[FFmpeg-devel] Strange issue debugging AAC

[Robert Swain]

2008/9/18 Alex Converse <alex.converse at gmail.com>:
> On Thu, Sep 18, 2008 at 3:02 AM, Siarhei Siamashka
> <siarhei.siamashka at gmail.com> wrote:
>> On Thursday 18 September 2008, Alex Converse wrote:
>>> Hey all,
>>>
>>> I'm running into a weird issue with get_bits() in the aac decoder that
>>> I was hoping some one could help me with so that I can continue
>>> hunting down bugs.
>>>
>>> Consider the attached patch:
>>>
>>> and the test stream at
>>> http://standards.iso.org/ittf/PubliclyAvailableStandards/ISO_IEC_14496-4_20
>>>04_Conformance_Testing/audio_conformance/mpeg4audio-conformance/compressedMp
>>>4/al07_44.mp4
>>>
>>> I'm getting different results from the #if and #else sections of the
>>> code, and it's boggling my mind. Any assistance would be greatly
>>> appreciated. I've tried both gcc-3.4 and gcc-4.3.
>>
>> +    int scale_bits;
>> ...
>> +#if 1
>>     scale = pow(2., pow(2., get_bits(gb, 2) - 3));
>> +#else
>> +    scale_bits = get_bits(gb, 2);
>> +    scale = pow(2., pow(2., scale_bits - 3));
>> +#endif
>> +    av_log(ac->avccontext, AV_LOG_ERROR, "scale = %f\n", scale);
>>
>>
>> get_bits returns unsigned int, so "(double)(get_bits(gb, 2) - 3)" and
>> "(double)((int)get_bits(gb, 2) - 3)" are not identical.
>>
>
> Thanks. Trivial patch attached.

Did you intend this to be applied? I'll apply the cast, of course, but
the av_log() is undesirable for normal use. :)

Rob