smst Wrote: > 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.
SB1 has bit-correct output at S/PDIF output except for a sign reversal of the samples. I get correct passthrough of DTS wav file if the sign of the samples is inverted. Steinar -- sbjaerum _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
