Fix writer to skip packets with an empty payload

[bhbs]

Fixes #634

References

Similar implementation in webrtc-rs/webrtc

webrtc/media/src/io/h264_writer/mod.rs

Lines 52 to 54 in a97d49e

	if packet.payload.is_empty() {
	return Ok(());
	}

Related PR in pion/webrtc

• Fix panic in save to disk example pion/webrtc#1995

Test

1. Open https://jsfiddle.net/vfmcg8rk/1/
2. Copy SDP
3. cargo build --example save-to-disk-h264
4. echo $BROWSER_SDP | ./target/debug/examples/save-to-disk-h264 --video ./output.h264 --audio ./output.ogg
5. Start session

-> OggWriter and IvfWriter works continuously

[rainliu]

Could you fix failed tests?

[bhbs]

I’ve fixed the test! Please take a look 👍