mov: add support for reading and writing the 'chan' tag

This implements reading the tag in the demuxer and adds support for writing it
in the muxer. Some example channel layout tables for muxing are included for
ac3, aac, and alac, but they are not utilized yet.

5 files changed, 636 insertions, 2 deletions

diff --git a/libavformat/Makefile b/libavformat/Makefile
index fccb5f342f..9d2e946b3c 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -132,9 +132,10 @@ OBJS-$(CONFIG_MLP_MUXER)                 += rawenc.o
 OBJS-$(CONFIG_MM_DEMUXER)                += mm.o
 OBJS-$(CONFIG_MMF_DEMUXER)               += mmf.o pcm.o
 OBJS-$(CONFIG_MMF_MUXER)                 += mmf.o riff.o
-OBJS-$(CONFIG_MOV_DEMUXER)               += mov.o riff.o isom.o
+OBJS-$(CONFIG_MOV_DEMUXER)               += mov.o riff.o isom.o mov_chan.o
 OBJS-$(CONFIG_MOV_MUXER)                 += movenc.o riff.o isom.o avc.o \
-                                            movenchint.o rtpenc_chain.o
+                                            movenchint.o rtpenc_chain.o \
+                                            mov_chan.o
 OBJS-$(CONFIG_MP2_MUXER)                 += mp3enc.o rawenc.o
 OBJS-$(CONFIG_MP3_DEMUXER)               += mp3dec.o
 OBJS-$(CONFIG_MP3_MUXER)                 += mp3enc.o rawenc.o id3v2enc.o
diff --git a/libavformat/mov.c b/libavformat/mov.c
index a0b0794592..eef53e6d66 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -37,6 +37,7 @@
 #include "isom.h"
 #include "libavcodec/get_bits.h"
 #include "id3v1.h"
+#include "mov_chan.h"
 
 #if CONFIG_ZLIB
 #include <zlib.h>
@@ -554,6 +555,51 @@ static int mov_read_dac3(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     return 0;
 }
 
+static int mov_read_chan(MOVContext *c, AVIOContext *pb, MOVAtom atom)
+{
+    AVStream *st;
+    uint8_t version;
+    uint32_t flags, layout_tag, bitmap, num_descr;
+
+    if (c->fc->nb_streams < 1)
+        return 0;
+    st = c->fc->streams[c->fc->nb_streams-1];
+
+    if (atom.size < 16)
+        return 0;
+
+    version = avio_r8(pb);
+    flags   = avio_rb24(pb);
+
+    layout_tag = avio_rb32(pb);
+    bitmap     = avio_rb32(pb);
+    num_descr  = avio_rb32(pb);
+
+    if (atom.size < 16ULL + num_descr * 20ULL)
+        return 0;
+
+    av_dlog(c->fc, "chan: size=%ld version=%u flags=%u layout=%u bitmap=%u num_descr=%u\n",
+            atom.size, version, flags, layout_tag, bitmap, num_descr);
+
+#if 0
+    /* TODO: use the channel descriptions if the layout tag is 0 */
+    int i;
+    for (i = 0; i < num_descr; i++) {
+        uint32_t label, cflags;
+        float coords[3];
+        label     = avio_rb32(pb);          // mChannelLabel
+        cflags    = avio_rb32(pb);          // mChannelFlags
+        AV_WN32(&coords[0], avio_rl32(pb)); // mCoordinates[0]
+        AV_WN32(&coords[1], avio_rl32(pb)); // mCoordinates[1]
+        AV_WN32(&coords[2], avio_rl32(pb)); // mCoordinates[2]
+    }
+#endif
+
+    st->codec->channel_layout = ff_mov_get_channel_layout(layout_tag, bitmap);
+
+    return 0;
+}
+
 static int mov_read_wfex(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 {
     AVStream *st;
@@ -2329,6 +2375,7 @@ static const MOVParseTableEntry mov_default_parse_table[] = {
 { MKTAG('w','i','d','e'), mov_read_wide }, /* place holder */
 { MKTAG('w','f','e','x'), mov_read_wfex },
 { MKTAG('c','m','o','v'), mov_read_cmov },
+{ MKTAG('c','h','a','n'), mov_read_chan }, /* channel layout */
 { 0, NULL }
 };
 
diff --git a/libavformat/mov_chan.c b/libavformat/mov_chan.c
new file mode 100644
index 0000000000..3c1ced6564
--- /dev/null
+++ b/libavformat/mov_chan.c
@@ -0,0 +1,505 @@
+/*
+ * Copyright (c) 2011 Justin Ruggles
+ *
+ * This file is part of Libav.
+ *
+ * Libav is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * Libav is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * mov 'chan' tag reading/writing.
+ * @author Justin Ruggles
+ */
+
+#include <stdint.h>
+
+#include "libavutil/audioconvert.h"
+#include "libavcodec/avcodec.h"
+#include "mov_chan.h"
+
+/**
+ * Channel Layout Tag
+ * This tells which channels are present in the audio stream and the order in
+ * which they appear.
+ *
+ * @note We're using the channel layout tag to indicate channel order
+ *       when the value is greater than 0x10000. The Apple documentation has
+ *       some contradictions as to how this is actually supposed to be handled.
+ *
+ *       Core Audio File Format Spec:
+ *           "The high 16 bits indicates a specific ordering of the channels."
