playa-ffmpeg 8.0.3

Safe FFmpeg wrapper with vcpkg integration for simplified cross-platform builds (FFmpeg 8.0, Rust 2024)
Documentation 
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use std::ptr;

use super::Delay;
use crate::{ChannelLayout, Dictionary, Error, ffi::*, frame, util::format};
use libc::c_int;
use std::ffi::c_void;

#[derive(Eq, PartialEq, Copy, Clone)]
pub struct Definition {
    pub format: format::Sample,
    pub channel_layout: ChannelLayout,
    pub rate: u32,
}

pub struct Context {
    ptr: *mut SwrContext,

    input: Definition,
    output: Definition,
}

unsafe impl Send for Context {}

impl Context {
    #[doc(hidden)]
    pub unsafe fn as_ptr(&self) -> *const SwrContext {
        self.ptr as *const _
    }

    #[doc(hidden)]
    pub unsafe fn as_mut_ptr(&mut self) -> *mut SwrContext {
        self.ptr
    }
}

impl Context {
    /// Create a resampler with the given definitions.
    pub fn get(src_format: format::Sample, src_channel_layout: ChannelLayout, src_rate: u32, dst_format: format::Sample, dst_channel_layout: ChannelLayout, dst_rate: u32) -> Result<Self, Error> {
        Self::get_with(src_format, src_channel_layout, src_rate, dst_format, dst_channel_layout, dst_rate, Dictionary::new())
    }

    /// Create a resampler with the given definitions and custom options dictionary.
    pub fn get_with(src_format: format::Sample, src_channel_layout: ChannelLayout, src_rate: u32, dst_format: format::Sample, dst_channel_layout: ChannelLayout, dst_rate: u32, options: Dictionary) -> Result<Self, Error> {
        unsafe {
            #[allow(unused_assignments)]
            let mut ptr = std::ptr::null_mut();

            #[cfg(not(feature = "ffmpeg_7_0"))]
            {
                ptr = swr_alloc_set_opts(ptr::null_mut(), dst_channel_layout.bits() as i64, dst_format.into(), dst_rate as c_int, src_channel_layout.bits() as i64, src_format.into(), src_rate as c_int, 0, ptr::null_mut());
            }
            #[cfg(feature = "ffmpeg_7_0")]
            {
                let e = swr_alloc_set_opts2(&mut ptr, &dst_channel_layout.into(), dst_format.into(), dst_rate as c_int, &src_channel_layout.into(), src_format.into(), src_rate as c_int, 0, ptr::null_mut());
                if e != 0 {
                    return Err(Error::from(e));
                }
            }

            let mut opts = options.disown();
            let res = av_opt_set_dict(ptr as *mut c_void, &mut opts);
            Dictionary::own(opts);

            if res != 0 {
                return Err(Error::from(res));
            }

            if !ptr.is_null() {
                match swr_init(ptr) {
                    e if e < 0 => Err(Error::from(e)),

                    _ => Ok(Context { ptr, input: Definition { format: src_format, channel_layout: src_channel_layout, rate: src_rate }, output: Definition { format: dst_format, channel_layout: dst_channel_layout, rate: dst_rate } }),
                }
            } else {
                Err(Error::InvalidData)
            }
        }
    }

    /// Get the input definition.
    pub fn input(&self) -> &Definition {
        &self.input
    }

    /// Get the output definition.
    pub fn output(&self) -> &Definition {
        &self.output
    }

    /// Get the remaining delay.
    pub fn delay(&self) -> Option<Delay> {
        unsafe {
            match swr_get_delay(self.as_ptr() as *mut _, 1) {
                0 => None,
                _ => Some(Delay::from(self)),
            }
        }
    }

    /// Run the resampler from the given input to the given output.
    ///
    /// When there are internal frames to process it will return `Ok(Some(Delay { .. }))`.
    pub fn run(&mut self, input: &frame::Audio, output: &mut frame::Audio) -> Result<Option<Delay>, Error> {
        unsafe {
            (*output.as_mut_ptr()).sample_rate = self.output.rate as i32;
        }

        unsafe {
            if output.is_empty() {
                output.alloc(self.output.format, input.samples(), self.output.channel_layout);
            }

            match swr_convert_frame(self.as_mut_ptr(), output.as_mut_ptr(), input.as_ptr()) {
                0 => Ok(self.delay()),

                e => Err(Error::from(e)),
            }
        }
    }

    /// Convert one of the remaining internal frames.
    ///
    /// When there are no more internal frames `Ok(None)` will be returned.
    pub fn flush(&mut self, output: &mut frame::Audio) -> Result<Option<Delay>, Error> {
        unsafe {
            (*output.as_mut_ptr()).sample_rate = self.output.rate as i32;
        }

        unsafe {
            match swr_convert_frame(self.as_mut_ptr(), output.as_mut_ptr(), ptr::null()) {
                0 => Ok(self.delay()),

                e => Err(Error::from(e)),
            }
        }
    }
}

impl Drop for Context {
    fn drop(&mut self) {
        unsafe {
            swr_free(&mut self.as_mut_ptr());
        }
    }
}