[vlc-devel] [PATCH] avcodec: remove the VLC DSP mask

Rémi Denis-Courmont remi at remlab.net
Mon Feb 24 10:30:27 CET 2014

On Mon, 24 Feb 2014 10:11:35 +0100, Jean-Baptiste Kempf <jb at videolan.org>
> As far as I remember, this detection in libav never worked for non-NEON 
> cortex A9 devices, aka tegra2.

The NEON check is essentially the same in VLC and libavutil: read cpuinfo
(or auxv) on Linux, and hard-code on other kernels. This is not perfect; it
will bomb out on non-Linux kernels, but that is already the case with this
patch anyway.

Historically, libav had to be compiled with NEON disabled to run without
NEON. Masking NEON in VLC would *not* work around that.

> So, if this is still the case, this is a clear no from me.

The point is not that libav checks are perfect. The point is that they
are, depending on the platform, as good as (ARM) or better than (x86, PPC)
VLC's own checks.

Really the DSP mask stuff is legacy cruft from the time when VLC still had
--no-mmx et al run-time options on x86.

Rémi Denis-Courmont
Sent from my collocated server

More information about the vlc-devel mailing list