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new 2f209337fc avformat/mov: read DTS metadata from ddts box
2f209337fc is described below
commit 2f209337fc66b58bf0495265880bb37580c3f981
Author: Jun Zhao <[email protected]>
AuthorDate: Fri Jul 24 10:03:16 2026 +0800
Commit: Jun Zhao <[email protected]>
CommitDate: Fri Jul 24 10:36:46 2026 +0800
avformat/mov: read DTS metadata from ddts box
The MOV demuxer only handled the low four bits of ChannelLayout and
did not expose the DTS profile carried by StreamConstruction. It also
discarded the sample-entry channel count when ChannelLayout was zero.
Parse StreamConstruction, RepresentationType, and all 16 ChannelLayout
bits according to ETSI TS 102 114. Map StreamConstruction to the
corresponding FFmpeg DTS profile, and preserve the sample-entry channel
count for zero layouts unless RepresentationType explicitly signals two
encoded channels.
This also provides profile and channel metadata for encrypted samples
whose frame headers cannot be inspected.
Signed-off-by: Jun Zhao <[email protected]>
---
libavformat/mov.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 87 insertions(+), 11 deletions(-)
diff --git a/libavformat/mov.c b/libavformat/mov.c
index dc425e4e9f..bd5f456032 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -1166,6 +1166,73 @@ static int mov_read_dec3(MOVContext *c, AVIOContext *pb,
MOVAtom atom)
return 0;
}
+/* Maps the DTS `StreamConstruction` field (ETSI TS 102 114 Table E-2) to the
+ * coarse FFmpeg DTS profile enum. Extension-substream XLL maps to HD_MA;
+ * extension-substream XXCH, X96, or XBR maps to HD_HRA; core-substream XCH or
+ * XXCH maps to ES; core-substream X96 maps to 96/24; a core component alone
+ * maps to DTS; and extension-substream LBR maps to Express. Value 0
(undefined)
+ * and values outside 1..21 map to AV_PROFILE_UNKNOWN. */
+static int mov_dts_stream_construction_to_profile(unsigned int sc)
+{
+ static const int profile[22] = {
+ [ 1] = AV_PROFILE_DTS, /* core Core
*/
+ [ 2] = AV_PROFILE_DTS_ES, /* core Core + core XCH
*/
+ [ 3] = AV_PROFILE_DTS_ES, /* core Core + core XXCH
*/
+ [ 4] = AV_PROFILE_DTS_96_24, /* core Core + core X96
*/
+ [ 5] = AV_PROFILE_DTS_HD_HRA, /* core Core + ext XXCH
*/
+ [ 6] = AV_PROFILE_DTS_HD_HRA, /* core Core + ext XBR
*/
+ [ 7] = AV_PROFILE_DTS_HD_HRA, /* core Core + core XCH + ext XBR
*/
+ [ 8] = AV_PROFILE_DTS_HD_HRA, /* core Core + core XXCH + ext XBR
*/
+ [ 9] = AV_PROFILE_DTS_HD_HRA, /* core Core + ext XXCH + ext XBR
*/
+ [10] = AV_PROFILE_DTS_HD_HRA, /* core Core + ext X96
*/
+ [11] = AV_PROFILE_DTS_HD_HRA, /* core Core + core XCH + ext X96
*/
+ [12] = AV_PROFILE_DTS_HD_HRA, /* core Core + core XXCH + ext X96
*/
+ [13] = AV_PROFILE_DTS_HD_HRA, /* core Core + ext XXCH + ext X96
*/
+ [14] = AV_PROFILE_DTS_HD_MA, /* core Core + ext XLL
*/
+ [15] = AV_PROFILE_DTS_HD_MA, /* core Core + core XCH + ext XLL
*/
+ [16] = AV_PROFILE_DTS_HD_MA, /* core Core + core X96 + ext XLL
*/
+ [17] = AV_PROFILE_DTS_HD_MA, /* ext XLL
*/
+ [18] = AV_PROFILE_DTS_EXPRESS, /* ext LBR
*/
+ [19] = AV_PROFILE_DTS, /* ext Core
*/
+ [20] = AV_PROFILE_DTS_HD_HRA, /* ext Core + ext XXCH
*/
+ [21] = AV_PROFILE_DTS_HD_MA, /* ext Core + ext XLL
*/
+ };
+ if (!sc || sc > 21)
+ return AV_PROFILE_UNKNOWN;
+ return profile[sc];
+}
+
+/* Maps the 16-bit DTS `ChannelLayout` bitmask (ETSI TS 102 114 Table E-5) to
an
+ * ffmpeg channel mask. Pair bits follow Table 7-10 / DCA_SPEAKER_PAIR_*;
+ * LwRw (0x0400) and LssRss (0x0800) must not collapse onto SIDE like LsRs. */
