Problems with international characters in metadata

Created by: jfhs

I've built PyAV for python 3, and it works fine, except that it fails on reading metadata from files, if they contain unicode/international (I'm not sure) characters. I.e. I had file with title for audio channel with russian letters, and got exception:

"UnicodeDecodeError: 'ascii' codec can't decode byte 0xd0 in position 0: ordinal not in range(128)"

I fixed that by changing the avdict_to_dict so that it returns bytebuffers instead of strings as values:

cdef dict avdict_to_dict(lib.AVDictionary *input):

    cdef lib.AVDictionaryEntry *element = NULL
    cdef dict output = {}
    cdef bytes value
    while True:
        element = lib.av_dict_get(input, "", element, lib.AV_DICT_IGNORE_SUFFIX)
        if element == NULL:
            break
        value = element.value
        output[element.key] = value
    return output

Maybe you'll find some other, more nicer way, but I'm not sure if there is a way to determine right encoding.