[FFmpeg-devel] mjpeg and llvm-gcc
Mike Melanson
mike
Thu Jun 18 03:21:02 CEST 2009
Derk-Jan Hartman wrote:
> For VLC media player Mac OS X, we were working on using llvm-gcc for the
> new binaries. VLC and FFmpeg was behaving very well with it, but
> recently I noticed it crashed in ff_mjpeg_decode_sos() for almost all
> MJPEGs.
>
> Example file:
> http://samples.mplayerhq.hu/V-codecs/MJPEGs/angels_480-mjpegcompress.avi
>
> This file (and other mjpeg files) was producing "error dc" errors, and
> eventually crashed.
> I have been able to determine that when I switch from llvm-gcc-4.2 back
> to gcc-4.2, the crash disappeared. I have little experience trying to
> track causes to things like this, so if anyone has any tips on how to
> proceed, I would welcome them. If someone could try with llvm on Linux,
> that might be useful as well. I guess this might possibly be a compiler
> bug ? Should I try different optimization settings ?
I tried that file on a number of different configurations (including
LLVM on Linux, both 32- and 64-bit) using this command line:
ffmpeg -idct simple -i angels_480-mjpegcompress.avi -f crc -
These were my results (troubling that there are 2 sets):
=============
There were 2 unique stdout blobs collected
The following configurations agreed on the same stdout:
Linux / x86_32 / gcc 2.95.3
Linux / x86_32 / gcc 3.4.6
Linux / x86_32 / gcc 4.0.4
Linux / x86_32 / gcc 4.3.3
Linux / x86_32 / gcc 4.4.0
stdout:
CRC=0x45f16042
The following configurations agreed on the same stdout:
Linux / x86_32 / llvm-svn
Linux / x86_32 / icc 11.0
Linux / x86_32 / icc 10.1
Linux / x86_32 / gcc 4.1.2
Linux / x86_32 / gcc 4.2.4
Linux / x86_64 / llvm-svn
Linux / x86_64 / icc 11.0
Linux / x86_64 / icc 10.1
Linux / x86_64 / gcc 4.0.4
Linux / x86_64 / gcc 4.1.2
Linux / x86_64 / gcc 4.2.4
Linux / x86_64 / gcc 4.3.3
Linux / x86_64 / gcc 4.4.0
Linux / x86_64 / gcc svn
Linux / PPC / gcc 4.0.4
Linux / PPC / gcc 4.1.2
Linux / PPC / gcc 4.2.4
Linux / PPC / gcc 4.3.3
Linux / PPC / gcc 4.4.0
Mac OS X / x86_64 / gcc 4.0.1
stdout:
CRC=0x0e544952
--
-Mike Melanson
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