From ef6e0314b8c0930e63ef8715c8bbb504e9adae52 Mon Sep 17 00:00:00 2001
From: Thomas Reufer <thomas@reufer.ch>
Date: Mon, 29 Sep 2014 21:36:38 +0200
Subject: set HDMI speaker layout to fix channel mapping for multi channel PCM
 output

---
 HISTORY |  1 +
 audio.c |  3 +++
 setup.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 setup.h |  2 ++
 4 files changed, 49 insertions(+)

diff --git a/HISTORY b/HISTORY
index 3c15dc4..bc5f14f 100644
--- a/HISTORY
+++ b/HISTORY
@@ -2,6 +2,7 @@ VDR Plugin 'rpihddevice' Revision History
 -----------------------------------------
 
 - new:
+  - set HDMI speaker layout to fix channel mapping for multi channel PCM output
   - support building against external ffmpeg/libav by setting EXT_LIBAV
   - support for >=ffmpeg-1.2 and >=libav-0.8 with resampling
   - setup option for video framing mode in case of incompatible aspect ratio
diff --git a/audio.c b/audio.c
index 9cf9f17..c99c51b 100644
--- a/audio.c
+++ b/audio.c
@@ -1170,6 +1170,9 @@ void cRpiAudioDecoder::SetCodec(cAudioCodec::eCodec codec, unsigned int &channel
 				cRpiAudioPort::Str(outputPort), channels, cAudioCodec::Str(outputFormat),
 				samplingRate / 1000, (samplingRate % 1000) / 100,
 				m_passthrough ? " (pass-through)" : "");
+
+		if (outputPort == cRpiAudioPort::eHDMI)
+			cRpiSetup::SetHDMIChannelMapping(m_passthrough, channels);
 	}
 }
 
diff --git a/setup.c b/setup.c
index fe2cd36..711f5b9 100644
--- a/setup.c
+++ b/setup.c
@@ -226,6 +226,49 @@ int cRpiSetup::GetDisplaySize(int &width, int &height, double &aspect)
 	return 0;
 }
 
+void cRpiSetup::SetHDMIChannelMapping(bool passthrough, int channels)
+{
+	char command[80], response[80];
+
+	sprintf(command, "hdmi_stream_channels %d", passthrough ? 1 : 0);
+	vc_gencmd(response, sizeof response, command);
+
+	uint32_t channel_map = 0;
+
+	if (!passthrough && channels > 0 && channels <= 6)
+	{
+		const unsigned char ch_mapping[6][8] =
+		{
+			{ 0, 0, 0, 0, 0, 0, 0, 0 }, // not supported
+			{ 1, 2, 0, 0, 0, 0, 0, 0 }, // 2.0
+			{ 1, 2, 4, 0, 0, 0, 0, 0 }, // 2.1
+			{ 0, 0, 0, 0, 0, 0, 0, 0 }, // not supported
+			{ 0, 0, 0, 0, 0, 0, 0, 0 }, // not supported
+			{ 1, 2, 4, 3, 5, 6, 0, 0 }, // 5.1
+		};
+
+		// speaker layout according CEA 861, Table 28: Audio InfoFrame, byte 4
+		const unsigned char cea_map[] =
+		{
+			0xff,	// not supported
+			0x00,	// 2.0
+			0x01,	// 2.1
+			0xff,	// not supported
+			0xff,	// not supported
+			0x0b	// 5.1
+		};
+
+		for (int ch = 0; ch < channels; ch++)
+			if (ch_mapping[channels - 1][ch])
+				channel_map |= (ch_mapping[channels - 1][ch] - 1) << (3 * ch);
+
+		channel_map |= cea_map[channels - 1] << 24;
+	}
+
+	sprintf(command, "hdmi_channel_map 0x%08x", channel_map);
+	vc_gencmd(response, sizeof response, command);
+}
+
 cMenuSetupPage* cRpiSetup::GetSetupPage(void)
 {
 	return new cRpiSetupPage(m_audio, m_video);
diff --git a/setup.h b/setup.h
index 146fe53..d1b29c1 100644
--- a/setup.h
+++ b/setup.h
@@ -72,6 +72,8 @@ public:
 
 	static int GetDisplaySize(int &width, int &height, double &aspect);
 
+	static void SetHDMIChannelMapping(bool passthrough, int channels);
+
 	static bool IsDisplayProgressive(void) {
 		return GetInstance()->m_isProgressive; }
 
-- 
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