init

src/resample.rs

@@ -0,0 +1,75 @@
+use crate::get_ffmpeg_error_msg;
+use crate::return_ffmpeg_error;
+use anyhow::Error;
+use ffmpeg_sys_the_third::{
+    av_channel_layout_default, av_frame_alloc, av_frame_copy_props, av_frame_free,
+    swr_alloc_set_opts2, swr_convert_frame, swr_init, AVChannelLayout, AVFrame, AVSampleFormat,
+    SwrContext,
+};
+use libc::malloc;
+use std::mem::transmute;
+use std::ptr;
+
+pub struct Resample {
+    format: AVSampleFormat,
+    sample_rate: u32,
+    channels: usize,
+    ctx: *mut SwrContext,
+}
+
+impl Resample {
+    pub fn new(format: AVSampleFormat, rate: u32, channels: usize) -> Self {
+        Self {
+            format,
+            channels,
+            sample_rate: rate,
+            ctx: ptr::null_mut(),
+        }
+    }
+
+    unsafe fn setup_swr(&mut self, frame: *mut AVFrame) -> Result<(), Error> {
+        if !self.ctx.is_null() {
+            return Ok(());
+        }
+        let layout = malloc(size_of::<AVChannelLayout>()) as *mut AVChannelLayout;
+        av_channel_layout_default(layout, self.channels as libc::c_int);
+
+        let ret = swr_alloc_set_opts2(
+            &mut self.ctx,
+            layout,
+            self.format,
+            self.sample_rate as libc::c_int,
+            &(*frame).ch_layout,
+            transmute((*frame).format),
+            (*frame).sample_rate,
+            0,
+            ptr::null_mut(),
+        );
+        return_ffmpeg_error!(ret);
+
+        let ret = swr_init(self.ctx);
+        return_ffmpeg_error!(ret);
+
+        Ok(())
+    }
+
+    pub unsafe fn process_frame(&mut self, frame: *mut AVFrame) -> Result<*mut AVFrame, Error> {
+        self.setup_swr(frame)?;
+
+        let mut out_frame = av_frame_alloc();
+        av_frame_copy_props(out_frame, frame);
+        (*out_frame).sample_rate = self.sample_rate as libc::c_int;
+        (*out_frame).format = transmute(self.format);
+        (*out_frame).time_base = (*frame).time_base;
+
+        av_channel_layout_default(&mut (*out_frame).ch_layout, self.channels as libc::c_int);
+
+        let ret = swr_convert_frame(self.ctx, out_frame, frame);
+        if ret < 0 {
+            av_frame_free(&mut out_frame);
+            return Err(Error::msg(get_ffmpeg_error_msg(ret)));
+        }
+
+        Ok(out_frame)
+    }
+}