+ *       Core Audio Data Types Reference:
+ *           "These identifiers specify the channels included in a layout but
+ *            do not specify a particular ordering of those channels."
+ */
+enum MovChannelLayoutTag {
+    MOV_CH_LAYOUT_UNKNOWN               = 0xFFFF0000,
+    MOV_CH_LAYOUT_USE_DESCRIPTIONS      = (  0 << 16) | 0,
+    MOV_CH_LAYOUT_USE_BITMAP            = (  1 << 16) | 0,
+    MOV_CH_LAYOUT_DISCRETEINORDER       = (147 << 16) | 0,
+    MOV_CH_LAYOUT_MONO                  = (100 << 16) | 1,
+    MOV_CH_LAYOUT_STEREO                = (101 << 16) | 2,
+    MOV_CH_LAYOUT_STEREOHEADPHONES      = (102 << 16) | 2,
+    MOV_CH_LAYOUT_MATRIXSTEREO          = (103 << 16) | 2,
+    MOV_CH_LAYOUT_MIDSIDE               = (104 << 16) | 2,
+    MOV_CH_LAYOUT_XY                    = (105 << 16) | 2,
+    MOV_CH_LAYOUT_BINAURAL              = (106 << 16) | 2,
+    MOV_CH_LAYOUT_AMBISONIC_B_FORMAT    = (107 << 16) | 4,
+    MOV_CH_LAYOUT_QUADRAPHONIC          = (108 << 16) | 4,
+    MOV_CH_LAYOUT_PENTAGONAL            = (109 << 16) | 5,
+    MOV_CH_LAYOUT_HEXAGONAL             = (110 << 16) | 6,
+    MOV_CH_LAYOUT_OCTAGONAL             = (111 << 16) | 8,
+    MOV_CH_LAYOUT_CUBE                  = (112 << 16) | 8,
+    MOV_CH_LAYOUT_MPEG_3_0_A            = (113 << 16) | 3,
+    MOV_CH_LAYOUT_MPEG_3_0_B            = (114 << 16) | 3,
+    MOV_CH_LAYOUT_MPEG_4_0_A            = (115 << 16) | 4,
+    MOV_CH_LAYOUT_MPEG_4_0_B            = (116 << 16) | 4,
+    MOV_CH_LAYOUT_MPEG_5_0_A            = (117 << 16) | 5,
+    MOV_CH_LAYOUT_MPEG_5_0_B            = (118 << 16) | 5,
+    MOV_CH_LAYOUT_MPEG_5_0_C            = (119 << 16) | 5,
+    MOV_CH_LAYOUT_MPEG_5_0_D            = (120 << 16) | 5,
+    MOV_CH_LAYOUT_MPEG_5_1_A            = (121 << 16) | 6,
+    MOV_CH_LAYOUT_MPEG_5_1_B            = (122 << 16) | 6,
+    MOV_CH_LAYOUT_MPEG_5_1_C            = (123 << 16) | 6,
+    MOV_CH_LAYOUT_MPEG_5_1_D            = (124 << 16) | 6,
+    MOV_CH_LAYOUT_MPEG_6_1_A            = (125 << 16) | 7,
+    MOV_CH_LAYOUT_MPEG_7_1_A            = (126 << 16) | 8,
+    MOV_CH_LAYOUT_MPEG_7_1_B            = (127 << 16) | 8,
+    MOV_CH_LAYOUT_MPEG_7_1_C            = (128 << 16) | 8,
+    MOV_CH_LAYOUT_EMAGIC_DEFAULT_7_1    = (129 << 16) | 8,
+    MOV_CH_LAYOUT_SMPTE_DTV             = (130 << 16) | 8,
+    MOV_CH_LAYOUT_ITU_2_1               = (131 << 16) | 3,
+    MOV_CH_LAYOUT_ITU_2_2               = (132 << 16) | 4,
+    MOV_CH_LAYOUT_DVD_4                 = (133 << 16) | 3,
+    MOV_CH_LAYOUT_DVD_5                 = (134 << 16) | 4,
+    MOV_CH_LAYOUT_DVD_6                 = (135 << 16) | 5,
+    MOV_CH_LAYOUT_DVD_10                = (136 << 16) | 4,
+    MOV_CH_LAYOUT_DVD_11                = (137 << 16) | 5,
+    MOV_CH_LAYOUT_DVD_18                = (138 << 16) | 5,
+    MOV_CH_LAYOUT_AUDIOUNIT_6_0         = (139 << 16) | 6,
+    MOV_CH_LAYOUT_AUDIOUNIT_7_0         = (140 << 16) | 7,
+    MOV_CH_LAYOUT_AUDIOUNIT_7_0_FRONT   = (148 << 16) | 7,
+    MOV_CH_LAYOUT_AAC_6_0               = (141 << 16) | 6,
+    MOV_CH_LAYOUT_AAC_6_1               = (142 << 16) | 7,
+    MOV_CH_LAYOUT_AAC_7_0               = (143 << 16) | 7,
+    MOV_CH_LAYOUT_AAC_OCTAGONAL         = (144 << 16) | 8,
+    MOV_CH_LAYOUT_TMH_10_2_STD          = (145 << 16) | 16,
+    MOV_CH_LAYOUT_TMH_10_2_FULL         = (146 << 16) | 21,
+    MOV_CH_LAYOUT_AC3_1_0_1             = (149 << 16) | 2,
+    MOV_CH_LAYOUT_AC3_3_0               = (150 << 16) | 3,
+    MOV_CH_LAYOUT_AC3_3_1               = (151 << 16) | 4,
+    MOV_CH_LAYOUT_AC3_3_0_1             = (152 << 16) | 4,
