From 2f869884baa4f7487196fc73922437effa7c5d71 Mon Sep 17 00:00:00 2001
From: Johns <johns98@gmx.net>
Date: Tue, 21 Feb 2012 22:24:28 +0100
Subject: [PATCH] Support downmix of AC-3 to stero.

---
 ChangeLog        |  1 +
 README.txt       |  5 +++++
 codec.c          | 21 ++++++++++++++++++---
 softhddevice.cpp | 12 ++++++++++++
 4 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index e689e71..42eaf5c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,7 @@
 User johns
 Date:
 
+    Support downmix of AC-3 to stero.
     New audio PES packet parser.
     Fix bug: Grabbing a JPG image fails while suspended.
     Add support for hot keys.
diff --git a/README.txt b/README.txt
index 3098f4b..1c7b803 100644
--- a/README.txt
+++ b/README.txt
@@ -139,12 +139,17 @@ Setup: /etc/vdr/setup.conf
 
 	softhddevice.AudioDelay = 0
 	+n or -n ms
+	delay audio or delay video
 
 	softhddevice.AudioPassthrough = 0
 	0 = none, 1 = AC-3
 
 	for AC-3 the pass-through device is used.
 
+	softhddevice.AudioDownmix = 0
+	0 = none, 1 = downmix
+	downmix AC-3 to stero.
+
 	softhddevice.AutoCrop.Interval = 0
 	0 disables auto-crop
 	n each 'n' frames auto-crop is checked.
diff --git a/codec.c b/codec.c
index 8a23207..ed9d858 100644
--- a/codec.c
+++ b/codec.c
@@ -628,6 +628,7 @@ static char CodecPassthroughAC3;	///< pass ac3 through
 
 static const int CodecPassthroughAC3 = 0;
 #endif
+static char CodecDownmix;		///< enable ac-3 downmix
 
 /**
 **	Allocate a new audio decoder context.
@@ -678,6 +679,12 @@ void CodecAudioOpen(AudioDecoder * audio_decoder, const char *name,
     if (!(audio_decoder->AudioCtx = avcodec_alloc_context3(audio_codec))) {
 	Fatal(_("codec: can't allocate audio codec context\n"));
     }
+
+    if (CodecDownmix) {
+	audio_decoder->AudioCtx->request_channels = 2;
+	audio_decoder->AudioCtx->request_channel_layout =
+	    AV_CH_LAYOUT_STEREO_DOWNMIX;
+    }
     pthread_mutex_lock(&CodecLockMutex);
     // open codec
 #if LIBAVCODEC_VERSION_INT <= AV_VERSION_INT(53,5,0)
@@ -748,6 +755,16 @@ void CodecSetAudioPassthrough(int mask)
     (void)mask;
 }
 
+/**
+**	Set audio downmix.
+**
+**	@param onoff	enable/disable downmix.
+*/
+void CodecSetAudioDownmix(int onoff)
+{
+    CodecDownmix = onoff;
+}
+
 /**
 **	Reorder audio frame.
 **
@@ -889,7 +906,6 @@ void CodecAudioDecodeOld(AudioDecoder * audio_decoder, const AVPacket * avpkt)
 
 		audio_decoder->PassthroughAC3 = CodecPassthroughAC3;
 		// FIXME: use swr_convert from swresample (only in ffmpeg!)
-		// FIXME: tell ac3 decoder to use downmix
 		if (audio_decoder->ReSample) {
 		    audio_resample_close(audio_decoder->ReSample);
 		    audio_decoder->ReSample = NULL;
@@ -1089,7 +1105,7 @@ void CodecAudioDecode(AudioDecoder * audio_decoder, const AVPacket * avpkt)
 	int buf_sz;
 
 	buf_sz = sizeof(buf);
-	l = avcodec_decode_audio3(audio_ctx, buf, &buf_sz, (AVPacket *)avpkt);
+	l = avcodec_decode_audio3(audio_ctx, buf, &buf_sz, (AVPacket *) avpkt);
 	if (l == AVERROR(EAGAIN)) {
 	    Error(_("codec: latm\n"));
 	    break;
@@ -1118,7 +1134,6 @@ void CodecAudioDecode(AudioDecoder * audio_decoder, const AVPacket * avpkt)
 
 	    audio_decoder->PassthroughAC3 = CodecPassthroughAC3;
 	    // FIXME: use swr_convert from swresample (only in ffmpeg!)
-	    // FIXME: tell ac3 decoder to use downmix
 	    if (audio_decoder->ReSample) {
 		audio_resample_close(audio_decoder->ReSample);
 		audio_decoder->ReSample = NULL;
diff --git a/softhddevice.cpp b/softhddevice.cpp
index 962d8d1..5b9c1e7 100644
--- a/softhddevice.cpp
+++ b/softhddevice.cpp
@@ -38,6 +38,7 @@ extern "C"
 #include "video.h"
     extern void AudioPoller(void);
     extern void CodecSetAudioPassthrough(int);
+    extern void CodecSetAudioDownmix(int);
 }
 
 //////////////////////////////////////////////////////////////////////////////
@@ -84,6 +85,7 @@ static int ConfigVideoScaling[RESOLUTIONS];
 
 static int ConfigVideoAudioDelay;	///< config audio delay
 static int ConfigAudioPassthrough;	///< config audio pass-through
+static int ConfigAudioDownmix;		///< config audio downmix
 
 static int ConfigAutoCropInterval;	///< auto crop detection interval
 static int ConfigAutoCropDelay;		///< auto crop detection delay
@@ -414,6 +416,7 @@ class cMenuSetupSoft:public cMenuSetupPage
     int Sharpen[RESOLUTIONS];
     int AudioDelay;
     int AudioPassthrough;
+    int AudioDownmix;
     int AutoCropInterval;
     int AutoCropDelay;
     int AutoCropTolerance;
@@ -511,6 +514,9 @@ cMenuSetupSoft::cMenuSetupSoft(void)
     AudioPassthrough = ConfigAudioPassthrough;
     Add(new cMenuEditStraItem(tr("Audio pass-through"), &AudioPassthrough, 2,
 	    passthrough));
+    AudioDownmix = ConfigAudioDownmix;
+    Add(new cMenuEditBoolItem(tr("Enable AC-3 downmix"), &AudioDownmix,
+	    trVDR("no"), trVDR("yes")));
     //
     //	auto-crop
     //
@@ -581,6 +587,8 @@ void cMenuSetupSoft::Store(void)
     VideoSetAudioDelay(ConfigVideoAudioDelay);
     SetupStore("AudioPassthrough", ConfigAudioPassthrough = AudioPassthrough);
     CodecSetAudioPassthrough(ConfigAudioPassthrough);
+    SetupStore("AudioDownmix", ConfigAudioDownmix = AudioDownmix);
+    CodecSetAudioDownmix(ConfigAudioDownmix);
 
     SetupStore("AutoCrop.Interval", ConfigAutoCropInterval = AutoCropInterval);
     SetupStore("AutoCrop.Delay", ConfigAutoCropDelay = AutoCropDelay);
@@ -1527,6 +1535,10 @@ bool cPluginSoftHdDevice::SetupParse(const char *name, const char *value)
 	CodecSetAudioPassthrough(ConfigAudioPassthrough = atoi(value));
 	return true;
     }
+    if (!strcmp(name, "AudioDownmix")) {
+	CodecSetAudioDownmix(ConfigAudioDownmix = atoi(value));
+	return true;
+    }
 
     if (!strcmp(name, "AutoCrop.Interval")) {
 	VideoSetAutoCrop(ConfigAutoCropInterval =