codec/decoder/audio: impl Iterator for Audio::decode

examples/transcode-audio.rs

@@ -123,24 +123,25 @@ fn main() {
 	let in_time_base  = transcoder.decoder.time_base();
 	let out_time_base = octx.stream(0).unwrap().time_base();
 
-	let mut decoded = frame::Audio::empty();
 	let mut encoded = ffmpeg::Packet::empty();
 
 	for (stream, mut packet) in ictx.packets() {
 		if stream.index() == transcoder.stream {
 			packet.rescale_ts(stream.time_base(), in_time_base);
 
-			if let Ok(true) = transcoder.decoder.decode(&packet, &mut decoded) {
-				let timestamp = decoded.timestamp();
-				decoded.set_pts(timestamp);
+			for decoded in transcoder.decoder.decode_iter(&packet) {
+				if let Ok(Some(mut decoded)) = decoded {
+					let timestamp = decoded.timestamp();
+					decoded.set_pts(timestamp);
 
-				transcoder.filter.get("in").unwrap().source().add(&decoded).unwrap();
+					transcoder.filter.get("in").unwrap().source().add(&decoded).unwrap();
 
-				while let Ok(..) = transcoder.filter.get("out").unwrap().sink().frame(&mut decoded) {
-					if let Ok(true) = transcoder.encoder.encode(&decoded, &mut encoded) {
-						encoded.set_stream(0);
-						encoded.rescale_ts(in_time_base, out_time_base);
-						encoded.write_interleaved(&mut octx).unwrap();
+					while let Ok(..) = transcoder.filter.get("out").unwrap().sink().frame(&mut decoded) {
+						if let Ok(true) = transcoder.encoder.encode(&decoded, &mut encoded) {
+							encoded.set_stream(0);
+							encoded.rescale_ts(in_time_base, out_time_base);
+							encoded.write_interleaved(&mut octx).unwrap();
+						}
 					}
 				}
 			}
@@ -149,6 +150,8 @@ fn main() {
 
 	transcoder.filter.get("in").unwrap().source().flush().unwrap();
 
+	let mut decoded = frame::Audio::empty();
+
 	while let Ok(..) = transcoder.filter.get("out").unwrap().sink().frame(&mut decoded) {
 		if let Ok(true) = transcoder.encoder.encode(&decoded, &mut encoded) {
 			encoded.set_stream(0);

src/codec/decoder/audio.rs

@@ -1,10 +1,12 @@
+use std::{mem, ptr};
 use std::ops::{Deref, DerefMut};
 
 use libc::c_int;
 use ffi::*;
 
 use super::Opened;
-use ::{packet, Error, AudioService, ChannelLayout};
+use ::{Error, AudioService, ChannelLayout};
+use ::packet::{self, Ref};
 use ::frame;
 use ::util::format;
 use ::codec::Context;
@@ -23,6 +25,10 @@ impl Audio {
 		}
 	}
 
+	pub fn decode_iter<'a, 'b>(&'a mut self, packet: &'b packet::Packet) -> AudioFrameIter<'a, 'b> {
+		AudioFrameIter::new(self, packet)
+	}
+
 	pub fn rate(&self) -> u32 {
 		unsafe {
 			(*self.as_ptr()).sample_rate as u32
@@ -130,3 +136,57 @@ impl AsMut<Context> for Audio {
 		&mut self.0
 	}
 }
+
+pub struct AudioFrameIter<'a, 'b> {
+	audio: &'a mut Audio,
+	_packet: &'b packet::Packet,
+	avpkt: AVPacket,
+	frame: frame::Audio,
+}
+
+impl<'a, 'b> AudioFrameIter<'a, 'b> {
+	fn new(audio: &'a mut Audio, packet: &'b packet::Packet) -> AudioFrameIter<'a, 'b> {
+		let avpkt = unsafe {
+			let mut avpkt: AVPacket = mem::zeroed();
+			ptr::copy(packet.as_ptr(), (&mut avpkt) as *mut AVPacket, 1);
+			avpkt
+		};
+
+		AudioFrameIter {
+			audio: audio,
+			_packet: packet,
+			avpkt: avpkt,
+			frame: frame::Audio::empty(),
+		}
+	}
+}
+
+impl<'a, 'b> Iterator for AudioFrameIter<'a, 'b> {
+    type Item = Result<Option<frame::Audio>, Error>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+		let avpkt = &mut self.avpkt;
+
+		if avpkt.size != 0 {
+			let mut got: c_int = 0;
+
+			unsafe {
+				match avcodec_decode_audio4(self.audio.as_mut_ptr(), self.frame.as_mut_ptr(), &mut got, avpkt as *const AVPacket) {
+					e if e < 0 => Some(Err(Error::from(e))),
+					n => {
+						avpkt.data = avpkt.data.offset(n as isize);
+						avpkt.size -= n;
+
+						if got != 0 {
+							Some(Ok(Some(frame::Audio::wrap(self.frame.as_mut_ptr()))))
+						} else {
+							Some(Ok(None))
+						}
+					}
+				}
+			}
+		} else {
+			None
+		}
+	}
+}

src/util/frame/mod.rs

@@ -182,8 +182,10 @@ impl Frame {
 impl Drop for Frame {
 	#[inline]
 	fn drop(&mut self) {
-		unsafe {
-			av_frame_free(&mut self.as_mut_ptr());
+		if self._own {
+			unsafe {
+				av_frame_free(&mut self.as_mut_ptr());
+			}
 		}
 	}
 }