[FFmpeg-devel] [PATCH 07/12] lpc: remove VLA in ff_lpc_compute_autocorr

[Måns Rullgård]

Justin Ruggles <justin.ruggles at gmail.com> writes:

> Mans Rullgard wrote:
>
>> ---
>>  libavcodec/lpc.c |    4 +++-
>>  1 files changed, 3 insertions(+), 1 deletions(-)
>> 
>> diff --git a/libavcodec/lpc.c b/libavcodec/lpc.c
>> index 49e41d8..6b3cf01 100644
>> --- a/libavcodec/lpc.c
>> +++ b/libavcodec/lpc.c
>> @@ -59,7 +59,7 @@ void ff_lpc_compute_autocorr(const int32_t *data, int len, int lag,
>>                               double *autoc)
>>  {
>>      int i, j;
>> -    double tmp[len + lag + 1];
>> +    double *tmp = av_malloc((len + lag + 1) * sizeof(*tmp));
>>      double *data1= tmp + lag;
>>  
>>      apply_welch_window(data, len, data1);
>> @@ -86,6 +86,8 @@ void ff_lpc_compute_autocorr(const int32_t *data, int len, int lag,
>>          }
>>          autoc[j] = sum;
>>      }
>> +
>> +    av_free(tmp);
>>  }
>
> looks fine to me.  But I think the sse2 version of this function also
> has the same VLA.

Yes, it does, as I noticed later.  Requiring dsputil functions to
allocate unknown amounts of memory us generally a bad idea.  Can we
think of a better solution?  Make the caller pass a scratch buffer?

-- 
M?ns Rullg?rd
mans at mansr.com