stop frame properties from changing after starting, ffmpeg doesn't like that

examples/ffmpeg_recorder.rs

@@ -28,6 +28,7 @@ struct MyEmulator {
     video_filter: filter::Graph,
     audio_filter: filter::Graph,
     sys_path: Option<PathBuf>,
+    frame_properties_locked: bool,
 }
 
 fn video_filter(
@@ -147,6 +148,7 @@ impl MyEmulator {
             video_filter,
             audio_filter,
             sys_path: sys_path.as_ref().map(|x| x.as_ref().to_path_buf()),
+            frame_properties_locked: false,
         };
 
         let mut pin_emu = Box::pin(emu);
@@ -243,6 +245,10 @@ impl retro::wrapper::Handler for MyEmulator {
     }
 
     fn set_pixel_format(&mut self, format: PixelFormat) -> bool {
+        if self.frame_properties_locked {
+            return true;
+        }
+
         self.video_pixel_format = match format {
             PixelFormat::ARGB1555 => format::Pixel::RGB555,
             PixelFormat::ARGB8888 => format::Pixel::RGB32,
@@ -253,16 +259,26 @@ impl retro::wrapper::Handler for MyEmulator {
     }
 
     fn set_system_av_info(&mut self, system_av_info: SystemAvInfo) -> bool {
+        if self.frame_properties_locked {
+            return true;
+        }
+
         self.video_encoder.set_frame_rate(system_av_info.timing.fps.into());
+        /*
         if system_av_info.timing.sample_rate.round() as i32 > 0 {
             self.audio_encoder.set_rate(system_av_info.timing.sample_rate.round() as i32);
         }
+        */
         self.av_info.timing = system_av_info.timing;
         self.set_geometry(system_av_info.geometry);
         true
     }
 
     fn set_geometry(&mut self, geometry: GameGeometry) -> bool {
+        if self.frame_properties_locked {
+            return true;
+        }
+
         self.video_encoder.set_width(geometry.base_width);
         self.video_encoder.set_height(geometry.base_height);
         self.video_encoder.set_aspect_ratio(geometry.aspect_ratio as f64);
@@ -322,6 +338,7 @@ fn main() -> Fallible<()> {
     let mut emu = MyEmulator::new(opt.core, &opt.system, video_encoder, audio_encoder);
     emu.load_game(opt.rom);
 
+    emu.frame_properties_locked = true;
     octx.write_header().unwrap();
 
     for _ in 0..60*60 {