forMultistreamChunkSize
s = MediaString::forMultistreamChunkSize(format.u.multistream.avg_chunk_size,
s = MediaString::forMultistreamChunkSize(format.u.multistream.avg_chunk_size,
s << (empty ? "" : ", ") << forMultistreamChunkSize(format.avg_chunk_size,
static BString forMultistreamChunkSize(