+static uint64_t mov_dts_channel_layout_to_mask(unsigned int code)
+{
+ static const struct { unsigned int dts; uint64_t av; } map[] = {
+ { 0x0001, AV_CH_FRONT_CENTER },
+ { 0x0002, AV_CH_FRONT_LEFT | AV_CH_FRONT_RIGHT },
+ { 0x0004, AV_CH_SIDE_LEFT | AV_CH_SIDE_RIGHT },
+ { 0x0008, AV_CH_LOW_FREQUENCY },
+ { 0x0010, AV_CH_BACK_CENTER },
+ { 0x0020, AV_CH_TOP_FRONT_LEFT | AV_CH_TOP_FRONT_RIGHT },
+ { 0x0040, AV_CH_BACK_LEFT | AV_CH_BACK_RIGHT },
+ { 0x0080, AV_CH_TOP_FRONT_CENTER },
+ { 0x0100, AV_CH_TOP_CENTER },
+ { 0x0200, AV_CH_FRONT_LEFT_OF_CENTER | AV_CH_FRONT_RIGHT_OF_CENTER },
+ { 0x0400, AV_CH_WIDE_LEFT | AV_CH_WIDE_RIGHT },
+ { 0x0800, AV_CH_SIDE_SURROUND_LEFT | AV_CH_SIDE_SURROUND_RIGHT },
+ { 0x1000, AV_CH_LOW_FREQUENCY_2 },
+ { 0x2000, AV_CH_TOP_SIDE_LEFT | AV_CH_TOP_SIDE_RIGHT },
+ { 0x4000, AV_CH_TOP_BACK_CENTER },
+ { 0x8000, AV_CH_TOP_BACK_LEFT | AV_CH_TOP_BACK_RIGHT },
+ };
+ uint64_t mask = 0;
+ int i;
+ for (i = 0; i < FF_ARRAY_ELEMS(map); i++)
+ if (code & map[i].dts)
+ mask |= map[i].av;
+ return mask;
+}
+
static int mov_read_ddts(MOVContext *c, AVIOContext *pb, MOVAtom atom)
{
#define DDTS_SIZE 20
@@ -1173,6 +1240,9 @@ static int mov_read_ddts(MOVContext *c, AVIOContext *pb,
MOVAtom atom)
AVStream *st = NULL;
uint32_t frame_duration_code = 0;
uint32_t channel_layout_code = 0;
+ uint64_t channel_layout_mask;
+ unsigned int stream_construction;
+ unsigned int representation_type;
GetBitContext gb;
int ret;
@@ -1195,7 +1265,12 @@ static int mov_read_ddts(MOVContext *c, AVIOContext *pb,
MOVAtom atom)
st->codecpar->bit_rate = get_bits_long(&gb, 32);
st->codecpar->bits_per_coded_sample = get_bits(&gb, 8);
frame_duration_code = get_bits(&gb, 2);
- skip_bits(&gb, 30); /* various fields */
+ stream_construction = get_bits(&gb, 5); /* Table E-2 - profile source */
+ skip_bits(&gb, 1); /* CoreLFEPresent */
+ skip_bits(&gb, 6); /* CoreLayout */
+ skip_bits(&gb, 14); /* CoreSize */
+ skip_bits(&gb, 1); /* StereoDownmix */
+ representation_type = get_bits(&gb, 3);
channel_layout_code = get_bits(&gb, 16);
st->codecpar->frame_size =
@@ -1204,17 +1279,18 @@ static int mov_read_ddts(MOVContext *c, AVIOContext
*pb, MOVAtom atom)
(frame_duration_code == 2) ? 2048 :
(frame_duration_code == 3) ? 4096 : 0;
- if (channel_layout_code > 0xff) {
- av_log(c->fc, AV_LOG_WARNING, "Unsupported DTS audio channel
layout\n");
+ /* Publish StreamConstruction as codecpar->profile, including for encrypted
+ * tracks where frame headers cannot be inspected. */
+ st->codecpar->profile =
mov_dts_stream_construction_to_profile(stream_construction);
+
+ channel_layout_mask = mov_dts_channel_layout_to_mask(channel_layout_code);
+ if (channel_layout_mask) {
+ av_channel_layout_uninit(&st->codecpar->ch_layout);
+ av_channel_layout_from_mask(&st->codecpar->ch_layout,
channel_layout_mask);
+ } else if (representation_type == 2 || representation_type == 3) {
+ av_channel_layout_uninit(&st->codecpar->ch_layout);
+ st->codecpar->ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_STEREO;
}
- av_channel_layout_uninit(&st->codecpar->ch_layout);
- av_channel_layout_from_mask(&st->codecpar->ch_layout,
- ((channel_layout_code & 0x1) ? AV_CH_FRONT_CENTER : 0) |
- ((channel_layout_code & 0x2) ? AV_CH_FRONT_LEFT : 0) |
- ((channel_layout_code & 0x2) ? AV_CH_FRONT_RIGHT : 0) |
- ((channel_layout_code & 0x4) ? AV_CH_SIDE_LEFT : 0) |
- ((channel_layout_code & 0x4) ? AV_CH_SIDE_RIGHT : 0) |
- ((channel_layout_code & 0x8) ? AV_CH_LOW_FREQUENCY : 0));
return 0;
}
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