[FFmpeg-devel] [PATCH] avformat/ivf: Change the length field to 32 bits

[Carl Eugen Hoyos]

Am Di., 1. Okt. 2019 um 21:35 Uhr schrieb Raphaël Zumer <rzumer at tebako.net>:
>
> On Tue, 2019-10-01 at 20:09 +0100, Derek Buitenhuis wrote:
> > On 01/10/2019 18:25, James Almer wrote:
> > > The value in the unused field will be 0xFFFFFFFF after this change
> > > instead of 0, since you're writing 32 bits as duration instead of
> > > 64
> > > where the high 32 bits (corresponding to the unused field) are
> > > zeroed.
> > > That means the ivf demuxer prior to this patch will read bogus
> > > duration
> > > values from ivf files created after this patch.
> > >
> > > Just leave the muxer as is.
> >
> > Why not just write zero?
> >
> > It's, to me, worse to leave a bogus 64-bit write to appease bugs in
> > our
> > own demuxer. It's confusing and misleading for any readers of the
> > code.
>
> In that case I would prefer changing the initial written value to 0
> rather than 0xFFFFFFFFFFFFFFFFULL. Writing over the unused bytes twice
> to get around an old error is a bit odd as well.

That may needlessly break non-seekable output.

Carl Eugen