Try to handle EAGAIN from avcodec_send_packet() properly.

The docs say on EAGAIN we should call avcodec_receive_frame()
and then re-send the same packet again.  This should do that.

This is a fix for errors trigged by the accompanying test.

1 files changed, 22 insertions, 16 deletions

diff --git a/src/lib/ffmpeg_decoder.cc b/src/lib/ffmpeg_decoder.cc
index b2a1bbbe0..d49878217 100644
--- a/src/lib/ffmpeg_decoder.cc
+++ b/src/lib/ffmpeg_decoder.cc
@@ -533,24 +533,30 @@ FFmpegDecoder::decode_and_process_video_packet (AVPacket* packet)
 
 	auto context = video_codec_context();
 
-	int r = avcodec_send_packet (context, packet);
-	if (r < 0) {
-		LOG_WARNING("avcodec_send_packet returned %1 for a video packet", r);
-	}
-
-	while (true) {
-		r = avcodec_receive_frame (context, _video_frame);
-		if (r == AVERROR(EAGAIN) || r == AVERROR_EOF || (r < 0 && !packet)) {
-			/* More input is required, no more frames are coming, or we are flushing and there was
-			 * some error which we just want to ignore.
-			 */
-			return false;
-		} else if (r < 0) {
-			throw DecodeError (N_("avcodec_receive_frame"), N_("FFmpeg::decode_and_process_video_packet"), r);
+	bool pending = false;
+	do {
+		int r = avcodec_send_packet (context, packet);
+		if (r < 0) {
+			LOG_WARNING("avcodec_send_packet returned %1 for a video packet", r);
 		}
 
-		process_video_frame ();
-	}
+		/* EAGAIN means we should call avcodec_receive_frame and then re-send the same packet */
+		pending = r == AVERROR(EAGAIN);
+
+		while (true) {
+			r = avcodec_receive_frame (context, _video_frame);
+			if (r == AVERROR(EAGAIN) || r == AVERROR_EOF || (r < 0 && !packet)) {
+				/* More input is required, no more frames are coming, or we are flushing and there was
+				 * some error which we just want to ignore.
+				 */
+				return false;
+			} else if (r < 0) {
+				throw DecodeError (N_("avcodec_receive_frame"), N_("FFmpeg::decode_and_process_video_packet"), r);
+			}
+
+			process_video_frame ();
+		}
+	} while (pending);
 
 	return true;
 }