Hi all,
The attached patch allows libavcodec/opus to decode ambisonics with
non-diegetic stereo stream in an ogg/opus container, as is being added in
this IETF standards draft [1].
Please let me know if there are any concerns.
Thanks,
Felicia
[1] https://tools.ietf.org/html/draft-ietf-codec-ambisonics-01#section-3.1
From 0798655323605d44d4f75e48fbfc940be0ba7423 Mon Sep 17 00:00:00 2001
From: Felicia <f...@google.com>
Date: Mon, 6 Feb 2017 15:49:36 -0800
Subject: [PATCH] libopus: decode ambisonics with non-diegetic sources
Channel mapping 2 additionally supports a non-diegetic stereo track
appended to the end of a full-order ambisonics signal, such that the
total channel count is either
(n + 1) ^ 2, or
(n + 1) ^ 2 + 2
where n is the ambisonics order
---
libavcodec/opus.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/libavcodec/opus.c b/libavcodec/opus.c
index 1eeb92c5bd..07e70fd7a4 100644
--- a/libavcodec/opus.c
+++ b/libavcodec/opus.c
@@ -373,10 +373,12 @@ av_cold int ff_opus_parse_extradata(AVCodecContext *avctx,
channel_reorder = channel_reorder_vorbis;
} else if (map_type == 2) {
int ambisonic_order = ff_sqrt(channels) - 1;
- if (channels != (ambisonic_order + 1) * (ambisonic_order + 1)) {
+ if (channels != ((ambisonic_order + 1) * (ambisonic_order + 1)) &&
+ channels != ((ambisonic_order + 1) * (ambisonic_order + 1) + 2)) {
av_log(avctx, AV_LOG_ERROR,
"Channel mapping 2 is only specified for channel counts"
- " which can be written as (n + 1)^2 for nonnegative integer n\n");
+ " which can be written as (n + 1)^2 or (n + 1)^2 + 2"
+ " for nonnegative integer n\n");
return AVERROR_INVALIDDATA;
}
layout = 0;
--
2.11.0.483.g087da7b7c-goog
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