+    MOV_CH_LAYOUT_AC3_2_1_1             = (153 << 16) | 4,
+    MOV_CH_LAYOUT_AC3_3_1_1             = (154 << 16) | 5,
+    MOV_CH_LAYOUT_EAC3_6_0_A            = (155 << 16) | 6,
+    MOV_CH_LAYOUT_EAC3_7_0_A            = (156 << 16) | 7,
+    MOV_CH_LAYOUT_EAC3_6_1_A            = (157 << 16) | 7,
+    MOV_CH_LAYOUT_EAC3_6_1_B            = (158 << 16) | 7,
+    MOV_CH_LAYOUT_EAC3_6_1_C            = (159 << 16) | 7,
+    MOV_CH_LAYOUT_EAC3_7_1_A            = (160 << 16) | 8,
+    MOV_CH_LAYOUT_EAC3_7_1_B            = (161 << 16) | 8,
+    MOV_CH_LAYOUT_EAC3_7_1_C            = (162 << 16) | 8,
+    MOV_CH_LAYOUT_EAC3_7_1_D            = (163 << 16) | 8,
+    MOV_CH_LAYOUT_EAC3_7_1_E            = (164 << 16) | 8,
+    MOV_CH_LAYOUT_EAC3_7_1_F            = (165 << 16) | 8,
+    MOV_CH_LAYOUT_EAC3_7_1_G            = (166 << 16) | 8,
+    MOV_CH_LAYOUT_EAC3_7_1_H            = (167 << 16) | 8,
+    MOV_CH_LAYOUT_DTS_3_1               = (168 << 16) | 4,
+    MOV_CH_LAYOUT_DTS_4_1               = (169 << 16) | 5,
+    MOV_CH_LAYOUT_DTS_6_0_A             = (170 << 16) | 6,
+    MOV_CH_LAYOUT_DTS_6_0_B             = (171 << 16) | 6,
+    MOV_CH_LAYOUT_DTS_6_0_C             = (172 << 16) | 6,
+    MOV_CH_LAYOUT_DTS_6_1_A             = (173 << 16) | 7,
+    MOV_CH_LAYOUT_DTS_6_1_B             = (174 << 16) | 7,
+    MOV_CH_LAYOUT_DTS_6_1_C             = (175 << 16) | 7,
+    MOV_CH_LAYOUT_DTS_6_1_D             = (182 << 16) | 7,
+    MOV_CH_LAYOUT_DTS_7_0               = (176 << 16) | 7,
+    MOV_CH_LAYOUT_DTS_7_1               = (177 << 16) | 8,
+    MOV_CH_LAYOUT_DTS_8_0_A             = (178 << 16) | 8,
+    MOV_CH_LAYOUT_DTS_8_0_B             = (179 << 16) | 8,
+    MOV_CH_LAYOUT_DTS_8_1_A             = (180 << 16) | 9,
+    MOV_CH_LAYOUT_DTS_8_1_B             = (181 << 16) | 9,
+};
+
+struct MovChannelLayoutMap {
+    uint32_t tag;
+    uint64_t layout;
+};
+
+static const struct MovChannelLayoutMap mov_ch_layout_map_misc[] = {
+    { MOV_CH_LAYOUT_USE_DESCRIPTIONS,   0 },
+    { MOV_CH_LAYOUT_USE_BITMAP,         0 },
+    { MOV_CH_LAYOUT_DISCRETEINORDER,    0 },
+    { MOV_CH_LAYOUT_UNKNOWN,            0 },
+    { MOV_CH_LAYOUT_TMH_10_2_STD,       0 }, // L,   R,  C,    Vhc, Lsd, Rsd,
+                                             // Ls,  Rs, Vhl,  Vhr, Lw,  Rw,
+                                             // Csd, Cs, LFE1, LFE2
+    { MOV_CH_LAYOUT_TMH_10_2_FULL,      0 }, // L,   R,  C,    Vhc,  Lsd, Rsd,
+                                             // Ls,  Rs, Vhl,  Vhr,  Lw,  Rw,
+                                             // Csd, Cs, LFE1, LFE2, Lc,  Rc,
+                                             // HI,  VI, Haptic
+    { 0, 0 },
+};
+
+static const struct MovChannelLayoutMap mov_ch_layout_map_1ch[] = {
+    { MOV_CH_LAYOUT_MONO,               AV_CH_LAYOUT_MONO }, // C
+};
+
+static const struct MovChannelLayoutMap mov_ch_layout_map_2ch[] = {
+    { MOV_CH_LAYOUT_STEREO,             AV_CH_LAYOUT_STEREO         }, // L, R
+    { MOV_CH_LAYOUT_STEREOHEADPHONES,   AV_CH_LAYOUT_STEREO         }, // L, R
+    { MOV_CH_LAYOUT_BINAURAL,           AV_CH_LAYOUT_STEREO         }, // L, R
+    { MOV_CH_LAYOUT_MIDSIDE,            AV_CH_LAYOUT_STEREO         }, // C, sides
+    { MOV_CH_LAYOUT_XY,                 AV_CH_LAYOUT_STEREO         }, // X (left), Y (right)
+
+    { MOV_CH_LAYOUT_MATRIXSTEREO,       AV_CH_LAYOUT_STEREO_DOWNMIX }, // Lt, Rt
+
+    { MOV_CH_LAYOUT_AC3_1_0_1,          AV_CH_LAYOUT_MONO |            // C, LFE
+                                        AV_CH_LOW_FREQUENCY         },
+    { 0, 0 },
+};
+
