[FFmpeg-devel] [PATCH 2/2] avformat/img2dec: add GEM Raster image demuxer
Peter Ross
pross at xvid.org
Sun Jan 23 06:45:02 EET 2022
On Sun, Jan 23, 2022 at 01:01:58AM +0100, Carl Eugen Hoyos wrote:
> Am Fr., 17. Sept. 2021 um 10:39 Uhr schrieb Peter Ross <pross at xvid.org>:
>
> > +static int gem_probe(const AVProbeData *p)
> > +{
> > + const uint8_t *b = p->buf;
> > + int ret = 0;
> > + if ( AV_RB16(b ) >= 1 && AV_RB16(b ) <= 3 &&
> > + AV_RB16(b + 2) >= 8 && AV_RB16(b + 2) <= 779 &&
> > + (AV_RB16(b + 4) > 0 || AV_RB16(b + 4) <= 8) &&
> > + (AV_RB16(b + 6) > 0 || AV_RB16(b + 6) <= 8) &&
> > + AV_RB16(b + 8) &&
> > + AV_RB16(b + 10) &&
> > + AV_RB16(b + 12) &&
> > + AV_RB16(b + 14)) {
> > + ret = AVPROBE_SCORE_EXTENSION / 4;
>
> Without running probetest, this score looks too high to me.
> (1, 2 or 3 followed by anything not 0 with some restrictions?)
The probetest warning is only triggered when the score is greater than
AVPROBE_SCORE_EXTENSION / 4
This score is consistent with other image2 demuxers like bmp and pcx.
How much lower does it need to be?
> Why is the above sufficient? Are there files in the wild
> without the fourcc's below?
Correct, not all files have the fourcc's below.
> > + if (AV_RN32(b + 16) == AV_RN32("STTT") ||
> > + AV_RN32(b + 16) == AV_RN32("TIMG") ||
> > + AV_RN32(b + 16) == AV_RN32("XIMG"))
> > + ret += 1;
>
> Should be EXTENSION + 1
Agree.
-- Peter
(A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)
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