From 2c7a525415fb50f7fba7f5bfb794b982915af9d4 Mon Sep 17 00:00:00 2001 From: Paul B Mahol Date: Sat, 24 Aug 2019 18:03:46 +0200 Subject: [PATCH 2/2] avformat/dhav: handle files missing data at start Try to seek to end of file and if signature is found seek backwards until last valid chunk is found. --- libavformat/dhav.c | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) diff --git a/libavformat/dhav.c b/libavformat/dhav.c index c80246c4e9..dac11df6c4 100644 --- a/libavformat/dhav.c +++ b/libavformat/dhav.c @@ -73,15 +73,30 @@ static int dhav_read_header(AVFormatContext *s) ffio_ensure_seekback(s->pb, 5); avio_read(s->pb, signature, sizeof(signature)); - if (!memcmp(signature, "DAHUA", 5)) + if (!memcmp(signature, "DAHUA", 5)) { avio_skip(s->pb, 0x400 - 5); - else - avio_seek(s->pb, -5, SEEK_CUR); + dhav->last_good_pos = avio_tell(s->pb); + } else { + if (!memcmp(signature, "DHAV", 4)) { + avio_seek(s->pb, -5, SEEK_CUR); + dhav->last_good_pos = avio_tell(s->pb); + } else if (s->pb->seekable) { + avio_seek(s->pb, avio_size(s->pb) - 8, SEEK_SET); + while (avio_rl32(s->pb) == MKTAG('d','h','a','v')) { + int seek_back; + + seek_back = avio_rl32(s->pb) + 8; + dhav->last_good_pos = avio_tell(s->pb); + if (dhav->last_good_pos < seek_back) + break; + avio_seek(s->pb, -seek_back, SEEK_CUR); + } + } + } s->ctx_flags |= AVFMTCTX_NOHEADER; dhav->video_stream_index = -1; dhav->audio_stream_index = -1; - dhav->last_good_pos = avio_tell(s->pb); return 0; } -- 2.22.0