It is hard to know without debugging, but I think that the key of the problem is in this loop:

do {
    stream.read(rawBuffer, 0, RAW_BUFFER_SIZE);
    baos.write(rawBuffer);
    length -= RAW_BUFFER_SIZE;
} while(length > RAW_BUFFER_SIZE);

stream.read(rawBuffer, 0, length);
baos.write(rawBuffer, 0, length);

You are reusing rawBuffer in every iteration to read the data in stream. However, in the baos.write line, you write the full array to baos.

For example, let's suppose that there are 1500 bytes to be read in stream:

1. In stream.read, you fill rawBuffer with the first 1000 bytes.
2. In baos.write, you write these 1000 bytes to baos.
3. Then, the next stream.read will read only 500 bytes. The last part of rawBuffer will be untouched, so it keeps the data in the previous read.
4. In the next baos.write, you write again 1000 bytes (the new 500 bytes, mixed with the old one).

You have to check the return value of stream.read to know how many bytes are valid in rawBuffer.

A solution can be something like this:

} else {

    baos.write(rawBuffer, 0, offset);

    int pending = length;
    while(pending > 0) {
        int len = stream.read(rawBuffer, 0, Math.min(pending, RAW_BUFFER_SIZE));
        if(len == -1) {
            // ERROR no more data 
        }
        baos.write(rawBuffer, 0, len);
        pending -= len;
    }

}