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channel_layout: add support for Ambisonic

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Signed-off-by: James Almer <jamrial@gmail.com>
release/5.1
Vittorio Giovara 8 years ago committed by James Almer
parent 2f8ccca2fa
commit 886847afa0
4 changed files with 294 additions and 5 deletions
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  1. 182
      libavutil/channel_layout.c
  2. 52
      libavutil/channel_layout.h
  3. 40
      libavutil/tests/channel_layout.c
  4. 25
      tests/ref/fate/channel_layout

182
libavutil/channel_layout.c
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@ -34,6 +34,9 @@
#include "macros.h"
#include "opt.h"
#define CHAN_IS_AMBI(x) ((x) >= AV_CHAN_AMBISONIC_BASE &&\
(x) <= AV_CHAN_AMBISONIC_END)
struct channel_name {
const char *name;
const char *description;
@ -82,7 +85,10 @@ static const char *get_channel_name(enum AVChannel channel_id)
void av_channel_name_bprint(AVBPrint *bp, enum AVChannel channel_id)
{
if ((unsigned)channel_id < FF_ARRAY_ELEMS(channel_names))
if (channel_id >= AV_CHAN_AMBISONIC_BASE &&
channel_id <= AV_CHAN_AMBISONIC_END)
av_bprintf(bp, "AMBI%d", channel_id - AV_CHAN_AMBISONIC_BASE);
else if ((unsigned)channel_id < FF_ARRAY_ELEMS(channel_names))
av_bprintf(bp, "%s", channel_names[channel_id].name);
else if (channel_id == AV_CHAN_NONE)
av_bprintf(bp, "NONE");
@ -105,7 +111,10 @@ int av_channel_name(char *buf, size_t buf_size, enum AVChannel channel_id)
void av_channel_description_bprint(AVBPrint *bp, enum AVChannel channel_id)
{
if ((unsigned)channel_id < FF_ARRAY_ELEMS(channel_names))
if (channel_id >= AV_CHAN_AMBISONIC_BASE &&
channel_id <= AV_CHAN_AMBISONIC_END)
av_bprintf(bp, "ambisonic ACN %d", channel_id - AV_CHAN_AMBISONIC_BASE);
else if ((unsigned)channel_id < FF_ARRAY_ELEMS(channel_names))
av_bprintf(bp, "%s", channel_names[channel_id].description);
else
av_bprintf(bp, "user %d", channel_id);
@ -129,6 +138,14 @@ enum AVChannel av_channel_from_string(const char *str)
int i;
char *endptr = (char *)str;
enum AVChannel id = AV_CHAN_NONE;
if (!strncmp(str, "AMBI", 4)) {
i = strtol(str + 4, NULL, 0);
if (i < 0 || i > AV_CHAN_AMBISONIC_END - AV_CHAN_AMBISONIC_BASE)
return AV_CHAN_NONE;
return AV_CHAN_AMBISONIC_BASE + i;
}
for (i = 0; i < FF_ARRAY_ELEMS(channel_names); i++) {
if (channel_names[i].name && !strcmp(str, channel_names[i].name))
return i;
@ -396,6 +413,65 @@ int av_channel_layout_from_string(AVChannelLayout *channel_layout,
}
}
/* ambisonic */
if (!strncmp(str, "ambisonic ", 10)) {
const char *p = str + 10;
char *endptr;
AVChannelLayout extra = {0};
int order;
order = strtol(p, &endptr, 0);
if (order < 0 || order + 1 > INT_MAX / (order + 1) ||
(*endptr && *endptr != '+'))
return AVERROR(EINVAL);
channel_layout->order = AV_CHANNEL_ORDER_AMBISONIC;
channel_layout->nb_channels = (order + 1) * (order + 1);
if (*endptr) {
int ret = av_channel_layout_from_string(&extra, endptr + 1);
if (ret < 0)
return ret;
if (extra.nb_channels >= INT_MAX - channel_layout->nb_channels) {
av_channel_layout_uninit(&extra);
return AVERROR(EINVAL);
}
if (extra.order == AV_CHANNEL_ORDER_NATIVE) {
channel_layout->u.mask = extra.u.mask;
} else {
channel_layout->order = AV_CHANNEL_ORDER_CUSTOM;