+static const struct MovChannelLayoutMap mov_ch_layout_map_3ch[] = {
+    { MOV_CH_LAYOUT_MPEG_3_0_A,         AV_CH_LAYOUT_SURROUND }, // L, R, C
+    { MOV_CH_LAYOUT_MPEG_3_0_B,         AV_CH_LAYOUT_SURROUND }, // C, L, R
+    { MOV_CH_LAYOUT_AC3_3_0,            AV_CH_LAYOUT_SURROUND }, // L, C, R
+
+    { MOV_CH_LAYOUT_ITU_2_1,            AV_CH_LAYOUT_2_1      }, // L, R, Cs
+
+    { MOV_CH_LAYOUT_DVD_4,              AV_CH_LAYOUT_2POINT1  }, // L, R, LFE
+    { 0, 0 },
+};
+
+static const struct MovChannelLayoutMap mov_ch_layout_map_4ch[] = {
+    { MOV_CH_LAYOUT_AMBISONIC_B_FORMAT, 0 },                    // W, X, Y, Z
+
+    { MOV_CH_LAYOUT_QUADRAPHONIC,       AV_CH_LAYOUT_QUAD    }, // L, R, Rls, Rrs
+
+    { MOV_CH_LAYOUT_MPEG_4_0_A,         AV_CH_LAYOUT_4POINT0 }, // L, R, C, Cs
+    { MOV_CH_LAYOUT_MPEG_4_0_B,         AV_CH_LAYOUT_4POINT0 }, // C, L, R, Cs
+    { MOV_CH_LAYOUT_AC3_3_1,            AV_CH_LAYOUT_4POINT0 }, // L, C, R, Cs
+
+    { MOV_CH_LAYOUT_ITU_2_2,            AV_CH_LAYOUT_2_2     }, // L, R, Ls, Rs
+
+    { MOV_CH_LAYOUT_DVD_5,              AV_CH_LAYOUT_2_1 |      // L, R, LFE, Cs
+                                        AV_CH_LOW_FREQUENCY  },
+    { MOV_CH_LAYOUT_AC3_2_1_1,          AV_CH_LAYOUT_2_1 |      // L, R, Cs, LFE
+                                        AV_CH_LOW_FREQUENCY  },
+
+    { MOV_CH_LAYOUT_DVD_10,             AV_CH_LAYOUT_3POINT1 }, // L, R, C, LFE
+    { MOV_CH_LAYOUT_AC3_3_0_1,          AV_CH_LAYOUT_3POINT1 }, // L, C, R, LFE
+    { MOV_CH_LAYOUT_DTS_3_1,            AV_CH_LAYOUT_3POINT1 }, // C, L, R, LFE
+    { 0, 0 },
+};
+
+static const struct MovChannelLayoutMap mov_ch_layout_map_5ch[] = {
+    { MOV_CH_LAYOUT_PENTAGONAL,         AV_CH_LAYOUT_5POINT0_BACK }, // L, R, Rls, Rrs, C
+
+    { MOV_CH_LAYOUT_MPEG_5_0_A,         AV_CH_LAYOUT_5POINT0 },      // L, R, C,  Ls, Rs
+    { MOV_CH_LAYOUT_MPEG_5_0_B,         AV_CH_LAYOUT_5POINT0 },      // L, R, Ls, Rs, C
+    { MOV_CH_LAYOUT_MPEG_5_0_C,         AV_CH_LAYOUT_5POINT0 },      // L, C, R,  Ls, Rs
+    { MOV_CH_LAYOUT_MPEG_5_0_D,         AV_CH_LAYOUT_5POINT0 },      // C, L, R,  Ls, Rs
+
+    { MOV_CH_LAYOUT_DVD_6,              AV_CH_LAYOUT_2_2 |           // L, R, LFE, Ls, Rs
+                                        AV_CH_LOW_FREQUENCY },
+    { MOV_CH_LAYOUT_DVD_18,             AV_CH_LAYOUT_2_2 |           // L, R, Ls, Rs, LFE
+                                        AV_CH_LOW_FREQUENCY },
+
+    { MOV_CH_LAYOUT_DVD_11,             AV_CH_LAYOUT_4POINT1 },      // L, R, C, LFE, Cs
+    { MOV_CH_LAYOUT_AC3_3_1_1,          AV_CH_LAYOUT_4POINT1 },      // L, C, R, Cs,  LFE
+    { MOV_CH_LAYOUT_DTS_4_1,            AV_CH_LAYOUT_4POINT1 },      // C, L, R, Cs,  LFE
+    { 0, 0 },
+};
+
+static const struct MovChannelLayoutMap mov_ch_layout_map_6ch[] = {
+    { MOV_CH_LAYOUT_HEXAGONAL,          AV_CH_LAYOUT_HEXAGONAL },      // L, R,  Rls, Rrs, C,   Cs
+    { MOV_CH_LAYOUT_DTS_6_0_C,          AV_CH_LAYOUT_HEXAGONAL },      // C, Cs, L,   R,   Rls, Rrs
+
+    { MOV_CH_LAYOUT_MPEG_5_1_A,         AV_CH_LAYOUT_5POINT1 },        // L, R, C,  LFE, Ls, Rs
+    { MOV_CH_LAYOUT_MPEG_5_1_B,         AV_CH_LAYOUT_5POINT1 },        // L, R, Ls, Rs,  C,  LFE
+    { MOV_CH_LAYOUT_MPEG_5_1_C,         AV_CH_LAYOUT_5POINT1 },        // L, C, R,  Ls,  Rs, LFE
+    { MOV_CH_LAYOUT_MPEG_5_1_D,         AV_CH_LAYOUT_5POINT1 },        // C, L, R,  Ls,  Rs, LFE
+
+    { MOV_CH_LAYOUT_AUDIOUNIT_6_0,      AV_CH_LAYOUT_6POINT0 },        // L, R, Ls, Rs, C,  Cs
+    { MOV_CH_LAYOUT_AAC_6_0,            AV_CH_LAYOUT_6POINT0 },        // C, L, R,  Ls, Rs, Cs
