[LEDE-DEV] [packages for-15.05 PATCH 2/2] ffmpeg: backport AAC fix for multichannel mapping

[Rafał Miłecki]

From: Rafał Miłecki <rafal at milecki.pl>

It's a backport from 2.7 branch that fixes parsing some AAC formats.

What makes this quite important is that broken parsing was leading to
many loop iterations, scanning taking a lot of time and allocating a lot
of memory. Parsing 1.3 GB MPEG TS file could result in allocating
55+ MiB of memory causing OOM on some embedded platforms.

This is important change e.g. for minidlna users who were complaining
about slowness and memory consumption of scanning process. This problem
was forcing some users to building minidlna database on PCs and moving
ready one to the target device.

Signed-off-by: Rafał Miłecki <rafal at milecki.pl>
---
 multimedia/ffmpeg/Makefile                         |  2 +-
 ...ly-map-multichannel-ADTS-AAC-with-non-zer.patch | 68 ++++++++++++++++++++++
 2 files changed, 69 insertions(+), 1 deletion(-)
 create mode 100644 multimedia/ffmpeg/patches/050-aac-Correctly-map-multichannel-ADTS-AAC-with-non-zer.patch

diff --git a/multimedia/ffmpeg/Makefile b/multimedia/ffmpeg/Makefile
index 493f47a..4d9cf01 100644
--- a/multimedia/ffmpeg/Makefile
+++ b/multimedia/ffmpeg/Makefile
@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=ffmpeg
 PKG_VERSION:=2.6.9
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.bz2
 PKG_SOURCE_URL:=http://ffmpeg.org/releases/
diff --git a/multimedia/ffmpeg/patches/050-aac-Correctly-map-multichannel-ADTS-AAC-with-non-zer.patch b/multimedia/ffmpeg/patches/050-aac-Correctly-map-multichannel-ADTS-AAC-with-non-zer.patch
new file mode 100644
index 0000000..4ef1914
--- /dev/null
+++ b/multimedia/ffmpeg/patches/050-aac-Correctly-map-multichannel-ADTS-AAC-with-non-zer.patch
@@ -0,0 +1,68 @@
+From 0289f81241e720452b5a77713488d54d3ec252d7 Mon Sep 17 00:00:00 2001
+From: nu774 <honeycomb77 at gmail.com>
+Date: Wed, 3 Jun 2015 14:01:32 +0900
+Subject: [PATCH] aac: Correctly map multichannel ADTS AAC with non-zero
+ channel_config + PCE
+
+The decoder assigns channels using default channel configuration
+for 5.1ch when it parses an ADTS frame header using consecutive
+channel ids.
+
+When a PCE comes, it reassigns channels using PCE configuration
+using directly the ids provided. They can be arbitrary.
+
+Always use consecutive channel ids to avoid decoding glitches due
+spurious reconfigurations due the channel ids mismatch between the
+two otherwise-identical channel maps.
+
+Signed-off-by: Luca Barbato <lu_zero at gentoo.org>
+---
+ libavcodec/aacdec.c | 13 ++++++++++---
+ 1 file changed, 10 insertions(+), 3 deletions(-)
+
+--- a/libavcodec/aacdec.c
++++ b/libavcodec/aacdec.c
+@@ -457,12 +457,18 @@ static int output_configure(AACContext *
+     AVCodecContext *avctx = ac->avctx;
+     int i, channels = 0, ret;
+     uint64_t layout = 0;
++    uint8_t id_map[TYPE_END][MAX_ELEM_ID] = {{ 0 }};
++    uint8_t type_counts[TYPE_END] = { 0 };
+ 
+     if (ac->oc[1].layout_map != layout_map) {
+         memcpy(ac->oc[1].layout_map, layout_map, tags * sizeof(layout_map[0]));
+         ac->oc[1].layout_map_tags = tags;
+     }
+-
++    for (i = 0; i < tags; i++) {
++        int type =         layout_map[i][0];
++        int id =           layout_map[i][1];
++        id_map[type][id] = type_counts[type]++;
++    }
+     // Try to sniff a reasonable channel order, otherwise output the
+     // channels in the order the PCE declared them.
+     if (avctx->request_channel_layout != AV_CH_LAYOUT_NATIVE)
+@@ -470,12 +476,14 @@ static int output_configure(AACContext *
+     for (i = 0; i < tags; i++) {
+         int type =     layout_map[i][0];
+         int id =       layout_map[i][1];
++        int iid =      id_map[type][id];
+         int position = layout_map[i][2];
+         // Allocate or free elements depending on if they are in the
+         // current program configuration.
+-        ret = che_configure(ac, position, type, id, &channels);
++        ret = che_configure(ac, position, type, iid, &channels);
+         if (ret < 0)
+             return ret;
++        ac->tag_che_map[type][id] = ac->che[type][iid];
+     }
+     if (ac->oc[1].m4ac.ps == 1 && channels == 2) {
+         if (layout == AV_CH_FRONT_CENTER) {
+@@ -485,7 +493,6 @@ static int output_configure(AACContext *
+         }
+     }
+ 
+-    memcpy(ac->tag_che_map, ac->che, 4 * MAX_ELEM_ID * sizeof(ac->che[0][0]));
+     if (layout) avctx->channel_layout = layout;
+                             ac->oc[1].channel_layout = layout;
+     avctx->channels       = ac->oc[1].channels       = channels;
-- 
2.9.3