From 2282ea1f672054af89495359cb102ad1765f108e Mon Sep 17 00:00:00 2001 From: Gabriele Sales Date: Wed, 17 Feb 2021 16:18:49 +0100 Subject: [PATCH] Fix test for complete frame in MxPEG decoder When mb_count is not a multiple of 8, the last byte in the mxm_bitmask will never have an 0xFF value. Indeed, only (mb_count % 8) bits will be used to track which MCUs are included in the frame. This commit introduces a specific test to be used in case (mb_count % 8) != 0. It requires that only (mb_count % 8) bits are set to declare the frame complete. --- libavcodec/mxpegdec.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/libavcodec/mxpegdec.c b/libavcodec/mxpegdec.c index 763ce5871d..5c5b879f22 100644 --- a/libavcodec/mxpegdec.c +++ b/libavcodec/mxpegdec.c @@ -128,12 +128,20 @@ static int mxpeg_decode_mxm(MXpegDecodeContext *s, s->got_mxm_bitmask = 1; if (!s->has_complete_frame) { + if (mb_count % 8) + bitmask_size--; + uint8_t completion_check = 0xFF; for (i = 0; i < bitmask_size; ++i) { s->completion_bitmask[i] |= s->mxm_bitmask[i]; completion_check &= s->completion_bitmask[i]; } s->has_complete_frame = !(completion_check ^ 0xFF); + + if (s->has_complete_frame && mb_count % 8) { + completion_check = 0xFF << (8 - (mb_count % 8)); + s->has_complete_frame = !(s->mxm_bitmask[i] ^ completion_check); + } } return 0; -- 2.30.1