+    { MOV_CH_LAYOUT_EAC3_6_0_A,         AV_CH_LAYOUT_6POINT0 },        // L, C, R,  Ls, Rs, Cs
+
+    { MOV_CH_LAYOUT_DTS_6_0_A,          AV_CH_LAYOUT_6POINT0_FRONT },  // Lc, Rc, L, R, Ls, Rs
+
+    { MOV_CH_LAYOUT_DTS_6_0_B,          AV_CH_LAYOUT_5POINT0_BACK |    // C, L, R, Rls, Rrs, Ts
+                                        AV_CH_TOP_CENTER },
+    { 0, 0 },
+};
+
+static const struct MovChannelLayoutMap mov_ch_layout_map_7ch[] = {
+    { MOV_CH_LAYOUT_MPEG_6_1_A,          AV_CH_LAYOUT_6POINT1 },        // L, R, C, LFE, Ls, Rs,  Cs
+    { MOV_CH_LAYOUT_AAC_6_1,             AV_CH_LAYOUT_6POINT1 },        // C, L, R, Ls,  Rs, Cs,  LFE
+    { MOV_CH_LAYOUT_EAC3_6_1_A,          AV_CH_LAYOUT_6POINT1 },        // L, C, R, Ls,  Rs, LFE, Cs
+    { MOV_CH_LAYOUT_DTS_6_1_D,           AV_CH_LAYOUT_6POINT1 },        // C, L, R, Ls,  Rs, LFE, Cs
+
+    { MOV_CH_LAYOUT_AUDIOUNIT_7_0,       AV_CH_LAYOUT_7POINT0 },        // L, R, Ls, Rs, C,  Rls, Rrs
+    { MOV_CH_LAYOUT_AAC_7_0,             AV_CH_LAYOUT_7POINT0 },        // C, L, R,  Ls, Rs, Rls, Rrs
+    { MOV_CH_LAYOUT_EAC3_7_0_A,          AV_CH_LAYOUT_7POINT0 },        // L, C, R,  Ls, Rs, Rls, Rrs
+
+    { MOV_CH_LAYOUT_AUDIOUNIT_7_0_FRONT, AV_CH_LAYOUT_7POINT0_FRONT },  // L,  R, Ls, Rs, C, Lc, Rc
+    { MOV_CH_LAYOUT_DTS_7_0,             AV_CH_LAYOUT_7POINT0_FRONT },  // Lc, C, Rc, L,  R, Ls, Rs
+
+    { MOV_CH_LAYOUT_EAC3_6_1_B,          AV_CH_LAYOUT_5POINT1 |         // L, C, R, Ls, Rs, LFE, Ts
+                                         AV_CH_TOP_CENTER },
+
+    { MOV_CH_LAYOUT_EAC3_6_1_C,          AV_CH_LAYOUT_5POINT1 |         // L, C, R, Ls, Rs, LFE, Vhc
+                                         AV_CH_TOP_FRONT_CENTER },
+
+    { MOV_CH_LAYOUT_DTS_6_1_A,           AV_CH_LAYOUT_6POINT1_FRONT },  // Lc, Rc, L, R, Ls, Rs, LFE
+
+    { MOV_CH_LAYOUT_DTS_6_1_B,           AV_CH_LAYOUT_5POINT1_BACK |    // C, L, R, Rls, Rrs, Ts, LFE
+                                         AV_CH_TOP_CENTER },
+
+    { MOV_CH_LAYOUT_DTS_6_1_C,           AV_CH_LAYOUT_6POINT1_BACK },   // C, Cs, L, R, Rls, Rrs, LFE
+    { 0, 0 },
+};
+
+static const struct MovChannelLayoutMap mov_ch_layout_map_8ch[] = {
+    { MOV_CH_LAYOUT_OCTAGONAL,           AV_CH_LAYOUT_OCTAGONAL },      // L, R, Rls, Rrs, C,  Cs,  Ls,  Rs
+    { MOV_CH_LAYOUT_AAC_OCTAGONAL,       AV_CH_LAYOUT_OCTAGONAL },      // C, L, R,   Ls,  Rs, Rls, Rrs, Cs
+
+    { MOV_CH_LAYOUT_CUBE,                AV_CH_LAYOUT_QUAD     |        // L, R, Rls, Rrs, Vhl, Vhr, Rlt, Rrt
+                                         AV_CH_TOP_FRONT_LEFT  |
+                                         AV_CH_TOP_FRONT_RIGHT |
+                                         AV_CH_TOP_BACK_LEFT   |
+                                         AV_CH_TOP_BACK_RIGHT },
+
+    { MOV_CH_LAYOUT_MPEG_7_1_A,          AV_CH_LAYOUT_7POINT1_WIDE },   // L,  R,  C,  LFE, Ls, Rs,  Lc, Rc
+    { MOV_CH_LAYOUT_MPEG_7_1_B,          AV_CH_LAYOUT_7POINT1_WIDE },   // C,  Lc, Rc, L,   R,  Ls,  Rs, LFE
+    { MOV_CH_LAYOUT_EMAGIC_DEFAULT_7_1,  AV_CH_LAYOUT_7POINT1_WIDE },   // L,  R,  Ls, Rs,  C,  LFE, Lc, Rc
+    { MOV_CH_LAYOUT_EAC3_7_1_B,          AV_CH_LAYOUT_7POINT1_WIDE },   // L,  C,  R,  Ls,  Rs, LFE, Lc, Rc
+    { MOV_CH_LAYOUT_DTS_7_1,             AV_CH_LAYOUT_7POINT1_WIDE },   // Lc, C,  Rc, L,   R,  Ls,  Rs, LFE
+
+    { MOV_CH_LAYOUT_MPEG_7_1_C,          AV_CH_LAYOUT_7POINT1 },        // L, R, C, LFE, Ls, Rs,  Rls, Rrs
+    { MOV_CH_LAYOUT_EAC3_7_1_A,          AV_CH_LAYOUT_7POINT1 },        // L, C, R, Ls,  Rs, LFE, Rls, Rrs
+
+    { MOV_CH_LAYOUT_SMPTE_DTV,           AV_CH_LAYOUT_5POINT1 |         // L, R, C, LFE, Ls, Rs, Lt, Rt
