Update on my conversion utility: I've written a Python script which can convert an AC3 file to a WAV file suitable for streaming to an SB2. My recommendation is still that an AC3 file is pre-converted to WAV, and then to FLAC so that metadata can be set. However, my utility does estimate the output WAV file length (correctly, in my tests so far) so it should be easy enough to use at run-time (haven't tried this yet... I don't know if the Python script will just work if it's in the right binary directory).
I do need to implement some sort of burst/padding special case that I don't quite understand from the specs yet. :) Next to do is DTS conversion. I believe I just need to (1) parse enough DTS to get the frame size (and then read the frame), and (2) write out the correct preamble (it's different from AC3). There are software DVD players out there which already play DTS streams, so I should be able to take some cues from that. The problem with pre-converted files is that they're just WAV/FLAC. Although they play just fine on the SB2, they won't work in, say, foobar2000, or (probably) WinAmp. I'd like to make a recommendation about how to alleviate confusion with such files, but I'd like other people's views too. I see two choices: 1. Leave the file names as "whatever.ac3.flac" (or "whatever.dts.flac"). Humans can see the embedded file type, but WinAmp/fb2k/etc will have problems playing them. SB2 will just work with a digital output, but won't work with analogue outputs (and it can't tell the difference between normal FLACs/WAVs and these special FLACs/WAVs for the analogue output). 2. Use a custom extension for converted files, say "whatever.ac3.spdif-wav" and "whatever.ac3.spdif-flac". (And "whatever.dts.spdif-wav", etc.) No danger of other software thinking, because of the file name, that the file is understandable audio. The 'spdif' and 'spdif-flac' extensions are of course open for debate. Question for those in the know: can 'convert.conf' be configured to do something different depending on whether the player is using digital outputs? In particular, we'd probably want to convert the audio to silence for players that can't take it (or possibly get more complex and find some utility to decode the file and downmix it!). Question about SB1: what's the situation with digital pass-through? I believe there's a firmware bug which causes the data to be corrupted in some way (bit inversion? Byte swapping?). That would affect these converted files; I guess it would also affect a standard WAV. Is that right? A utility to convert the digital files to an SB1-compensating format would be useful (and not too tricky, I think), but does it need to be applied to all WAV files or just those with the proposed special extension? I welcome any ideas or answers. -- smst _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
