Streaming decompression of data in a vector

Question

I need to do the following procedure.

• Compress an input text into an array.
• Split the compressed output into multiple pieces with approx. the same length and store them in a vector.
• Decompress using streaming decompression.

Is it possible to do that? Consider that in my case, the size of each block is fixed and independent of the compression scheme.

In this example here, the decompression function returns the size of the next block, I wonder if that is somewhat related to the compression scheme, i.e. you cannot randomly take a sub-array contained in the full compressed array and decompress it.

I need to use zstd, no other compression algorithms.

Here is what I tried so far.

//std::vector<std::string_view> _content_compressed passed as parameter
ZSTD_DStream* const dstream = ZSTD_createDStream();
ZSTD_initDStream(dstream);
std::vector<char*> vec;
for (auto el : _content_compressed)
    {
        auto ee = el.data();
        char* decompressed = new char[1000];
        ZSTD_inBuffer input = { el.data(), el.size(), 0 };
        ZSTD_outBuffer output = { decompressed, _decompressed_size, 0 };
        std::size_t toRead = ZSTD_decompressStream(dstream, &output, &input);
        vec.push_back(decompressed);
}

The problem is that decompressed doesn't contain the decompressed value at the end.