init

src/scale.rs

@@ -0,0 +1,95 @@
+use crate::get_ffmpeg_error_msg;
+use std::mem::transmute;
+use std::ptr;
+
+use crate::return_ffmpeg_error;
+use anyhow::Error;
+use ffmpeg_sys_the_third::{
+    av_frame_alloc, av_frame_copy_props, sws_freeContext, sws_getContext, sws_scale_frame, AVFrame,
+    AVPixelFormat, SwsContext, SWS_BILINEAR,
+};
+
+pub struct Scaler {
+    width: u16,
+    height: u16,
+    format: AVPixelFormat,
+    ctx: *mut SwsContext,
+}
+
+unsafe impl Send for Scaler {}
+
+unsafe impl Sync for Scaler {}
+
+impl Drop for Scaler {
+    fn drop(&mut self) {
+        unsafe {
+            sws_freeContext(self.ctx);
+            self.ctx = ptr::null_mut();
+        }
+    }
+}
+
+impl Scaler {
+    pub fn new(format: AVPixelFormat) -> Self {
+        Self {
+            width: 0,
+            height: 0,
+            format,
+            ctx: ptr::null_mut(),
+        }
+    }
+
+    unsafe fn setup_scaler(
+        &mut self,
+        frame: *const AVFrame,
+        width: u16,
+        height: u16,
+    ) -> Result<(), Error> {
+        if !self.ctx.is_null() && self.width == width && self.height == height {
+            return Ok(());
+        }
+
+        // clear previous context, before re-creating
+        if !self.ctx.is_null() {
+            sws_freeContext(self.ctx);
+            self.ctx = ptr::null_mut();
+        }
+
+        self.width = width;
+        self.height = height;
+        self.ctx = sws_getContext(
+            (*frame).width,
+            (*frame).height,
+            transmute((*frame).format),
+            self.width as libc::c_int,
+            self.height as libc::c_int,
+            transmute(self.format),
+            SWS_BILINEAR,
+            ptr::null_mut(),
+            ptr::null_mut(),
+            ptr::null_mut(),
+        );
+        if self.ctx.is_null() {
+            return Err(Error::msg("Failed to create scalar context"));
+        }
+        Ok(())
+    }
+
+    pub unsafe fn process_frame(
+        &mut self,
+        frame: *mut AVFrame,
+        width: u16,
+        height: u16,
+    ) -> Result<*mut AVFrame, Error> {
+        self.setup_scaler(frame, width, height)?;
+
+        let dst_frame = av_frame_alloc();
+        let ret = av_frame_copy_props(dst_frame, frame);
+        return_ffmpeg_error!(ret);
+
+        let ret = sws_scale_frame(self.ctx, dst_frame, frame);
+        return_ffmpeg_error!(ret);
+
+        Ok(dst_frame)
+    }
+}