channel_layout->u.map =
av_calloc(channel_layout->nb_channels + extra.nb_channels,
sizeof(*channel_layout->u.map));
if (!channel_layout->u.map) {
av_channel_layout_uninit(&extra);
return AVERROR(ENOMEM);
}
for (i = 0; i < channel_layout->nb_channels; i++)
channel_layout->u.map[i].id = AV_CHAN_AMBISONIC_BASE + i;
for (i = 0; i < extra.nb_channels; i++) {
enum AVChannel ch = av_channel_layout_channel_from_index(&extra, i);
if (CHAN_IS_AMBI(ch)) {
av_channel_layout_uninit(&extra);
return AVERROR(EINVAL);
}
channel_layout->u.map[channel_layout->nb_channels + i].id = ch;
if (extra.order == AV_CHANNEL_ORDER_CUSTOM &&
extra.u.map[i].name[0])
av_strlcpy(channel_layout->u.map[channel_layout->nb_channels + i].name,
extra.u.map[i].name,
sizeof(channel_layout->u.map[channel_layout->nb_channels + i].name));
}
}
channel_layout->nb_channels += extra.nb_channels;
av_channel_layout_uninit(&extra);
}
return 0;
}
chlist = av_strdup(str);
if (!chlist)
return AVERROR(ENOMEM);
@ -566,6 +642,77 @@ int av_channel_layout_copy(AVChannelLayout *dst, const AVChannelLayout *src)
return 0;
}
/**
* If the custom layout is n-th order standard-order ambisonic, with optional
* extra non-diegetic channels at the end, write its string description in bp.
* Return a negative error code on error.
*/
static int try_describe_ambisonic(AVBPrint *bp, const AVChannelLayout *channel_layout)
{
int i, highest_ambi, order;
highest_ambi = -1;
if (channel_layout->order == AV_CHANNEL_ORDER_AMBISONIC)
highest_ambi = channel_layout->nb_channels - av_popcount64(channel_layout->u.mask) - 1;
else {
const AVChannelCustom *map = channel_layout->u.map;
for (i = 0; i < channel_layout->nb_channels; i++) {
int is_ambi = CHAN_IS_AMBI(map[i].id);
/* ambisonic following non-ambisonic */
if (i > 0 && is_ambi && !CHAN_IS_AMBI(map[i - 1].id))
return 0;
/* non-default ordering */
if (is_ambi && map[i].id - AV_CHAN_AMBISONIC_BASE != i)
return 0;
if (CHAN_IS_AMBI(map[i].id))
highest_ambi = i;
}
}
/* no ambisonic channels*/
if (highest_ambi < 0)
return 0;
order = floor(sqrt(highest_ambi));
/* incomplete order - some harmonics are missing */
if ((order + 1) * (order + 1) != highest_ambi + 1)
return 0;
av_bprintf(bp, "ambisonic %d", order);
/* extra channels present */
if (highest_ambi < channel_layout->nb_channels - 1) {
AVChannelLayout extra = { 0 };
char buf[128];
if (channel_layout->order == AV_CHANNEL_ORDER_AMBISONIC) {
extra.order = AV_CHANNEL_ORDER_NATIVE;
extra.nb_channels = av_popcount64(channel_layout->u.mask);
extra.u.mask = channel_layout->u.mask;
} else {
const AVChannelCustom *map = channel_layout->u.map;
extra.order = AV_CHANNEL_ORDER_CUSTOM;
extra.nb_channels = channel_layout->nb_channels - highest_ambi - 1;
extra.u.map = av_calloc(extra.nb_channels, sizeof(*extra.u.map));
if (!extra.u.map)
return AVERROR(ENOMEM);
memcpy(extra.u.map, &map[highest_ambi + 1],
sizeof(*extra.u.map) * extra.nb_channels);
}
av_channel_layout_describe(&extra, buf, sizeof(buf));
av_channel_layout_uninit(&extra);
av_bprintf(bp, "+%s", buf);
}
return 0;
}
int av_channel_layout_describe_bprint(const AVChannelLayout *channel_layout,
AVBPrint *bp)
{
@ -580,6 +727,11 @@ int av_channel_layout_describe_bprint(const AVChannelLayout *channel_layout,
}
// fall-through
