Le 27 août 2024 03:03:37 GMT+03:00, Marton Balint <c...@passwd.hu> a écrit :
>Using INFINITY can cause issues with -ffast-math, and since we only use this
>value to decide the formatting, we can just as easily use 0 for log10 of zero.
FFmpeg does not enable fast-math and last I tried it won't work at all anyway:
FATE commits seppuku by OoM.
The statement above is completely false if applied to the whole code base
rather than just this function. Notably FFMAX and FFMIN behave differently
under -fno-infinite-math (which is implied by -ffast-math).
I suspect that *this* code is just the tip of the iceberg. It's not hard to
imagine that ignoring infinities will break stuff, for one: reading raw binary
content as float can lead to infinities and other NaNs.
So IMO this patch is wrong. Either we've audited the whole code base, and then
we should enable -ffast-math, or at least -fno-infinite-math by default, or we
haven't and then we should not be papering over the issue like this.
>
>Signed-off-by: Marton Balint <c...@passwd.hu>
>---
> libavutil/timestamp.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/libavutil/timestamp.c b/libavutil/timestamp.c
>index 6c231a517d..be4540d4c8 100644
>--- a/libavutil/timestamp.c
>+++ b/libavutil/timestamp.c
>@@ -24,7 +24,7 @@ char *av_ts_make_time_string2(char *buf, int64_t ts,
>AVRational tb)
> snprintf(buf, AV_TS_MAX_STRING_SIZE, "NOPTS");
> } else {
> double val = av_q2d(tb) * ts;
>- double log = (fpclassify(val) == FP_ZERO ? -INFINITY :
>floor(log10(fabs(val))));
>+ double log = (fpclassify(val) == FP_ZERO ? 0 :
>floor(log10(fabs(val))));
> int precision = (isfinite(log) && log < 0) ? -log + 5 : 6;
> int last = snprintf(buf, AV_TS_MAX_STRING_SIZE, "%.*f", precision,
> val);
> last = FFMIN(last, AV_TS_MAX_STRING_SIZE - 1) - 1;
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
