Before this change, it was possible to overflow pic_order_cnt_lsb and
generate a stream with invalid POC numbering. This makes sure that
the field is large enough that a single IDR B* P sequence uses fewer
than half the available POC lsb values.
---
libavcodec/vaapi_encode_h264.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/libavcodec/vaapi_encode_h264.c b/libavcodec/vaapi_encode_h264.c
index deb99a7d2..74e7cb1c1 100644
--- a/libavcodec/vaapi_encode_h264.c
+++ b/libavcodec/vaapi_encode_h264.c
@@ -800,6 +800,8 @@ static int
vaapi_encode_h264_init_sequence_params(AVCodecContext *avctx)
vseq->seq_fields.bits.direct_8x8_inference_flag = 1;
vseq->seq_fields.bits.log2_max_frame_num_minus4 = 4;
vseq->seq_fields.bits.pic_order_cnt_type = 0;
+ vseq->seq_fields.bits.log2_max_pic_order_cnt_lsb_minus4 =
+ av_clip(av_log2(avctx->max_b_frames + 1) - 2, 0, 12);
if (avctx->width != ctx->surface_width ||
avctx->height != ctx->surface_height) {
--
2.11.0
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