case AV_CHANNEL_ORDER_CUSTOM:
if (channel_layout->order == AV_CHANNEL_ORDER_CUSTOM) {
int res = try_describe_ambisonic(bp, channel_layout);
if (res < 0 || bp->len)
return res;
}
if (channel_layout->nb_channels)
av_bprintf(bp, "%d channels (", channel_layout->nb_channels);
for (i = 0; i < channel_layout->nb_channels; i++) {
@ -604,6 +756,8 @@ int av_channel_layout_describe_bprint(const AVChannelLayout *channel_layout,
case AV_CHANNEL_ORDER_UNSPEC:
av_bprintf(bp, "%d channels", channel_layout->nb_channels);
return 0;
case AV_CHANNEL_ORDER_AMBISONIC:
return try_describe_ambisonic(bp, channel_layout);
default:
return AVERROR(EINVAL);
}
@ -638,6 +792,13 @@ av_channel_layout_channel_from_index(const AVChannelLayout *channel_layout,
switch (channel_layout->order) {
case AV_CHANNEL_ORDER_CUSTOM:
return channel_layout->u.map[idx].id;
case AV_CHANNEL_ORDER_AMBISONIC: {
int ambi_channels = channel_layout->nb_channels - av_popcount64(channel_layout->u.mask);
if (idx < ambi_channels)
return AV_CHAN_AMBISONIC_BASE + idx;
idx -= ambi_channels;
}
// fall-through
case AV_CHANNEL_ORDER_NATIVE:
for (i = 0; i < 64; i++) {
if ((1ULL << i) & channel_layout->u.mask && !idx--)
@ -674,12 +835,20 @@ int av_channel_layout_index_from_channel(const AVChannelLayout *channel_layout,
if (channel_layout->u.map[i].id == channel)
return i;
return AVERROR(EINVAL);
case AV_CHANNEL_ORDER_AMBISONIC:
case AV_CHANNEL_ORDER_NATIVE: {
uint64_t mask = channel_layout->u.mask;
int ambi_channels = channel_layout->nb_channels - av_popcount64(mask);
if (channel_layout->order == AV_CHANNEL_ORDER_AMBISONIC &&
channel >= AV_CHAN_AMBISONIC_BASE) {
if (channel - AV_CHAN_AMBISONIC_BASE >= ambi_channels)
return AVERROR(EINVAL);
return channel - AV_CHAN_AMBISONIC_BASE;
}
if ((unsigned)channel > 63 || !(mask & (1ULL << channel)))
return AVERROR(EINVAL);
mask &= (1ULL << channel) - 1;
return av_popcount64(mask);
return av_popcount64(mask) + ambi_channels;
}
default:
return AVERROR(EINVAL);
@ -711,6 +880,7 @@ int av_channel_layout_index_from_string(const AVChannelLayout *channel_layout,
return i;
}
// fall-through
case AV_CHANNEL_ORDER_AMBISONIC:
case AV_CHANNEL_ORDER_NATIVE:
ch = av_channel_from_string(str);
if (ch == AV_CHAN_NONE)
@ -737,6 +907,9 @@ int av_channel_layout_check(const AVChannelLayout *channel_layout)
return 0;
}
return 1;
case AV_CHANNEL_ORDER_AMBISONIC:
/* If non-diegetic channels are present, ensure they are taken into account */
return av_popcount64(channel_layout->u.mask) < channel_layout->nb_channels;
case AV_CHANNEL_ORDER_UNSPEC:
return 1;
default:
@ -761,7 +934,8 @@ int av_channel_layout_compare(const AVChannelLayout *chl, const AVChannelLayout
return 0;
/* can compare masks directly */
if (chl->order != AV_CHANNEL_ORDER_CUSTOM &&
if ((chl->order == AV_CHANNEL_ORDER_NATIVE ||
chl->order == AV_CHANNEL_ORDER_AMBISONIC) &&
chl->order == chl1->order)
return chl->u.mask != chl1->u.mask;

52
libavutil/channel_layout.h
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@ -79,6 +79,23 @@ enum AVChannel {
/** Channel contains data, but its position is unknown. */
AV_CHAN_UNKNOWN = 0x300,
/**
* Range of channels between AV_CHAN_AMBISONIC_BASE and
* AV_CHAN_AMBISONIC_END represent Ambisonic components using the ACN system.