+                                         AV_CH_LAYOUT_STEREO_DOWNMIX },
+
+    { MOV_CH_LAYOUT_EAC3_7_1_C,          AV_CH_LAYOUT_5POINT1        |  // L, C, R, Ls, Rs, LFE, Lsd, Rsd
+                                         AV_CH_SURROUND_DIRECT_LEFT  |
+                                         AV_CH_SURROUND_DIRECT_RIGHT },
+
+    { MOV_CH_LAYOUT_EAC3_7_1_D,          AV_CH_LAYOUT_5POINT1 |         // L, C, R, Ls, Rs, LFE, Lw, Rw
+                                         AV_CH_WIDE_LEFT      |
+                                         AV_CH_WIDE_RIGHT },
+
+    { MOV_CH_LAYOUT_EAC3_7_1_E,          AV_CH_LAYOUT_5POINT1 |         // L, C, R, Ls, Rs, LFE, Vhl, Vhr
+                                         AV_CH_TOP_FRONT_LEFT |
+                                         AV_CH_TOP_FRONT_RIGHT },
+
+    { MOV_CH_LAYOUT_EAC3_7_1_F,          AV_CH_LAYOUT_5POINT1 |         // L, C, R, Ls, Rs, LFE, Cs, Ts
+                                         AV_CH_BACK_CENTER    |
+                                         AV_CH_TOP_CENTER },
+
+    { MOV_CH_LAYOUT_EAC3_7_1_G,          AV_CH_LAYOUT_5POINT1 |         // L, C, R, Ls, Rs, LFE, Cs, Vhc
+                                         AV_CH_BACK_CENTER    |
+                                         AV_CH_TOP_FRONT_CENTER },
+
+    { MOV_CH_LAYOUT_EAC3_7_1_H,          AV_CH_LAYOUT_5POINT1 |         // L, C, R, Ls, Rs, LFE, Ts, Vhc
+                                         AV_CH_TOP_CENTER     |
+                                         AV_CH_TOP_FRONT_CENTER },
+
+    { MOV_CH_LAYOUT_DTS_8_0_A,           AV_CH_LAYOUT_2_2           |   // Lc, Rc, L, R, Ls, Rs, Rls, Rrs
+                                         AV_CH_BACK_LEFT            |
+                                         AV_CH_BACK_RIGHT           |
+                                         AV_CH_FRONT_LEFT_OF_CENTER |
+                                         AV_CH_FRONT_RIGHT_OF_CENTER },
+
+    { MOV_CH_LAYOUT_DTS_8_0_B,           AV_CH_LAYOUT_5POINT0        |  // Lc, C, Rc, L, R, Ls, Cs, Rs
+                                         AV_CH_FRONT_LEFT_OF_CENTER  |
+                                         AV_CH_FRONT_RIGHT_OF_CENTER |
+                                         AV_CH_BACK_CENTER },
+    { 0, 0 },
+};
+
+static const struct MovChannelLayoutMap mov_ch_layout_map_9ch[] = {
+    { MOV_CH_LAYOUT_DTS_8_1_A,           AV_CH_LAYOUT_2_2            | // Lc, Rc, L, R, Ls, Rs, Rls, Rrs, LFE
+                                         AV_CH_BACK_LEFT             |
+                                         AV_CH_BACK_RIGHT            |
+                                         AV_CH_FRONT_LEFT_OF_CENTER  |
+                                         AV_CH_FRONT_RIGHT_OF_CENTER |
+                                         AV_CH_LOW_FREQUENCY },
+
+    { MOV_CH_LAYOUT_DTS_8_1_B,           AV_CH_LAYOUT_7POINT1_WIDE   | // Lc, C, Rc, L, R, Ls, Cs, Rs, LFE
+                                         AV_CH_BACK_CENTER },
+    { 0, 0 },
+};
+
+static const struct MovChannelLayoutMap *mov_ch_layout_map[] = {
+    mov_ch_layout_map_misc,
+    mov_ch_layout_map_1ch,
+    mov_ch_layout_map_2ch,
+    mov_ch_layout_map_3ch,
+    mov_ch_layout_map_4ch,
+    mov_ch_layout_map_5ch,
+    mov_ch_layout_map_6ch,
+    mov_ch_layout_map_7ch,
+    mov_ch_layout_map_8ch,
+    mov_ch_layout_map_9ch,
+};
+
+static const enum MovChannelLayoutTag mov_ch_layouts_aac[] = {
+    MOV_CH_LAYOUT_MONO,
+    MOV_CH_LAYOUT_STEREO,
+    MOV_CH_LAYOUT_AC3_1_0_1,
+    MOV_CH_LAYOUT_MPEG_3_0_B,
+    MOV_CH_LAYOUT_ITU_2_1,
+    MOV_CH_LAYOUT_DVD_4,
+    MOV_CH_LAYOUT_QUADRAPHONIC,
