From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTP id 4880C468E5 for ; Sun, 22 Oct 2023 21:51:51 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 7727768CA60; Mon, 23 Oct 2023 00:51:25 +0300 (EEST) Received: from relay7-d.mail.gandi.net (relay7-d.mail.gandi.net [217.70.183.200]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 7129068C65F for ; Mon, 23 Oct 2023 00:51:17 +0300 (EEST) Received: by mail.gandi.net (Postfix) with ESMTPSA id C8D8320003 for ; Sun, 22 Oct 2023 21:51:16 +0000 (UTC) From: Michael Niedermayer To: FFmpeg development discussions and patches Date: Sun, 22 Oct 2023 23:51:08 +0200 Message-Id: <20231022215113.3469-4-michael@niedermayer.cc> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20231022215113.3469-1-michael@niedermayer.cc> References: <20231022215113.3469-1-michael@niedermayer.cc> X-GND-Sasl: michael@niedermayer.cc Subject: [FFmpeg-devel] [PATCH 4/9] avcodec/vlc: Replace mysterious max computation code in multi vlc X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: Signed-off-by: Michael Niedermayer --- libavcodec/vlc.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/libavcodec/vlc.c b/libavcodec/vlc.c index 65883a506ff..9b7a42f79a3 100644 --- a/libavcodec/vlc.c +++ b/libavcodec/vlc.c @@ -359,7 +359,7 @@ static void add_level(VLC_MULTI_ELEM *table, const int is16bit, unsigned* levelcnt, VLC_MULTI_ELEM *info) { int max_symbols = VLC_MULTI_MAX_SYMBOLS >> is16bit; - for (int i = num-1; i > max; i--) { + for (int i = num-1; i >= max; i--) { for (int j = 0; j < 2; j++) { int newlimit, sym; int t = j ? i-1 : i; @@ -398,7 +398,7 @@ static int vlc_multi_gen(VLC_MULTI_ELEM *table, const VLC *single, const int is16bit, const int nb_codes, const int numbits, VLCcode *buf, void *logctx) { - int minbits, maxbits, max = nb_codes-1; + int minbits, maxbits, max; unsigned count[VLC_MULTI_MAX_SYMBOLS-1] = { 0, }; VLC_MULTI_ELEM info = { { 0, }, 0, 0, }; int count0 = 0; @@ -419,10 +419,13 @@ static int vlc_multi_gen(VLC_MULTI_ELEM *table, const VLC *single, } av_assert0(maxbits <= numbits); - while (max >= nb_codes/2) { - if (buf[max].bits+minbits > maxbits) + for (max = nb_codes; max > nb_codes - count0; max--) { + // We can only add a code that fits with the shortest other code into the table + // We assume the table is sorted by bits and we skip subtables which from our + // point of view are basically random corrupted entries + // If we have not a single useable vlc we end with max = nb_codes + if (buf[max - 1].bits+minbits > numbits) break; - max--; } for (int j = 0; j < 1<