Libvmaf Feature request: List of built in models

[ThatNerdUKnow]

Hey I'm trying to write a rust wrapper library around libvmaf and I'm stuck on the implementation of VmafModel It seems that I can pass the name of the model into the "version" param of vmaf_model_load but there doesn't seem to be any variable or function I can use to get a list of valid strings that I can pass to this param. I can see that in model.c there seems to be a list of models that are imported alongisde their respective data in a variable called built_in_models which is an array of VmafBuiltInModel Neither VmafBuiltInModel nor built_in_models are exposed in the headers of the library, meaning that my bindgen script can't create definitions for them automatically. The alternative is that I would have to manually keep a list of what models that vmaf includes in my wrapper library which seems fragile

[ThatNerdUKnow]

Here's the list of built in models i'm referring to in libvmaf/src/model.c

static const VmafBuiltInModel built_in_models[] = {
#if VMAF_BUILT_IN_MODELS
#if VMAF_FLOAT_FEATURES
    {
        .version = "vmaf_float_v0.6.1",
        .data = &src_vmaf_float_v0_6_1_json,
        .data_len = &src_vmaf_float_v0_6_1_json_len,
    },
    {
        .version = "vmaf_float_b_v0.6.3",
        .data = &src_vmaf_float_b_v0_6_3_json,
        .data_len = &src_vmaf_float_b_v0_6_3_json_len,
    },
    {
        .version = "vmaf_float_v0.6.1neg",
        .data = &src_vmaf_float_v0_6_1neg_json,
        .data_len = &src_vmaf_float_v0_6_1neg_json_len,
    },
    {
        .version = "vmaf_float_4k_v0.6.1",
        .data = &src_vmaf_float_4k_v0_6_1_json,
        .data_len = &src_vmaf_float_4k_v0_6_1_json_len,
    },
#endif
    {
        .version = "vmaf_v0.6.1",
        .data = &src_vmaf_v0_6_1_json,
        .data_len = &src_vmaf_v0_6_1_json_len,
    },
    {
        .version = "vmaf_b_v0.6.3",
        .data = &src_vmaf_b_v0_6_3_json,
        .data_len = &src_vmaf_b_v0_6_3_json_len,
    },
    {
        .version = "vmaf_v0.6.1neg",
        .data = &src_vmaf_v0_6_1neg_json,
        .data_len = &src_vmaf_v0_6_1neg_json_len,
    },
    {
        .version = "vmaf_4k_v0.6.1",
        .data = &src_vmaf_4k_v0_6_1_json,
        .data_len = &src_vmaf_4k_v0_6_1_json_len,
    },
#endif
    { 0 }
};

You may not want to expose this struct directly, but a function that returns an array of strings containing the "version" field of these structs would be nice

[kylophone]

Yes, we would need to add a public API for that. I would be open to adding, I think it would be useful.

[ThatNerdUKnow]

Should I create a PR?

[kylophone]

Should I create a PR?

Yes, feel free to give it a shot. I would prefer an iterator function to scan through them. See this one from FFmpeg for inspiration: https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/codec_desc.h#L109-L116

[ThatNerdUKnow]

Cool, I'll give it a try

[ThatNerdUKnow]

Wrote an implementation based on avcodec_descriptor_next from avcodec.
23138fd
Any guidance on unit testing?

[ThatNerdUKnow]

@kylophone I took another crack at this in PR #1424
I've gotten more comfortable with programming in C and this implementation does not rely on the memory layout of VmafBuiltInModel