diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index cff7f0cb54..6abb5412de 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -2162,30 +2162,26 @@ static int mkv_parse_video_projection(AVStream *st, const MatroskaTrack *track,
                                       void *logctx)
 {
     AVSphericalMapping *spherical;
+    const MatroskaTrackVideoProjection *mkv_projection = &track->video.projection;
+    const uint8_t *priv_data = mkv_projection->private.data;
     enum AVSphericalProjection projection;
     size_t spherical_size;
     uint32_t l = 0, t = 0, r = 0, b = 0;
     uint32_t padding = 0;
     int ret;
-    GetByteContext gb;
 
-    bytestream2_init(&gb, track->video.projection.private.data,
-                     track->video.projection.private.size);
-
-    if (bytestream2_get_byte(&gb) != 0) {
+    if (mkv_projection->private.size && priv_data[0] != 0) {
         av_log(logctx, AV_LOG_WARNING, "Unknown spherical metadata\n");
         return 0;
     }
 
-    bytestream2_skip(&gb, 3); // flags
-
     switch (track->video.projection.type) {
     case MATROSKA_VIDEO_PROJECTION_TYPE_EQUIRECTANGULAR:
         if (track->video.projection.private.size == 20) {
-            t = bytestream2_get_be32(&gb);
-            b = bytestream2_get_be32(&gb);
-            l = bytestream2_get_be32(&gb);
-            r = bytestream2_get_be32(&gb);
+            t = AV_RB32(priv_data +  4);
+            b = AV_RB32(priv_data +  8);
+            l = AV_RB32(priv_data + 12);
+            r = AV_RB32(priv_data + 16);
 
             if (b >= UINT_MAX - t || r >= UINT_MAX - l) {
                 av_log(logctx, AV_LOG_ERROR,
@@ -2209,14 +2205,14 @@ static int mkv_parse_video_projection(AVStream *st, const MatroskaTrack *track,
             av_log(logctx, AV_LOG_ERROR, "Missing projection private properties\n");
             return AVERROR_INVALIDDATA;
         } else if (track->video.projection.private.size == 12) {
-            uint32_t layout = bytestream2_get_be32(&gb);
+            uint32_t layout = AV_RB32(priv_data + 4);
             if (layout) {
                 av_log(logctx, AV_LOG_WARNING,
                        "Unknown spherical cubemap layout %"PRIu32"\n", layout);
                 return 0;
             }
             projection = AV_SPHERICAL_CUBEMAP;
-            padding = bytestream2_get_be32(&gb);
+            padding = AV_RB32(priv_data + 8);
         } else {
             av_log(logctx, AV_LOG_ERROR, "Unknown spherical metadata\n");
             return AVERROR_INVALIDDATA;