[FFmpeg-devel] [PATCH 1/2] libopenjpegdec: set max_lowres to UINT8_MAX

[Michael Bradshaw]

On Thu, Jul 19, 2012 at 1:20 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Wed, Jul 18, 2012 at 09:51:44PM -0600, Michael Bradshaw wrote:
>> Paul pointed out that OpenJPEG doesn't have a max lowres limit. See
>> http://ffmpeg.org/pipermail/ffmpeg-devel/2012-July/127906.html
>>
>> This removes the arbitrary limit.
>>
>> Thanks,
>>
>> Michael
>
>>  libopenjpegdec.c |    2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> bc2d62e1146b20a9da2d5cd1e86884081e7c0cd8  0001-libopenjpegdec-set-max_lowres-to-UINT8_MAX.patch
>> From 643d6db4faf35b57b8d834d4dd1db90165ad257f Mon Sep 17 00:00:00 2001
>> From: Michael Bradshaw <mbradshaw at sorensonmedia.com>
>> Date: Wed, 18 Jul 2012 21:47:33 -0600
>> Subject: [PATCH 1/2] libopenjpegdec: set max_lowres to UINT8_MAX
>>
>> OpenJPEG doesn't have a max limit, so don't enforce an arbitrary one.
>>
>> Signed-off-by: Michael Bradshaw <mbradshaw at sorensonmedia.com>
>> ---
>>  libavcodec/libopenjpegdec.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/libavcodec/libopenjpegdec.c b/libavcodec/libopenjpegdec.c
>> index 5b5d27b..31fff7c 100644
>> --- a/libavcodec/libopenjpegdec.c
>> +++ b/libavcodec/libopenjpegdec.c
>> @@ -388,7 +388,7 @@ AVCodec ff_libopenjpeg_decoder = {
>>      .close            = libopenjpeg_decode_close,
>>      .decode           = libopenjpeg_decode_frame,
>>      .capabilities     = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS,
>> -    .max_lowres       = 5,
>> +    .max_lowres       = UINT8_MAX,
>
> this is possibly problematic
>
> lowres is in log2 units, a value of 255 would dwarf the act of
> reducing a image the size of teh vissible universe with pixels as
> small as subatomic particles down to a single pixel.
> that alone wouldnt be a problem but a more realworld issue
> is that lowres is used in the form of width >> lowres and shifts
> become undefined when they exceed the number of bits of the shifted
> field, thus i would suggest that the largest limit would be 31 or
> possibly less. 31 still would allow 2147483648x2147483648 to be
> decoded as 1x1.

Hi,

I've changed to patch to use 31. The new version is attached.

Thanks,

Michael
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