[FFmpeg-devel] [RFC] avcodec: Add native DCA decoder based on libdcadec.

[James Almer]

On 1/5/2016 11:21 PM, Michael Niedermayer wrote:
> On Tue, Jan 05, 2016 at 11:38:00PM +0300, foo86 wrote:
>> On Tue, Jan 05, 2016 at 08:45:22PM +0100, Andreas Cadhalpun wrote:
>>> On 03.01.2016 18:49, foo86 wrote:
>>>> +// 5.3.1 - Bit stream header
>>>> +static int parse_frame_header(DCA2CoreDecoder *s)
>>>> +{
>>> [...]
>>>> +    // Source PCM resolution
>>>> +    s->source_pcm_res = ff_dca_bits_per_sample[pcmr_index = get_bits(&s->gb, 3)];
>>>
>>> This can cause an out-of-bounds read if get_bits returns 7, because ff_dca_bits_per_sample
>>> only has 7 elements.
>>
>> Fixed locally, thanks.
>>
>> P.S. To avoid resending this huge patch, I've put the fixes accumulated
>> so far in a private dcadec2 branch on github [1] (will be rebased
>> frequently against FFmpeg master).
>>
> 
>> [1]: https://github.com/foo86/FFmpeg/tree/dcadec2
> 
> breaks "make fate", something needs to be updated
> or a new reference sample uploaded if teh one we have is wrong
> 
> stddev:  297.72 PSNR: 46.85 MAXDIFF: 3474 bytes:  8994816/  9601024
> MAXDIFF: |3474 - 0| >= 1
> size: |8994816 - 9601024| >= 0
> Test dca-xll failed. Look at tests/data/fate/dca-xll.err for details.
> make: *** [fate-dca-xll] Error 1
> make: *** Waiting for unfinished jobs....

Was this run using foo86's decoder, or the current one? If the former then it's
not unexpected since the xll test was made for the current decoder, which is not
bitexact.

Ideally, once this decoder is committed replacing the current one we'd replace
the samples for the set available here: https://github.com/foo86/dcadec-samples