[FFmpeg-devel] [PATCH 03/12] mdct: remove temporary array in ff_kbd_window_init()

Måns Rullgård mans
Thu Jun 24 02:35:06 CEST 2010

Michael Niedermayer <michaelni at gmx.at> writes:

> On Thu, Jun 24, 2010 at 12:37:34AM +0100, M?ns Rullg?rd wrote:
>> Michael Niedermayer <michaelni at gmx.at> writes:
>> > On Wed, Jun 23, 2010 at 06:26:41PM +0100, Mans Rullgard wrote:
>> >> The intermediate values can be stored in the output array, avoiding
>> >> the need for a variable-length array.
>> >
>> > this can write into static arrays and thus introduces a race condition
>> Quite.  Which would you prefer then, 1) malloc/free or, 2) always
>> allocating a [1024] array (largest size used)?  Option 2 would use 4k
>> (float) or 8k (double) of stack space, which is IMO a bit larger than
>> what's comfortable.  It would of course not change anything compared
>> to current code so should be safe.
> as its speed irrelevant init code iam ok with malloc()

Using malloc complicates error handling though.  The function
currently returns no status (since it cannot fail), and the callers
obviously do not check it.

Since allocating a 1024-element array is fine now, it should be OK
even if hardcoded.  Do you forsee larger sizes being required in the

M?ns Rullg?rd
mans at mansr.com

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