*
* Given a channel id <i> between AV_CHAN_AMBISONIC_BASE and
* AV_CHAN_AMBISONIC_END (inclusive), the ACN index of the channel <n> is
* <n> = <i> - AV_CHAN_AMBISONIC_BASE.
*
* @note these values are only used for AV_CHANNEL_ORDER_CUSTOM channel
* orderings, the AV_CHANNEL_ORDER_AMBISONIC ordering orders the channels
* implicitly by their position in the stream.
*/
AV_CHAN_AMBISONIC_BASE = 0x400,
// leave space for 1024 ids, which correspond to maximum order-32 harmonics,
// which should be enough for the foreseeable use cases
AV_CHAN_AMBISONIC_END = 0x7ff,
};
enum AVChannelOrder {
@ -100,6 +117,29 @@ enum AVChannelOrder {
* channels at arbitrary positions.
*/
AV_CHANNEL_ORDER_CUSTOM,
/**
* The audio is represented as the decomposition of the sound field into
* spherical harmonics. Each channel corresponds to a single expansion
* component. Channels are ordered according to ACN (Ambisonic Channel
* Number).
*
* The channel with the index n in the stream contains the spherical
* harmonic of degree l and order m given by
* @code{.unparsed}
* l = floor(sqrt(n)),
* m = n - l * (l + 1).
* @endcode
*
* Conversely given a spherical harmonic of degree l and order m, the
* corresponding channel index n is given by
* @code{.unparsed}
* n = l * (l + 1) + m.
* @endcode
*
* Normalization is assumed to be SN3D (Schmidt Semi-Normalization)
* as defined in AmbiX format $ 2.1.
*/
AV_CHANNEL_ORDER_AMBISONIC,
};
@ -266,7 +306,8 @@ typedef struct AVChannelLayout {
*/
union {
/**
* This member must be used for AV_CHANNEL_ORDER_NATIVE.
* This member must be used for AV_CHANNEL_ORDER_NATIVE, and may be used
* for AV_CHANNEL_ORDER_AMBISONIC to signal non-diegetic channels.
* It is a bitmask, where the position of each set bit means that the
* AVChannel with the corresponding value is present.
*
@ -288,6 +329,11 @@ typedef struct AVChannelLayout {
* I.e. when map[i].id is equal to AV_CHAN_FOO, then AV_CH_FOO is the
* i-th channel in the audio data.
*
* When map[i].id is in the range between AV_CHAN_AMBISONIC_BASE and
* AV_CHAN_AMBISONIC_END (inclusive), the channel contains an ambisonic
* component with ACN index (as defined above)
* n = map[i].id - AV_CHAN_AMBISONIC_BASE.
*
* map[i].name may be filled with a 0-terminated string, in which case
* it will be used for the purpose of identifying the channel with the
* convenience functions below. Otherise it must be zeroed.
@ -333,6 +379,8 @@ typedef struct AVChannelLayout {
#define AV_CHANNEL_LAYOUT_HEXADECAGONAL AV_CHANNEL_LAYOUT_MASK(16, AV_CH_LAYOUT_HEXADECAGONAL)
#define AV_CHANNEL_LAYOUT_STEREO_DOWNMIX AV_CHANNEL_LAYOUT_MASK(2, AV_CH_LAYOUT_STEREO_DOWNMIX)
#define AV_CHANNEL_LAYOUT_22POINT2 AV_CHANNEL_LAYOUT_MASK(24, AV_CH_LAYOUT_22POINT2)
#define AV_CHANNEL_LAYOUT_AMBISONIC_FIRST_ORDER \
{ .order = AV_CHANNEL_ORDER_AMBISONIC, .nb_channels = 4, .u = { .mask = 0 }}
struct AVBPrint;
@ -532,6 +580,8 @@ int av_channel_layout_from_mask(AVChannelLayout *channel_layout, uint64_t mask);
* - a decimal or hexadecimal value of a native channel layout (eg. "4" or "0x4")
* - the number of channels with default layout (eg. "4c")
* - the number of unordered channels (eg. "4C" or "4 channels")
* - the ambisonic order followed by optional non-diegetic channels (eg.
