There’s a 2013 Audi Allroad 2.0T in the Motor Trend Garage, signed out to Arthur St. Antoine, and his update in the November issue contains this observation:
I giddily loaded up a memory card with lossless audio files (using both FLAC and ALAC codecs), only to discover that the head unit won’t play files with bit rates higher than 320 kbps.
I stared at this, realized I didn’t know what difference bit rates made in FLAC in the first place, and duly hunted down the FAQ:
With FLAC you do not specify a bitrate like with some lossy codecs. It’s more like specifying a quality with Vorbis or MPC, except with FLAC the quality is always “lossless” and the resulting bitrate is roughly proportional to the amount of information in the original signal. You cannot control the bitrate much and the result can be from around 100% of the input rate (if you are encoding noise), down to almost 0 (encoding silence).
So I went to my small folder of FLAC files and played them through Winamp, which has a semi-reliable bit-rate indicator. The absolute lowest bit rate obtained was 807 kbps.
Curious, I pulled out a wav file from the archives and shot it through the FLAC frontend at the default “quality level” of 6. It came back at 910 kbps.
So instead of sniping at St. Antoine for being picky, I get to grouse at Audi for failing to anticipate this sort of thing.