+    MOV_CH_LAYOUT_MPEG_4_0_B,
+    MOV_CH_LAYOUT_ITU_2_2,
+    MOV_CH_LAYOUT_AC3_2_1_1,
+    MOV_CH_LAYOUT_DTS_3_1,
+    MOV_CH_LAYOUT_MPEG_5_0_D,
+    MOV_CH_LAYOUT_DVD_18,
+    MOV_CH_LAYOUT_DTS_4_1,
+    MOV_CH_LAYOUT_MPEG_5_1_D,
+    MOV_CH_LAYOUT_AAC_6_0,
+    MOV_CH_LAYOUT_DTS_6_0_A,
+    MOV_CH_LAYOUT_AAC_6_1,
+    MOV_CH_LAYOUT_AAC_7_0,
+    MOV_CH_LAYOUT_DTS_6_1_A,
+    MOV_CH_LAYOUT_AAC_OCTAGONAL,
+    MOV_CH_LAYOUT_MPEG_7_1_B,
+    MOV_CH_LAYOUT_DTS_8_0_A,
+    0,
+};
+
+static const enum MovChannelLayoutTag mov_ch_layouts_ac3[] = {
+    MOV_CH_LAYOUT_MONO,
+    MOV_CH_LAYOUT_STEREO,
+    MOV_CH_LAYOUT_AC3_1_0_1,
+    MOV_CH_LAYOUT_AC3_3_0,
+    MOV_CH_LAYOUT_ITU_2_1,
+    MOV_CH_LAYOUT_DVD_4,
+    MOV_CH_LAYOUT_AC3_3_1,
+    MOV_CH_LAYOUT_ITU_2_2,
+    MOV_CH_LAYOUT_AC3_2_1_1,
+    MOV_CH_LAYOUT_AC3_3_0_1,
+    MOV_CH_LAYOUT_MPEG_5_0_C,
+    MOV_CH_LAYOUT_DVD_18,
+    MOV_CH_LAYOUT_AC3_3_1_1,
+    MOV_CH_LAYOUT_MPEG_5_1_C,
+    0,
+};
+
+static const enum MovChannelLayoutTag mov_ch_layouts_alac[] = {
+    MOV_CH_LAYOUT_MONO,
+    MOV_CH_LAYOUT_STEREO,
+    MOV_CH_LAYOUT_MPEG_3_0_B,
+    MOV_CH_LAYOUT_MPEG_4_0_B,
+    MOV_CH_LAYOUT_MPEG_5_0_D,
+    MOV_CH_LAYOUT_MPEG_5_1_D,
+    MOV_CH_LAYOUT_AAC_6_1,
+    MOV_CH_LAYOUT_MPEG_7_1_B,
+    0,
+};
+
+static const struct {
+    enum CodecID codec_id;
+    const enum MovChannelLayoutTag *layouts;
+} mov_codec_ch_layouts[] = {
+    { CODEC_ID_AAC,     mov_ch_layouts_aac      },
+    { CODEC_ID_AC3,     mov_ch_layouts_ac3      },
+    { CODEC_ID_ALAC,    mov_ch_layouts_alac     },
+    { CODEC_ID_NONE,    NULL                    },
+};
+
+uint64_t ff_mov_get_channel_layout(uint32_t tag, uint32_t bitmap)
+{
+    int i, channels;
+    const struct MovChannelLayoutMap *layout_map;
+
+    /* handle the use of the channel descriptions */
+    /* TODO: map MOV channel labels to Libav channels */
+    if (tag == MOV_CH_LAYOUT_USE_DESCRIPTIONS)
+        return 0;
+
+    /* handle the use of the channel bitmap */
+    if (tag == MOV_CH_LAYOUT_USE_BITMAP)
+        return bitmap < 0x40000 ? bitmap : 0;
+
+    /* get the layout map based on the channel count for the specified layout tag */
+    channels = tag & 0xFFFF;
+    if (channels > 9)
+        channels = 0;
+    layout_map = mov_ch_layout_map[channels];
+
+    /* find the channel layout for the specified layout tag */
+    for (i = 0; layout_map[i].tag != 0; i++) {
+        if (layout_map[i].tag == tag)
+            break;
+    }
+    return layout_map[i].layout;
+}
+
+uint32_t ff_mov_get_channel_layout_tag(enum CodecID codec_id,
+                                       uint64_t channel_layout,
+                                       uint32_t *bitmap)
+{
+    int i, j;
+    uint32_t tag = 0;
+    const enum MovChannelLayoutTag *layouts = NULL;
+
+    /* find the layout list for the specified codec */
+    for (i = 0; mov_codec_ch_layouts[i].codec_id != CODEC_ID_NONE; i++) {
+        if (mov_codec_ch_layouts[i].codec_id == codec_id)
+            break;
+    }
+    if (mov_codec_ch_layouts[i].codec_id != CODEC_ID_NONE)
+        layouts = mov_codec_ch_layouts[i].layouts;
+
+    if (layouts) {
+        int channels;
+        const struct MovChannelLayoutMap *layout_map;
+
+        /* get the layout map based on the channel count */
+        channels = av_get_channel_layout_nb_channels(channel_layout);
+        if (channels > 9)
+            channels = 0;
+        layout_map = mov_ch_layout_map[channels];
+
+        /* find the layout tag for the specified channel layout */
+        for (i = 0; layouts[i] != 0; i++) {