* "ambisonic 2+stereo")
*
* @param channel_layout input channel layout
* @param str string describing the channel layout

40
libavutil/tests/channel_layout.c
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@ -79,6 +79,10 @@ int main(void)
printf("With AV_CHAN_FRONT_RIGHT: %26s\n", bp.str);
CHANNEL_NAME(63);
printf("With 63: %43s\n", bp.str);
CHANNEL_NAME(AV_CHAN_AMBISONIC_BASE);
printf("With AV_CHAN_AMBISONIC_BASE: %23s\n", bp.str);
CHANNEL_NAME(AV_CHAN_AMBISONIC_END);
printf("With AV_CHAN_AMBISONIC_END: %24s\n", bp.str);
printf("Testing av_channel_description\n");
CHANNEL_DESCRIPTION(AV_CHAN_FRONT_LEFT);
@ -87,11 +91,17 @@ int main(void)
printf("With AV_CHAN_FRONT_RIGHT: %26s\n", bp.str);
CHANNEL_DESCRIPTION(63);
printf("With 63: %43s\n", bp.str);
CHANNEL_DESCRIPTION(AV_CHAN_AMBISONIC_BASE);
printf("With AV_CHAN_AMBISONIC_BASE: %23s\n", bp.str);
CHANNEL_DESCRIPTION(AV_CHAN_AMBISONIC_END);
printf("With AV_CHAN_AMBISONIC_END: %24s\n", bp.str);
printf("\nTesting av_channel_from_string\n");
printf("With \"FL\": %41d\n", av_channel_from_string("FL"));
printf("With \"FR\": %41d\n", av_channel_from_string("FR"));
printf("With \"USR63\": %38d\n", av_channel_from_string("USR63"));
printf("With \"AMBI0\": %38d\n", av_channel_from_string("AMBI0"));
printf("With \"AMBI1023\": %35d\n", av_channel_from_string("AMBI1023"));
printf("\n==Native layouts==\n");
@ -194,6 +204,8 @@ int main(void)
printf("With \"FL+FR+FC+BL+BR+LFE\": %34s\n", bp.str);
CHANNEL_LAYOUT_FROM_STRING("2 channels (FR+FL)");
printf("With \"2 channels (FR+FL)\": %34s\n", bp.str);
CHANNEL_LAYOUT_FROM_STRING("ambisonic 1+FR+FL");
printf("With \"ambisonic 1+FR+FL\": %35s\n", bp.str);
CHANNEL_LAYOUT_FROM_STRING("FL@Foo+FR@Bar");
printf("With \"FL@Foo+FR@Bar\": %39s\n", bp.str);
CHANNEL_LAYOUT_FROM_STRING("FR+FL@Foo+USR63@Foo");
@ -259,6 +271,34 @@ int main(void)
CHANNEL_LAYOUT_CHANNEL_FROM_INDEX(3);
printf("On \"FR+FL@Foo+USR63@Foo\" layout with 3: %21d\n", ret);
printf("\n==Ambisonic layouts==\n");
printf("\nTesting av_channel_layout_from_string\n");
CHANNEL_LAYOUT_FROM_STRING("ambisonic 1");
printf("With \"ambisonic 1\": %41s\n", bp.str);
CHANNEL_LAYOUT_FROM_STRING("ambisonic 2+stereo");
printf("With \"ambisonic 2+stereo\": %34s\n", bp.str);
printf("\nTesting av_channel_layout_index_from_channel\n");
CHANNEL_LAYOUT_INDEX_FROM_CHANNEL(AV_CHAN_AMBISONIC_BASE);
printf("On \"ambisonic 2+stereo\" layout with AV_CHAN_AMBISONIC_BASE: %d\n", ret);
CHANNEL_LAYOUT_INDEX_FROM_CHANNEL(AV_CHAN_FRONT_LEFT);
printf("On \"ambisonic 2+stereo\" layout with AV_CHAN_FRONT_LEFT: %5d\n", ret);
CHANNEL_LAYOUT_INDEX_FROM_CHANNEL(AV_CHAN_FRONT_RIGHT);
