[FFmpeg-devel] [PATCH v2 1/3] avfilter: add v360 filter

[Eugene]

On 14.08.2019 13:06, Paul B Mahol wrote:

> On Wed, Aug 14, 2019 at 11:56 AM Thilo Borgmann <thilo.borgmann at mail.de>
> wrote:
>
>> [...]
>>
>>>>> +static int config_output(AVFilterLink *outlink)
>>>>> +{
>>>>> +    AVFilterContext *ctx = outlink->src;
>>>>> +    AVFilterLink *inlink = ctx->inputs[0];
>>>>> +    V360Context *s = ctx->priv;
>>>>> +    const AVPixFmtDescriptor *desc =
>>>>> av_pix_fmt_desc_get(inlink->format);
>>>>> +    const int depth = desc->comp[0].depth;
>>>>> +    float remap_data_size = 0.f;
>>>>> +    int sizeof_remap;
>>>>> +    int err;
>>>>> +    int p, h, w;
>>>>> +    float hf, wf;
>>>>> +    float mirror_modifier[3];
>>>>> +    void (*in_transform)(const V360Context *s,
>>>>> +                         const float *vec, int width, int height,
>>>>> +                         uint16_t us[4][4], uint16_t vs[4][4], float
>>>>> *du, float *dv);
>>>>> +    void (*out_transform)(const V360Context *s,
>>>>> +                          int i, int j, int width, int height,
>>>>> +                          float *vec);
>>>>> +    void (*calculate_kernel)(float du, float dv, int shift, const
>>>> XYRemap4
>>>>> *r_tmp, void *r);
>>>>> +    float rot_mat[3][3];
>>>>> +
>>>>> +    switch (s->interp) {
>>>>> +    case NEAREST:
>>>>> +        calculate_kernel = nearest_kernel;
>>>>> +        s->remap_slice = depth <= 8 ? remap1_8bit_slice :
>>>>> remap1_16bit_slice;
>>>>> +        sizeof_remap = sizeof(XYRemap1);
>>>>> +        break;
>>>>> +    case BILINEAR:
>>>>> +        calculate_kernel = bilinear_kernel;
>>>>> +        s->remap_slice = depth <= 8 ? remap2_8bit_slice :
>>>>> remap2_16bit_slice;
>>>>> +        sizeof_remap = sizeof(XYRemap2);
>>>>> +        break;
>>>>> +    case BICUBIC:
>>>>> +        calculate_kernel = bicubic_kernel;
>>>>> +        s->remap_slice = depth <= 8 ? remap4_8bit_slice :
>>>>> remap4_16bit_slice;
>>>>> +        sizeof_remap = sizeof(XYRemap4);
>>>>> +        break;
>>>>> +    case LANCZOS:
>>>>> +        calculate_kernel = lanczos_kernel;
>>>>> +        s->remap_slice = depth <= 8 ? remap4_8bit_slice :
>>>>> remap4_16bit_slice;
>>>>> +        sizeof_remap = sizeof(XYRemap4);
>>>>> +        break;
>>>>> +    }
>>>>> +
>>>>> +    switch (s->in) {
>>>>> +    case EQUIRECTANGULAR:
>>>>> +        in_transform = xyz_to_equirect;
>>>>> +        err = 0;
>>>>> +        wf = inlink->w;
>>>>> +        hf = inlink->h;
>>>>> +        break;
>>>>> +    case CUBEMAP_3_2:
>>>>> +        in_transform = xyz_to_cube3x2;
>>>>> +        err = prepare_cube_in(ctx);
>>>>> +        wf = inlink->w / 3.f * 4.f;
>>>>> +        hf = inlink->h;
>>>>> +        break;
>>>>> +    case CUBEMAP_6_1:
>>>>> +        in_transform = xyz_to_cube6x1;
>>>>> +        err = prepare_cube_in(ctx);
>>>>> +        wf = inlink->w / 3.f * 2.f;
>>>>> +        hf = inlink->h * 2.f;
>>>>> +        break;
>>>>> +    case EQUIANGULAR:
>>>>> +        in_transform = xyz_to_eac;
>>>>> +        err = prepare_eac_in(ctx);
>>>>> +        wf = inlink->w;
>>>>> +        hf = inlink->h / 9.f * 8.f;
>>>>> +        break;
>>>>> +    case FLAT:
>>>>> +        av_log(ctx, AV_LOG_ERROR, "Flat format is not accepted as
>>>>> input.\n");
>>>>> +        return AVERROR(EINVAL);
>>>>> +    }
>>>>> +
>>>>> +    if (err != 0) {
>>>>> +        return err;
>>>>> +    }
>>>>> +
>>>>> +    switch (s->out) {
>>>>> +    case EQUIRECTANGULAR:
>>>>> +        out_transform = equirect_to_xyz;
>>>>> +        err = 0;
>>>>> +        w = roundf(wf);
>>>>> +        h = roundf(hf);
>>>>> +        break;
>>>>> +    case CUBEMAP_3_2:
>>>>> +        out_transform = cube3x2_to_xyz;
>>>>> +        err = prepare_cube_out(ctx);
>>>>> +        w = roundf(wf / 4.f * 3.f);
>>>>> +        h = roundf(hf);
>>>>> +        break;
>>>>> +    case CUBEMAP_6_1:
>>>>> +        out_transform = cube6x1_to_xyz;
>>>>> +        err = prepare_cube_out(ctx);
>>>>> +        w = roundf(wf / 2.f * 3.f);
>>>>> +        h = roundf(hf / 2.f);
>>>>> +        break;
>>>>> +    case EQUIANGULAR:
>>>>> +        out_transform = eac_to_xyz;
>>>>> +        err = prepare_eac_out(ctx);
>>>>> +        w = roundf(wf);
>>>>> +        h = roundf(hf / 8.f * 9.f);
>>>>> +        break;
>>>>> +    case FLAT:
>>>>> +        out_transform = flat_to_xyz;
>>>>> +        err = prepare_flat_out(ctx);
>>>>> +        w = roundf(wf * s->flat_range[0] / s->flat_range[1] / 2.f);
>>>>> +        h = roundf(hf);
>>>>> +        break;
>>>>> +    }
>>>>> +
>>>>> +    if (err != 0) {
>>>>> +        return err;
>>>>> +    }
>>>>> +
>>>>> +    if (s->width > 0 && s->height > 0) {
>>>>> +        w = s->width;
>>>>> +        h = s->height;
>>>>> +    }
>>>> If s->width/height are checked, should handle the case of no ture,
>>>> Else w/h may be used but not initialized.
>>>>
>>> Please try more hard to write english. I do not understand what is typed
>>> above.
>> If w and h don't have initial values at declaration. So they might never
>> get set if that last if statement evaluates to false.
>>
>> So he suggests to add an else case like
>>
>> if (s->width > 0 && s->height > 0) {
>>   w = s->width;
>>   h = s->height;
>> } else {
>>   w = 0;
>>   h = 0;
>> }
>>
>> or whatever values might make sense.
>>
> else case should have assert or return AVERROR_BUG.

This "if" branch overrides default values with user values. Default 
values are calculated just above this code based on input/output formats.
So w and h do get initialized in any case.

>
>
>> Thilo
>>
>>
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