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 ESMTPS id 1210E456B8 for ; Sun, 19 Jan 2025 10:37:26 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 3FF5A68B537; Sun, 19 Jan 2025 12:37:04 +0200 (EET) Received: from vidala.pars.ee (vidala.pars.ee [116.203.72.101]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id E7F4368B44A for ; Sun, 19 Jan 2025 12:37:01 +0200 (EET) DKIM-Signature: v=1; a=rsa-sha256; s=202405r; d=lynne.ee; c=relaxed/relaxed; h=Message-ID:Date:Subject:To:From; t=1737283021; bh=yQvH+nGKiOLK0WdosZDu0rN E5XSdpceLDE8gzI5CccQ=; b=A48vyPx6qn53qL4nXeKLxLdrf9SmSHZ9awWEkb8CNomXcqpyzO tE+SZVvq2kgS4dSd8xyqu+cF1F7r9cLkVe1lQVifDLtM6VpA6wofABxi6qSXTiXiNwk0Ch5cpJQ E4MXM/2k9/I2MFv/TMDTgD8OJEJ0LJv/dUMFZNfjiJMFZCAx9ZzDCguqYd5dpiwrb0wBJaZV4Ya mbCM0vUZjDTj9/5EEzUDNPQ/4DHnPTYrPsj6/7XACm3P/AKrgwGVOUTBTGrtWp/v+Vq98US5ev5 Z24sLG/MsaZTT8oOm4TNIQWhfE5Im4aeu9yAV2hHIWwlFxXzroylku0PefAzVbdNb7A==; DKIM-Signature: v=1; a=ed25519-sha256; s=202405e; d=lynne.ee; c=relaxed/relaxed; h=Message-ID:Date:Subject:To:From; t=1737283021; bh=yQvH+nGKiOLK0WdosZDu0rN E5XSdpceLDE8gzI5CccQ=; b=3bZbaij7PZXPlH5uoKxENyU15s7I0FQou4lNFXkEMiRVhNd6Sz Zs0Qs9SM7EWH9QgGUzykv8b3/pl3bU66xEAQ==; From: Lynne To: ffmpeg-devel@ffmpeg.org Date: Sun, 19 Jan 2025 19:36:21 +0900 Message-ID: <20250119103640.1224690-3-dev@lynne.ee> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250119103640.1224690-1-dev@lynne.ee> References: <20250119103640.1224690-1-dev@lynne.ee> MIME-Version: 1.0 Subject: [FFmpeg-devel] [PATCH 03/12] ffv1dec: move slice start finding into a function 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: Lynne 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: This also cleans up and gives the code some much needed comments. --- libavcodec/ffv1dec.c | 66 +++++++++++++++++++++++++++++++------------- 1 file changed, 47 insertions(+), 19 deletions(-) diff --git a/libavcodec/ffv1dec.c b/libavcodec/ffv1dec.c index b7f235c47f..aa988571bc 100644 --- a/libavcodec/ffv1dec.c +++ b/libavcodec/ffv1dec.c @@ -866,6 +866,38 @@ static av_cold int decode_init(AVCodecContext *avctx) return 0; } +static int find_next_slice(AVCodecContext *avctx, + uint8_t *buf, uint8_t *buf_end, int idx, + uint8_t **pos, uint32_t *len) +{ + FFV1Context *f = avctx->priv_data; + + /* Length field */ + uint32_t v = buf_end - buf; + if (idx || f->version > 2) { + /* Three bytes of length, plus flush bit + CRC */ + uint32_t trailer = 3 + 5*!!f->ec; + if (trailer > buf_end - buf) + v = INT_MAX; + else + v = AV_RB24(buf_end - trailer) + trailer; + } + + if (buf_end - buf < v) { + av_log(avctx, AV_LOG_ERROR, "Slice pointer chain broken\n"); + ff_progress_frame_report(&f->picture, INT_MAX); + return AVERROR_INVALIDDATA; + } + + *len = v; + if (idx) + *pos = buf_end - v; + else + *pos = buf; + + return 0; +} + static int decode_frame(AVCodecContext *avctx, AVFrame *rframe, int *got_frame, AVPacket *avpkt) { @@ -875,7 +907,7 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *rframe, RangeCoder *const c = &f->slices[0].c; int ret, key_frame; uint8_t keystate = 128; - uint8_t *buf_p; + uint8_t *buf_end; AVFrame *p; ff_progress_frame_unref(&f->last_picture); @@ -941,27 +973,23 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *rframe, ff_thread_finish_setup(avctx); - buf_p = buf + buf_size; + buf_end = buf + buf_size; for (int i = f->slice_count - 1; i >= 0; i--) { FFV1SliceContext *sc = &f->slices[i]; - int trailer = 3 + 5*!!f->ec; - int v; - sc->slice_damaged = 0; + uint8_t *pos; + uint32_t len; + int err = find_next_slice(avctx, buf, buf_end, i, + &pos, &len); + if (err < 0) + return err; - if (i || f->version > 2) { - if (trailer > buf_p - buf) v = INT_MAX; - else v = AV_RB24(buf_p-trailer) + trailer; - } else v = buf_p - c->bytestream_start; - if (buf_p - c->bytestream_start < v) { - av_log(avctx, AV_LOG_ERROR, "Slice pointer chain broken\n"); - ff_progress_frame_report(&f->picture, INT_MAX); - return AVERROR_INVALIDDATA; - } - buf_p -= v; + buf_end -= len; + + sc->slice_damaged = 0; if (f->ec) { - unsigned crc = av_crc(av_crc_get_table(AV_CRC_32_IEEE), f->crcref, buf_p, v); + unsigned crc = av_crc(av_crc_get_table(AV_CRC_32_IEEE), f->crcref, pos, len); if (crc != f->crcref) { int64_t ts = avpkt->pts != AV_NOPTS_VALUE ? avpkt->pts : avpkt->dts; av_log(f->avctx, AV_LOG_ERROR, "slice CRC mismatch %X!", crc); @@ -975,15 +1003,15 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *rframe, slice_set_damaged(f, sc); } if (avctx->debug & FF_DEBUG_PICT_INFO) { - av_log(avctx, AV_LOG_DEBUG, "slice %d, CRC: 0x%08"PRIX32"\n", i, AV_RB32(buf_p + v - 4)); + av_log(avctx, AV_LOG_DEBUG, "slice %d, CRC: 0x%08"PRIX32"\n", i, AV_RB32(pos + len - 4)); } } if (i) { - ff_init_range_decoder(&sc->c, buf_p, v); + ff_init_range_decoder(&sc->c, pos, len); ff_build_rac_states(&sc->c, 0.05 * (1LL << 32), 256 - 8); } else - sc->c.bytestream_end = buf_p + v; + sc->c.bytestream_end = pos + len; } -- 2.47.1 _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".