printf("On \"ambisonic 2+stereo\" layout with AV_CHAN_FRONT_RIGHT: %4d\n", ret);
CHANNEL_LAYOUT_INDEX_FROM_CHANNEL(AV_CHAN_BACK_CENTER);
printf("On \"ambisonic 2+stereo\" layout with AV_CHAN_BACK_CENTER: %4d\n", ret);
printf("\nTesting av_channel_layout_channel_from_index\n");
CHANNEL_LAYOUT_CHANNEL_FROM_INDEX(0);
printf("On \"ambisonic 2+stereo\" layout with 0: %22d\n", ret);
CHANNEL_LAYOUT_CHANNEL_FROM_INDEX(9);
printf("On \"ambisonic 2+stereo\" layout with 9: %22d\n", ret);
CHANNEL_LAYOUT_CHANNEL_FROM_INDEX(10);
printf("On \"ambisonic 2+stereo\" layout with 10: %21d\n", ret);
CHANNEL_LAYOUT_CHANNEL_FROM_INDEX(11);
printf("On \"ambisonic 2+stereo\" layout with 11: %21d\n", ret);
av_channel_layout_uninit(&layout);
av_bprint_finalize(&bp, NULL);

25
tests/ref/fate/channel_layout
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@ -2,15 +2,21 @@ Testing av_channel_name
With AV_CHAN_FRONT_LEFT: FL
With AV_CHAN_FRONT_RIGHT: FR
With 63: USR63
With AV_CHAN_AMBISONIC_BASE: AMBI0
With AV_CHAN_AMBISONIC_END: AMBI1023
Testing av_channel_description
With AV_CHAN_FRONT_LEFT: front left
With AV_CHAN_FRONT_RIGHT: front right
With 63: user 63
With AV_CHAN_AMBISONIC_BASE: ambisonic ACN 0
With AV_CHAN_AMBISONIC_END: ambisonic ACN 1023
Testing av_channel_from_string
With "FL": 0
With "FR": 1
With "USR63": 63
With "AMBI0": 1024
With "AMBI1023": 2047
==Native layouts==
@ -71,6 +77,7 @@ On 5.1(side) layout with "BC": -1
Testing av_channel_layout_from_string
With "FL+FR+FC+BL+BR+LFE": 6 channels (FL+FR+FC+BL+BR+LFE)
With "2 channels (FR+FL)": 2 channels (FR+FL)
With "ambisonic 1+FR+FL": ambisonic 1+2 channels (FR+FL)
With "FL@Foo+FR@Bar": 2 channels (FL@Foo+FR@Bar)
With "FR+FL@Foo+USR63@Foo": 3 channels (FR+FL@Foo+USR63@Foo)
@ -107,3 +114,21 @@ On "FR+FL@Foo+USR63@Foo" layout with 0: 1
On "FR+FL@Foo+USR63@Foo" layout with 1: 0
On "FR+FL@Foo+USR63@Foo" layout with 2: 63
On "FR+FL@Foo+USR63@Foo" layout with 3: -1
==Ambisonic layouts==
Testing av_channel_layout_from_string
With "ambisonic 1": ambisonic 1
With "ambisonic 2+stereo": ambisonic 2+stereo
Testing av_channel_layout_index_from_channel
On "ambisonic 2+stereo" layout with AV_CHAN_AMBISONIC_BASE: 0
On "ambisonic 2+stereo" layout with AV_CHAN_FRONT_LEFT: 9
On "ambisonic 2+stereo" layout with AV_CHAN_FRONT_RIGHT: 10
On "ambisonic 2+stereo" layout with AV_CHAN_BACK_CENTER: -1
Testing av_channel_layout_channel_from_index
On "ambisonic 2+stereo" layout with 0: 1024
On "ambisonic 2+stereo" layout with 9: 0
On "ambisonic 2+stereo" layout with 10: 1
On "ambisonic 2+stereo" layout with 11: -1

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