Ffmpeg 0.11 (LIBAVCODEC_VERSION_MAJOR = 54) removed the CH_LAYOUT_* aliases for
the AV_CH_LAYOUT_* defines.

diff -pru alsa-plugins-1.0.25-original/a52/pcm_a52.c alsa-plugins-1.0.25-for-ffmpeg-0.11/a52/pcm_a52.c
--- alsa-plugins-1.0.25-original/a52/pcm_a52.c	2012-01-25 08:57:07.000000000 +0100
+++ alsa-plugins-1.0.25-for-ffmpeg-0.11/a52/pcm_a52.c	2012-06-01 14:59:47.096671464 +0200
@@ -441,7 +441,21 @@ static int a52_prepare(snd_pcm_ioplug_t
 #else
   rec->avctx->sample_fmt = SAMPLE_FMT_S16;
 #endif
-#if LIBAVCODEC_VERSION_MAJOR > 52 || (LIBAVCODEC_VERSION_MAJOR == 52 && LIBAVCODEC_VERSION_MINOR >= 3)
+#if (LIBAVCODEC_VERSION_MAJOR >= 54)
+	switch (io->channels) {
+	case 2:
+		rec->avctx->channel_layout = AV_CH_LAYOUT_STEREO;
+		break;
+	case 4:
+		rec->avctx->channel_layout = AV_CH_LAYOUT_QUAD;
+		break;
+	case 6:
+		rec->avctx->channel_layout = AV_CH_LAYOUT_5POINT1;
+		break;
+	default:
+		break;
+	}
+#elif (LIBAVCODEC_VERSION_MAJOR > 52 && LIBAVCODEC_VERSION_MAJOR < 54) || (LIBAVCODEC_VERSION_MAJOR == 52 && LIBAVCODEC_VERSION_MINOR >= 3)
	switch (io->channels) {
	case 2:
		rec->avctx->channel_layout = CH_LAYOUT_STEREO;
diff -u -r alsa-plugins-1.0.25/a52/pcm_a52.c alsa-plugins-1.0.25-ffmpeg/a52/pcm_a52.c
--- alsa-plugins-1.0.25/a52/pcm_a52.c	2012-01-25 08:57:07.000000000 +0100
+++ alsa-plugins-1.0.25-ffmpeg/a52/pcm_a52.c	2012-06-09 00:42:52.177219012 +0200
@@ -702,7 +702,6 @@
	rec->channels = channels;
	rec->format = format;

-	avcodec_init();
	avcodec_register_all();

	rec->codec = avcodec_find_encoder_by_name("ac3_fixed");