[FFmpeg-devel] [PATCH 1/2] Bink version 'b' video decoder

[Vitor Sessak]

On 02/11/2011 09:57 PM, Vitor Sessak wrote:
> On 02/11/2011 12:45 PM, Peter Ross wrote:
>> On Thu, Feb 10, 2011 at 08:16:18PM +0100, Vitor Sessak wrote:
>>> On 02/10/2011 05:26 AM, Peter Ross wrote:
>>>> On Wed, Feb 09, 2011 at 09:54:00PM +0100, Vitor Sessak wrote:
>>>>> On 02/09/2011 01:04 PM, Peter Ross wrote:
>>>>>> Based on original patch by Kostya Shishkov
>>>>>> ---
>>>>>> libavcodec/bink.c | 340
>>>>>> ++++++++++++++++++++++++++++++++++++++++++++++---
>>>>>> libavcodec/binkdata.h | 41 ++++++
>>>>>> 2 files changed, 364 insertions(+), 17 deletions(-)
>>>>>>
>>>>>> diff --git a/libavcodec/bink.c b/libavcodec/bink.c
>>>>>> index 64a10b7..32330fe 100644
>>>>>
>>>>> [...]
>>>>>
>>>>>> +/**
>>>>>> + * Caclulate quantization tables for version b
>>>>>> + */
>>>>>> +static av_cold void binkb_calc_quant()
>>>>>> +{
>>>>>> + float s[64];
>>>>>> + int i, j;
>>>>>> +
>>>>>> + for (j = 0; j< 8; j++) {
>>>>>> + for (i = 0; i< 8; i++) {
>>>>>> + if (j&& j != 4)
>>>>>> + if (i&& i != 4)
>>>>>> + s[j*8 + i] = cos(j * M_PI/16.0f) * cos(i * M_PI/16.0f) * 2.0f;
>>>>>> + else
>>>>>> + s[j*8 + i] = cos(j * M_PI/16.0f) * sqrt(2.0f);
>>>>>> + else
>>>>>> + if (i&& i != 4)
>>>>>> + s[j*8 + i] = cos(i * M_PI/16.0f) * sqrt(2.0f);
>>>>>> + else
>>>>>> + s[j*8 + i] = 1.0f;
>>>>>> + }
>>>>>> + }
>>>>>> +
>>>>>> + for (j = 0; j< 16; j++) {
>>>>>> + for (i = 0; i< 64; i++) {
>>>>>> + binkb_intra_quant[j][i] = (1L<<12) * binkb_intra_seed[i] *
>>>>>> binkb_num[j]/(float)binkb_den[j] * s[i];
>>>>>> + binkb_inter_quant[j][i] = (1L<<12) * binkb_inter_seed[i] *
>>>>>> binkb_num[j]/(float)binkb_den[j] * s[i];
>>>>>> + }
>>>>>> + }
>>>>>> +}
>>>>>
>>>>> Can you run the following test:
>>>>>
>>>>>
>>>>> for (j = 0; j< 16; j++) {
>>>>> for (i = 0; i< 64; i++) {
>>>>> int x = ( 1 + (1<<20))/((float)(1<<20))) * (1L<<12) *
>>>>> binkb_intra_seed[i] * binkb_num[j]/(float)binkb_den[j] * s[i];
>>>>> int y = (-1 + (1<<20))/((float)(1<<20))) * (1L<<12) *
>>>>> binkb_intra_seed[i] * binkb_num[j]/(float)binkb_den[j] * s[i];
>>>>> if (i != y)
>>>>> av_log(NULL, "%d %d\n", i, j);
>>>>> }
>>>>> }
>>>>>
>>>>> and analogously for binkb_inter_quant? If there are any values that
>>>>> are not stable to fp rounding, it is enough to hardcode them...
>>>>
>>>> Hard coding the quant tables will add 8k to libavcodec. Anyway heres
>>>> the output:
>>>
>>> I was thinking more of hardcoding only the values that were printed,
>>> but I didn't expect them to be so many.
>>>
>>>> av_log(0,0, "intra\n");
>>>> for (j = 0; j< 16; j++) {
>>>> for (i = 0; i< 64; i++) {
>>>> int x = ( 1 + (1<<20))/((float)(1<<20)) * (1L<<12) *
>>>> binkb_intra_seed[i] * binkb_num[j]/(float)binkb_den[j] * s[i];
>>>> int y = (-1 + (1<<20))/((float)(1<<20)) * (1L<<12) *
>>>> binkb_intra_seed[i] * binkb_num[j]/(float)binkb_den[j] * s[i];
>>>> if (x != y)
>>>> av_log(0, 0, "%d %d\n", i, j);
>>>> }
>>>> }
>>>>
>>>> av_log(0,0, "inter\n");
>>>> for (j = 0; j< 16; j++) {
>>>> for (i = 0; i< 64; i++) {
>>>> int x = ( 1 + (1<<20))/((float)(1<<20)) * (1L<<12) *
>>>> binkb_inter_seed[i] * binkb_num[j]/(float)binkb_den[j] * s[i];
>>>> int y = (-1 + (1<<20))/((float)(1<<20)) * (1L<<12) *
>>>> binkb_inter_seed[i] * binkb_num[j]/(float)binkb_den[j] * s[i];
>>>> if (x != y)
>>>> av_log(0, 0, "%d %d\n", i, j);
>>>> }
>>>> }
>>>
>>> What if you use doubles and replace 1<<20 by 1<<48?
>>
>> There are less.
>>
>> intra
>> 0 0 (x:65536 y:65535)
>> 4 0 (x:65536 y:65535)
>> 32 0 (x:118784 y:118783)
>> 36 0 (x:151552 y:151551)
>> 0 3 (x:131072 y:131071)
>> 4 3 (x:131072 y:131071)
>> 32 3 (x:237568 y:237567)
>> 36 3 (x:303104 y:303103)
>
> Looks like the only problem is with i == 0, 4, 32 or 36, which is when
> s[i] == 1.0. Thus I propose the attached patches.

New version attached, with cosmetics included.

-Vitor