+            if (layouts[i] & 0xFFFF != channels)
+                continue;
+            for (j = 0; layout_map[j].tag != 0; j++) {
+                if (layout_map[j].tag    == layouts[i] &&
+                    layout_map[j].layout == channel_layout)
+                    break;
+            }
+            if (layout_map[j].tag)
+                break;
+        }
+        tag = layouts[i];
+    }
+
+    /* if no tag was found, use channel bitmap as a backup if possible */
+    if (tag == 0 && channel_layout > 0 && channel_layout < 0x40000) {
+        tag     = MOV_CH_LAYOUT_USE_BITMAP;
+        *bitmap = (uint32_t)channel_layout;
+    } else
+        *bitmap = 0;
+
+    /* TODO: set channel descriptions as a secondary backup */
+
+    return tag;
+}
diff --git a/libavformat/mov_chan.h b/libavformat/mov_chan.h
new file mode 100644
index 0000000000..9723340102
--- /dev/null
+++ b/libavformat/mov_chan.h
@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2011 Justin Ruggles
+ *
+ * This file is part of Libav.
+ *
+ * Libav is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * Libav is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * mov 'chan' tag reading/writing.
+ * @author Justin Ruggles
+ */
+
+#ifndef AVFORMAT_MOV_CHAN_H
+#define AVFORMAT_MOV_CHAN_H
+
+#include <stdint.h>
+
+#include "libavcodec/avcodec.h"
+
+/**
+ * Get the channel layout for the specified channel layout tag.
+ *
+ * @param[in]  tag     channel layout tag
+ * @param[out] bitmap  channel bitmap (only used if needed)
+ * @return             channel layout
+ */
+uint64_t ff_mov_get_channel_layout(uint32_t tag, uint32_t bitmap);
+
+/**
+ * Get the channel layout tag for the specified codec id and channel layout.
+ * If the layout tag was not found, use a channel bitmap if possible.
+ *
+ * @param[in]  codec_id        codec id
+ * @param[in]  channel_layout  channel layout
+ * @param[out] bitmap          channel bitmap
+ * @return                     channel layout tag
+ */
+uint32_t ff_mov_get_channel_layout_tag(enum CodecID codec_id,
+                                       uint64_t channel_layout,
+                                       uint32_t *bitmap);
+
+#endif /* AVFORMAT_MOV_CHAN_H */
diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index 5d770aa90e..897a204e1d 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -37,6 +37,7 @@
 #include "libavutil/opt.h"
 #include "libavutil/dict.h"
 #include "rtpenc.h"
+#include "mov_chan.h"
 
 #undef NDEBUG
 #include <assert.h>
@@ -338,6 +339,31 @@ static int mov_write_ms_tag(AVIOContext *pb, MOVTrack *track)
     return updateSize(pb, pos);
 }
 
+static int mov_write_chan_tag(AVIOContext *pb, MOVTrack *track)
+{
+    uint32_t layout_tag, bitmap;
+    int64_t pos = avio_tell(pb);
+
+    layout_tag = ff_mov_get_channel_layout_tag(track->enc->codec_id,
+                                               track->enc->channel_layout,
+                                               &bitmap);
+    if (!layout_tag) {
+        av_log(track->enc, AV_LOG_WARNING, "not writing 'chan' tag due to "
+               "lack of channel information\n");
+        return 0;
+    }
+
+    avio_wb32(pb, 0);           // Size
+    ffio_wfourcc(pb, "chan");   // Type
+    avio_w8(pb, 0);             // Version
+    avio_wb24(pb, 0);           // Flags
+    avio_wb32(pb, layout_tag);  // mChannelLayoutTag
+    avio_wb32(pb, bitmap);      // mChannelBitmap
+    avio_wb32(pb, 0);           // mNumberChannelDescriptions
+
+    return updateSize(pb, pos);
+}
+
 static int mov_write_wave_tag(AVIOContext *pb, MOVTrack *track)
 {
     int64_t pos = avio_tell(pb);