From 580f7b6c3ac4ee196c7a78641fe65da7a68b6971 Mon Sep 17 00:00:00 2001 From: Marton Balint Date: Tue, 15 Mar 2022 20:16:31 +0100 Subject: [PATCH] avutil/channel_layout: factorize ambisonic order detection Signed-off-by: Marton Balint --- libavutil/channel_layout.c | 39 ++++++++++++++++++++++++++++---------- 1 file changed, 29 insertions(+), 10 deletions(-) diff --git a/libavutil/channel_layout.c b/libavutil/channel_layout.c index c60ccf368f..c61d612fd8 100644 --- a/libavutil/channel_layout.c +++ b/libavutil/channel_layout.c @@ -27,6 +27,7 @@ #include #include +#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); }