Struct Mf4Writer 

pub struct Mf4Writer { /* private fields */ }

An MF4 file under construction.

Channel groups can each have their own data group (via Mf4Writer::add_group) or share a data group with sibling groups (via Mf4Writer::add_group_in), with their records sorted by time.

Implementations

impl Mf4Writer

pub fn new() -> Self

A new, empty file, stamped with the current time as its start time.

pub fn with_start_time_ns(start_time_ns: i64) -> Self

A new, empty file with an explicit start time, in nanoseconds since the Unix epoch. Deterministic output for tests, and for re-exporting a file under its original timestamp.

pub fn set_compression(&mut self, on: bool)

Whether to deflate each group’s records into a ##DZ block.

Off by default. Compression costs write time and makes the file opaque to anything that reads bytes rather than blocks; it is worth it for the long, slowly-varying channels a logger produces, and rarely worth it for a handful of samples.

pub fn set_codec(&mut self, codec: WriteCodec)

Sets the compression codec to use when compression is enabled.

pub fn codec(&self) -> WriteCodec

Returns the configured compression codec.

pub fn add_group(&mut self, times: &[f64]) -> Result<&mut WriteGroup>

Adds a channel group sampled at times (seconds). The records are sorted by time on write, so times need not be ordered — but every timestamp must be orderable, and NaN is not.

pub fn add_group_in( &mut self, sibling: usize, times: &[f64], ) -> Result<&mut WriteGroup>

Adds a channel group that shares a data group with sibling, so their records interleave behind a record ID.

pub fn start_time_ns(&self) -> i64

Returns the start time of the measurement in nanoseconds since the Unix epoch.

pub fn set_start_time_ns(&mut self, start_time_ns: i64)

Sets the start time of the measurement in nanoseconds since the Unix epoch.

pub fn is_compressed(&self) -> bool

Returns true if data blocks are configured to be deflated.

pub fn groups(&self) -> &[WriteGroup]

Returns an immutable slice of channel groups in the file.

pub fn groups_mut(&mut self) -> &mut [WriteGroup]

Returns a mutable slice of channel groups in the file.

pub fn group(&self, index: usize) -> Option<&WriteGroup>

Returns a reference to the group at index, or None if out of bounds.

pub fn group_mut(&mut self, index: usize) -> Option<&mut WriteGroup>

Returns a mutable reference to the group at index, or None if out of bounds.

pub fn remove_group(&mut self, index: usize) -> WriteGroup

Removes and returns the group at index.

pub fn retain_groups<F: FnMut(&WriteGroup) -> bool>(&mut self, f: F)

Retains only the groups specified by the predicate.

pub fn from_file(file: &Mf4File) -> Result<Self>

Imports editable data, logging every omission. Use Self::from_file_with_report for a machine-readable report or strict preservation. An unusable present master is never replaced by indices.

pub fn from_file_with_report( file: &Mf4File, mode: RewriteMode, ) -> Result<(Self, RewriteReport)>

Imports supported typed data, raw conversions, units and invalidation, reporting every omitted channel and metadata item. Strict mode returns an error if the report is nonempty, so callers cannot accidentally save a partially preserved file. No output file is created by this method.

pub fn write<W: Write>(&self, out: &mut W) -> Result<()>

Writes the file to out.

pub fn write_to_file<P: AsRef<Path>>(&self, path: P) -> Result<()>

Writes the file to a path, creating or truncating it.

Trait Implementations

impl Debug for Mf4Writer

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Mf4Writer

fn default() -> Self

Returns the “default value” for a type.