From b3452771c4550b46ea54d15be6cfe8cc10585199 Mon Sep 17 00:00:00 2001
From: Carl Eugen Hoyos <cehoyos@ag.or.at>
Date: Wed, 15 Jun 2011 10:57:26 +0200
Subject: [PATCH] Fix multi-channel AAC encoding.

Fixes ticket 55.
---
 libavcodec/aacenc.c  | 20 +++++++++++++++++++-
 libavcodec/libfaac.c | 10 ++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/libavcodec/aacenc.c b/libavcodec/aacenc.c
index 66af2b1915..16c59061dc 100644
--- a/libavcodec/aacenc.c
+++ b/libavcodec/aacenc.c
@@ -135,6 +135,15 @@ static const uint8_t aac_chan_configs[6][5] = {
  {4, TYPE_SCE, TYPE_CPE, TYPE_CPE, TYPE_LFE}, // 6 channels - front center + stereo + back stereo + LFE
 };
 
+static const uint8_t channel_maps[][AAC_MAX_CHANNELS] = {
+    { 0 },
+    { 0, 1 },
+    { 2, 0, 1 },
+    { 2, 0, 1, 3 },
+    { 2, 0, 1, 3, 4 },
+    { 2, 0, 1, 4, 5, 3 },
+};
+
 /**
  * Make AAC audio config object.
  * @see 1.6.2.1 "Syntax - AudioSpecificConfig"
@@ -499,15 +508,24 @@ static int aac_encode_frame(AVCodecContext *avctx,
         return 0;
     if (data) {
         if (!s->psypp) {
+            if (avctx->channels <= 2) {
             memcpy(s->samples + 1024 * avctx->channels, data,
                    1024 * avctx->channels * sizeof(s->samples[0]));
+            } else {
+                for (i = 0; i < 1024; i++)
+                    for (ch = 0; ch < avctx->channels; ch++)
+                        s->samples[(i + 1024) * avctx->channels + ch] =
+                            ((int16_t*)data)[i * avctx->channels +
+                                             channel_maps[avctx->channels-1][ch]];
+            }
         } else {
             start_ch = 0;
             samples2 = s->samples + 1024 * avctx->channels;
             for (i = 0; i < chan_map[0]; i++) {
                 tag = chan_map[i+1];
                 chans = tag == TYPE_CPE ? 2 : 1;
-                ff_psy_preprocess(s->psypp, (uint16_t*)data + start_ch,
+                ff_psy_preprocess(s->psypp,
+                                  (uint16_t*)data + channel_maps[avctx->channels-1][start_ch],
                                   samples2 + start_ch, start_ch, chans);
                 start_ch += chans;
             }
diff --git a/libavcodec/libfaac.c b/libavcodec/libfaac.c
index af85587272..2acc682581 100644
--- a/libavcodec/libfaac.c
+++ b/libavcodec/libfaac.c
@@ -31,6 +31,13 @@ typedef struct FaacAudioContext {
     faacEncHandle faac_handle;
 } FaacAudioContext;
 
+static const int channel_maps[][6] = {
+    { 2, 0, 1 },          //< C L R
+    { 2, 0, 1, 3 },       //< C L R Cs
+    { 2, 0, 1, 3, 4 },    //< C L R Ls Rs
+    { 2, 0, 1, 4, 5, 3 }, //< C L R Ls Rs LFE
+};
+
 static av_cold int Faac_encode_init(AVCodecContext *avctx)
 {
     FaacAudioContext *s = avctx->priv_data;
@@ -86,6 +93,9 @@ static av_cold int Faac_encode_init(AVCodecContext *avctx)
     }
     faac_cfg->outputFormat = 1;
     faac_cfg->inputFormat = FAAC_INPUT_16BIT;
+    if (avctx->channels > 2)
+        memcpy(faac_cfg->channel_map, channel_maps[avctx->channels-3],
+               avctx->channels * sizeof(int));
 
     avctx->frame_size = samples_input / avctx->channels;