From a5e93b70620bb737fb48d1d992e819a78bea1fbc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alicia=20Boya=20Garc=C3=ADa?= <aboya@igalia.com>
Date: Fri, 16 Feb 2018 23:40:50 +0100
Subject: [PATCH] matroskademux: Add comment about Opus clipping

https://bugzilla.gnome.org/show_bug.cgi?id=793523
---
 gst/matroska/matroska-demux.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/gst/matroska/matroska-demux.c b/gst/matroska/matroska-demux.c
index f3bf76366b..fa9edc7055 100644
--- a/gst/matroska/matroska-demux.c
+++ b/gst/matroska/matroska-demux.c
@@ -4057,6 +4057,13 @@ gst_matroska_demux_parse_blockgroup_or_simpleblock (GstMatroskaDemux * demux,
             GST_BUFFER_PTS (sub) -= stream->codec_delay;
           } else {
             GST_BUFFER_PTS (sub) = 0;
+
+            /* Opus GstAudioClippingMeta units are scaled by 48000/sample_rate.
+               That is, if a Opus track has audio encoded at 24000 Hz and 132
+               samples need to be clipped, GstAudioClippingMeta.start will be
+               set to 264. (This is also the case for buffer offsets.)
+               Opus sample rates are always divisors of 48000 Hz, which is the
+               maximum allowed sample rate. */
             start_clip =
                 gst_util_uint64_scale_round (stream->codec_delay, 48000,
                 GST_SECOND);