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avutil/channel_layout: factorize ambisonic order detection

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Signed-off-by: Marton Balint <cus@passwd.hu>
This commit is contained in:
Marton Balint 2022-03-15 20:16:31 +01:00
parent bd40375dd2
commit 580f7b6c3a
1 changed files with 29 additions and 10 deletions
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39
libavutil/channel_layout.c
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@ -27,6 +27,7 @@
#include <stdlib.h>
#include <string.h>
#include "avassert.h"
#include "channel_layout.h"
#include "bprint.h"
#include "common.h"
@ -644,11 +645,11 @@ int av_channel_layout_copy(AVChannelLayout *dst, const AVChannelLayout *src)
}
/**
* 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.
* If the layout is n-th order standard-order ambisonic, with optional
* extra non-diegetic channels at the end, return the order.
* Return a negative error code otherwise.
*/
static int try_describe_ambisonic(AVBPrint *bp, const AVChannelLayout *channel_layout)
static int ambisonic_order(const AVChannelLayout *channel_layout)
{
int i, highest_ambi, order;
@ -657,16 +658,18 @@ static int try_describe_ambisonic(AVBPrint *bp, const AVChannelLayout *channel_l
highest_ambi = channel_layout->nb_channels - av_popcount64(channel_layout->u.mask) - 1;
else {
const AVChannelCustom *map = channel_layout->u.map;
av_assert0(channel_layout->order == AV_CHANNEL_ORDER_CUSTOM);
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;
return AVERROR(EINVAL);
/* non-default ordering */
if (is_ambi && map[i].id - AV_CHAN_AMBISONIC_BASE != i)
return 0;
return AVERROR(EINVAL);
if (CHAN_IS_AMBI(map[i].id))
highest_ambi = i;
@ -674,17 +677,33 @@ static int try_describe_ambisonic(AVBPrint *bp, const AVChannelLayout *channel_l
}
/* no ambisonic channels*/
if (highest_ambi < 0)
return 0;
return AVERROR(EINVAL);
order = floor(sqrt(highest_ambi));
/* incomplete order - some harmonics are missing */
if ((order + 1) * (order + 1) != highest_ambi + 1)
return AVERROR(EINVAL);
return order;
}
/**
* 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 nb_ambi_channels;
int order = ambisonic_order(channel_layout);
if (order < 0)
return 0;
av_bprintf(bp, "ambisonic %d", order);
/* extra channels present */
if (highest_ambi < channel_layout->nb_channels - 1) {
nb_ambi_channels = (order + 1) * (order + 1);
if (nb_ambi_channels < channel_layout->nb_channels) {
AVChannelLayout extra = { 0 };
char buf[128];
@ -696,12 +715,12 @@ static int try_describe_ambisonic(AVBPrint *bp, const AVChannelLayout *channel_l
const AVChannelCustom *map = channel_layout->u.map;
extra.order = AV_CHANNEL_ORDER_CUSTOM;
extra.nb_channels = channel_layout->nb_channels - highest_ambi - 1;
extra.nb_channels = channel_layout->nb_channels - nb_ambi_channels;
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],
memcpy(extra.u.map, &map[nb_ambi_channels],
sizeof(*extra.u.map) * extra.nb_channels);
}