_format();
let bits_per_sample = self.format.bits_per_sample;
assert!(
buffer.len() as u16 == self.format.channel_count,
"read_integer_frame was called with a mis-sized buffer, expected {}, was {}",
self.format.channel_count,
buffer.len() % channel_count == 0,
"read_frames was called with a mis-sized buffer, expected a multiple of {}, was {}",
channel_count,
buffer.len()
);
let framed_bits_per_sample = self.format.block_alignment * 8 / self.format.channel_count;
let position = self.inner.stream_position()? - self.start;
let frames_requested = (buffer.len() / channel_count) as u64;
let bytes_per_frame = self.format.block_alignment as u64;
let frames_remaining = (self.length - position) / bytes_per_frame;
let frames_to_read = frames_requested.min(frames_remaining);
let samples_to_read = frames_to_read as usize * channel_count;
let tell = self.inner.stream_position()?;
match (common_format, bits_per_sample) {
(IntegerPCM, 8) => read_into_buffer(samples_to_read, buffer, || {
Ok(self.inner.read_u8()?.to_sample())
}),
(IntegerPCM, 16) => read_into_buffer(samples_to_read, buffer, || {
Ok(self.inner.read_i16::<LittleEndian>()?.to_sample())
}),
(IntegerPCM, 24) => read_into_buffer(samples_to_read, buffer, || {
Ok(I24::from(self.inner.read_i24::<LittleEndian>()?).to_sample())
}),
(IntegerPCM, 32) => read_into_buffer(samples_to_read, buffer, || {
Ok(self.inner.read_i32::<LittleEndian>()?.to_sample())
}),
(IeeeFloatPCM, 32) => read_into_buffer(samples_to_read, buffer, || {
Ok(self.inner.read_f32::<LittleEndian>()?.to_sample())
}),
(_, _) => panic!(
"Unsupported format, bits per sample {}, channels {}, sample format: {:?}",
bits_per_sample, channel_count, common_format
),
}?;
if (tell - self.start) < self.length {
for sample in buffer.iter_mut().take(self.format.channel_count as usize) {
*sample = match (self.format.bits_per_sample, framed_bits_per_sample) {
(0..=8,8) => self.inner.read_u8()? as i32 - 0x80_i32, // EBU 3285 §A2.2
(9..=16,16) => self.inner.read_i16::<LittleEndian>()? as i32,
(10..=24,24) => self.inner.read_i24::<LittleEndian>()?,
(25..=32,32) => self.inner.read_i32::<LittleEndian>()?,
(b,_)=> panic!("Unrecognized integer format, bits per sample {}, channels {}, block_alignment {}",
b, self.format.channel_count, self.format.block_alignment)
}
}
Ok(1)
} else {
Ok(0)
}
Ok(frames_to_read)
}
}
fn read_into_buffer<S, F>(
sample_count: usize,
buffer: &mut [S],
mut read_fn: F,
) -> Result<(), Error>
where
F: FnMut() -> Result<S, Error>,
{
for output in buffer.iter_mut().take(sample_count) {
*output = read_fn()?;
}
pub fn read_float_frame(&mut self, buffer: &mut [f32]) -> Result<u64, Error> {
assert!(
buffer.len() as u16 == self.format.channel_count,
"read_float_frame was called with a mis-sized buffer, expected {}, was {}",
self.format.channel_count,
buffer.len()
);
let framed_bits_per_sample = self.format.block_alignment * 8 / self.format.channel_count;
let tell = self.inner.stream_position()?;
if (tell - self.start) < self.length {
for sample in buffer.iter_mut().take(self.format.channel_count as usize) {
*sample = match (self.format.bits_per_sample, framed_bits_per_sample) {
(25..=32,32) => self.inner.read_f32::<LittleEndian>()?,
(b,_)=> panic!("Unrecognized integer format, bits per sample {}, channels {}, block_alignment {}",
b, self.format.channel_count, self.format.block_alignment)
}
}
Ok(1)
} else {
Ok(0)
}
}
Ok(())
}
/// Wave, Broadcast-WAV and RF64/BW64 parser/reader.
@@ -173,9 +176,9 @@ impl<R: Read + Seek> AudioFrameReader<R> {
/// assert_eq!(format.channel_count, 1);
///
/// let mut frame_reader = r.audio_frame_reader().unwrap();
/// let mut buffer = format.create_frame_buffer(1);
/// let mut buffer = format.create_frame_buffer::<i32>(1);
///
/// let read = frame_reader.read_integer_frame(&mut buffer).unwrap();
/// let read = frame_reader.read_frames(&mut buffer).unwrap();
///
/// assert_eq!(buffer, [0i32]);
/// assert_eq!(read, 1);