struct JxlChunkedFrameInputSource
{ ... };
const void* (*get_color_channel_data_at)(void*, size_t, size_t, size_t, size_t, size_t*)
const void* (*get_extra_channel_data_at)(void*, size_t, size_t, size_t, size_t, size_t, size_t*)
void (*release_buffer)(void*, const void*)