8 Mar 2019, 14:15 by d...@lynne.ee: > 7 Mar 2019, 21:22 by > mich...@niedermayer.cc > <mailto:mich...@niedermayer.cc>> : > >> On Thu, Mar 07, 2019 at 07:26:32PM +0100, Lynne wrote: >> >>> By default now, if AV_EF_CRCCHECK or AV_EF_IGNORE_ERR are enabled the >>> decoder >>> will skip the chunk and carry on with the next one. This should make the >>> >>> decoder able to decode more corrupt files because the functions which decode >>> individual chunks will very likely error out if fed invalid data and stop >>> the >>> decoding of the entire image. >>> Should this be made default? CRC verification doesn't take long even for >>> very >>> large files. >>> Also fix the length check for chunk size. It needs to take into account the >>> 4 byte tag as well as the 4 byte CRC. >>> >>> pngdec.c | 19 ++++++++++++++++++- >>> 1 file changed, 18 insertions(+), 1 deletion(-) >>> 4255c91468cee2bc2fa757fae69762ff5ee5774a >>> 0001-pngdec-add-ability-to-check-chunk-CRC.patch >>> From 7aff99d12faf557753c5ee860a9672c7a09a26e3 Mon Sep 17 00:00:00 2001 >>> From: Lynne <>> >>> d...@lynne.ee <mailto:d...@lynne.ee>>>> <mailto:>>> >>> d...@lynne.ee <mailto:d...@lynne.ee>>>> >>> > >>> Date: Thu, 7 Mar 2019 18:15:23 +0000 >>> Subject: [PATCH] pngdec: add ability to check chunk CRC >>> >>> By default now, if AV_EF_CRCCHECK or AV_EF_IGNORE_ERR are enabled the >>> decoder >>> will skip the chunk and carry on with the next one. This should make the >>> decoder able to decode more corrupt files because the functions which decode >>> individual chunks will very likely error out if fed invalid data and stop >>> the >>> decoding of the entire image. >>> Should this be made default? CRC verification doesn't take long even for >>> very >>> large files. >>> >> >> i would tend toward enabling it by default but maybe first post some >> numbers of how much this changes decode time >> > > For the largest png I found: > > https://vk.com/doc218587497_437472325?hash=51300ca9ba40f462ac&dl=1bcf9a57b0d989da1f > > <https://vk.com/doc218587497_437472325?hash=51300ca9ba40f462ac&dl=1bcf9a57b0d989da1f>> > <> > https://vk.com/doc218587497_437472325?hash=51300ca9ba40f462ac&dl=1bcf9a57b0d989da1f > > <https://vk.com/doc218587497_437472325?hash=51300ca9ba40f462ac&dl=1bcf9a57b0d989da1f>> > > > > There was no increase in decoding time, it took 2.3 seconds on my machine > with and without -err_detect crccheck. > > With -err_detect crccheck perf reported 2.52% spent in av_crc > > >>> Also fix the length check for chunk size. It needs to take into account the >>> 4 byte tag as well as the 4 byte CRC. >>> >> >> this should be a seperate patch as its unrelated >> > > removed and attached new patch file > > Maybe always enabling the CRC check isn't worth it since if you download from > the internet you could either get a full error-free file or an incomplete one > rather than a corrupt one. Maybe only for torrents with huge png files where > not all chunks have been downloaded yet, or broken hard drives, but the > ignore_err > flag could be manually enabled in those cases. >
Ping? The apedec CRC patch needs a review too. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
