On Thu, May 31, 2018 at 10:11:38AM +0000, Eran Kornblau wrote: > > > > -----Original Message----- > > From: ffmpeg-devel [mailto:ffmpeg-devel-boun...@ffmpeg.org] On Behalf Of > > Eran Kornblau > > Sent: Friday, May 25, 2018 4:40 PM > > To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org> > > Subject: [FFmpeg-devel] qt-faststart bug near 4GB > > > > Hi all, > > > > We encountered a rather extreme edge case with qt-faststart - we transcoded > > some video with ffmpeg, and the offset of the last video frame in the > > resulting mp4 was slightly less than 4GB. > > Since it was less than 4GB, ffmpeg used an 'stco' atom and not a 'co64' > > atom. > > When we ran qt-faststart on this file, it added the moov atom size to all > > offsets in the 'stco' atom, causing an overflow in the offsets of the > > frames close to the end of the file. The end of the video was therefore > > corrupt and could not be played. > > I think the solution here is to 'upgrade' the 'stco' atom to 'co64' if such > > an edge case happens. However, looking at the code of qt-faststart, I see > > that it doesn't actually parse the atom tree, but rather looks for the > > strings 'stco' / 'co64'. Changing 'stco' to 'co64' requires updating the > > size of all the atom in which it's contained (moov, trak, mdia etc.) > > Therefore, such a change would probably be more of a rewrite of this > > utility than a patch, so wanted to check whether anyone has any thoughts on > > this before I start writing... > > > Attaching the patch for this issue. > As expected, it required significant changes... hope you will like it :) > > Thanks! > > Eran
about the AV_WB* macros, i like them alot :) but this seems not to apply cleanly: Applying: qt-faststart - stco offset bug fix Using index info to reconstruct a base tree... M tools/qt-faststart.c Falling back to patching base and 3-way merge... Auto-merging tools/qt-faststart.c CONFLICT (content): Merge conflict in tools/qt-faststart.c error: Failed to merge in the changes. Patch failed at 0001 qt-faststart - stco offset bug fix Use 'git am --show-current-patch' to see the failed patch When you have resolved this problem, run "git am --continue". If you prefer to skip this patch, run "git am --skip" instead. To restore the original branch and stop patching, run "git am --abort". [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Into a blind darkness they enter who follow after the Ignorance, they as if into a greater darkness enter who devote themselves to the Knowledge alone. -- Isha Upanishad
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