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[79.124.17.100]) by mx.google.com with ESMTP id i30si2739235eda.530.2022.02.04.22.36.39; Fri, 04 Feb 2022 22:36:39 -0800 (PST) Received-SPF: pass (google.com: domain of ffmpeg-devel-bounces@ffmpeg.org designates 79.124.17.100 as permitted sender) client-ip=79.124.17.100; Authentication-Results: mx.google.com; dkim=neutral (body hash did not verify) header.i=@gmail.com header.s=20210112 header.b=PcOm1Z4J; spf=pass (google.com: domain of ffmpeg-devel-bounces@ffmpeg.org designates 79.124.17.100 as permitted sender) smtp.mailfrom=ffmpeg-devel-bounces@ffmpeg.org; dmarc=fail (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 5758A68B350; Sat, 5 Feb 2022 08:36:36 +0200 (EET) X-Original-To: ffmpeg-devel@ffmpeg.org Delivered-To: ffmpeg-devel@ffmpeg.org Received: from mail-qk1-f171.google.com (mail-qk1-f171.google.com [209.85.222.171]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id DFBD268B249 for ; Sat, 5 Feb 2022 08:36:29 +0200 (EET) Received: by mail-qk1-f171.google.com with SMTP id o10so6631140qkg.0 for ; Fri, 04 Feb 2022 22:36:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=BuLT9bY1lE5p5mlJ1W7KdqYJtANcbOtql1B6COyiD7s=; b=PcOm1Z4JmNQ57AitV2kDaYoYClcHiR0V6oQRkEHXFlu02UEf8/GVjiEJ4UNLiC74ph 8w2WS5Pk7J9xLkMggwYQqDOXwk/txn2PgxJ29jLawL/253YRTc8izIg8FrwvG6Tt/bYe 44BVePdMMsxtbDntW49pM93tIKUs6+D1kSzWbxlCzhNJAs5ZTQK1l1kgBEYZFj9hIobi HoKS8k/0gdM4iMQIP8uHglbp6lds8N3fHM7CeO431uOf8gtnR4gz6sOytrqT49Q60ops bfdvtGpcsvWMtNrONhcssHgRgCi/GV1e3sNt7fv/Z2RiWCCZEFviYV+OuQPK5Ycmlkug XsyQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=BuLT9bY1lE5p5mlJ1W7KdqYJtANcbOtql1B6COyiD7s=; b=vNQ3R/BTsLyE7PVkAd0vK7W+1+hEuAGTzJ4N6VabLf+9fSQ3R51FvLLJ/BDg3m9gV3 YbwD8jR9ruvNG2kB48uZpYswNwP226VPD81rSwoVUz5Ey7IbhTZiBe/YcfHda5qoIOQk 6/g+mVVyrErj7lHZtGKWHRsyyMw4tip1ReokGojPznwVcn+Or9Qv2FjGCKIUpmJQJJHE y5rK0MCfTFkAhl56M40q07OM6p7g0NJGIlXQ7V0VIocnMX6bnpx38WHDclRhaCu2eJdi jcnEdHVE0SK7mavPhuI4mGtsuJ2h7cYz2dcyBL2lC7Lt4VHMZ/pThoVM//3AXJGmhhRD aylg== X-Gm-Message-State: AOAM533CYXU6OQg3aJkxECzCsoquv/QixDgMBakK/CRb4/R0gBHEXvtP LOvPJ+NnM3XoLxi0zTuC0UgM4n/KG56Jmw== X-Received: by 2002:a37:9a09:: with SMTP id c9mr1310141qke.251.1644042988243; Fri, 04 Feb 2022 22:36:28 -0800 (PST) Received: from localhost.localdomain ([151.200.235.219]) by smtp.gmail.com with ESMTPSA id c20sm2500594qtb.58.2022.02.04.22.36.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Feb 2022 22:36:27 -0800 (PST) From: Scott Theisen To: ffmpeg-devel@ffmpeg.org Date: Sat, 5 Feb 2022 01:36:03 -0500 Message-Id: <20220205063603.28156-1-scott.the.elm@gmail.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: References: MIME-Version: 1.0 Subject: [FFmpeg-devel] [PATCH] cbs_mpeg2_split_fragment(): cache the buffer end 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 Cc: Scott Theisen Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" X-TUID: LFxQEW91vqeq It is constant, so instead of recalculating it every time, only calculate it once. Also add a few clarifying comments. --- libavcodec/cbs_mpeg2.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/libavcodec/cbs_mpeg2.c b/libavcodec/cbs_mpeg2.c index dfea12ef1b..d3204b885a 100644 --- a/libavcodec/cbs_mpeg2.c +++ b/libavcodec/cbs_mpeg2.c @@ -144,12 +144,12 @@ static int cbs_mpeg2_split_fragment(CodedBitstreamContext *ctx, CodedBitstreamFragment *frag, int header) { - const uint8_t *start; + const uint8_t *start = frag->data; + const uint8_t * const buf_end = frag->data + frag->data_size; uint32_t start_code = -1; int err; - start = avpriv_find_start_code(frag->data, frag->data + frag->data_size, - &start_code); + start = avpriv_find_start_code(start, buf_end, &start_code); if (start_code >> 8 != 0x000001) { // No start code found. return AVERROR_INVALIDDATA; @@ -165,10 +165,9 @@ static int cbs_mpeg2_split_fragment(CodedBitstreamContext *ctx, // start code in any way (as e.g. happens when there is a // Sequence End unit at the very end of a packet). start_code = UINT32_MAX; - end = avpriv_find_start_code(start--, frag->data + frag->data_size, - &start_code); - - // start points to the byte containing the start_code_identifier + end = avpriv_find_start_code(start, buf_end, &start_code); + start--; + // decrement so start points to the byte containing the start_code_identifier // (may be the last byte of fragment->data); end points to the byte // following the byte containing the start code identifier (or to // the end of fragment->data). @@ -178,6 +177,7 @@ static int cbs_mpeg2_split_fragment(CodedBitstreamContext *ctx, unit_size = (end - 4) - start; } else { // We didn't find a start code, so this is the final unit. + // There is no start code to remove from end, hence not (end - 4). unit_size = end - start; }