[FFmpeg-devel] [PATCH] mxf umid generation

[Baptiste Coudurier]

On 3/7/2009 3:36 PM, Michael Niedermayer wrote:
> On Sat, Mar 07, 2009 at 02:48:49PM -0800, Baptiste Coudurier wrote:
>> On 3/6/2009 7:44 PM, Michael Niedermayer wrote:
>>> On Fri, Mar 06, 2009 at 07:28:55PM -0800, Baptiste Coudurier wrote:
>>>> Hi,
>>>>
>>>> It seems some products really check umid and base themself on its
>>>> uniqueness, so it seems better to actually try to generate a unique number.
>>>>
>>>> Is the approach in the patch acceptable ? If no, 
>>>
>>>
>>>> any other suggestion ?
>>> yes, add a random_seed.c/h
>>> that does:
>>> 1. try to get a uint32 from reading /dev/(u)random
>>> 2. try to get a uint32 from LSB of rdtsc (and similar for ppc/bfin see 
>>>    libavutil/timer.h)
>>> 3. md5 or sha1 of the first frame or extradata
>>>
>> Like this ?
>>
>
> [...]
> 
>> +/*
>> + * Get a seed to use in conjuction with random functions
>> + */
> 
> missing /**
> and should be in the header
> 

Done.

>> +uint32_t ff_random_get_seed(void)
>> +{
>> +    uint32_t seed;
>> +    int fd;
>> +
> 
>> +    if ((fd = open("/dev/random", O_RDONLY)) != -1) {
>> +        read(fd, &seed, 4);
>> +        close(fd);
>> +        return seed;
>> +    }
>> +    if ((fd = open("/dev/urandom", O_RDONLY)) != -1) {
>> +        read(fd, &seed, 4);
>> +        close(fd);
>> +        return seed;
>> +    }
> 
> if((fd = open("/dev/random", O_RDONLY)) == -1)
>     fd = open("/dev/urandom", O_RDONLY);
> if(fd != -1){
>     read(fd, &seed, 4);
>     close(fd);
>     return seed;
> }

Changed.

> 
>> Property changes on: libavutil\random_seed.c
>> ___________________________________________________________________
>> Added: svn:eol-style
>>    + LF
> 
> intended?
> 
> except these ok
> 

I'm not sure, I'm on windows because products I test with only works on
windows, I set ending lines style to unix, but it keeps adding this...

It should be ok I think.

Btw, is lfg ok for this purpose or should I use something else ?

-- 
Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
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FFmpeg maintainer                                  http://www.ffmpeg.org
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