You asked earlier how large my FT WAV was; I can't remember but it's almost certainly the same size as the one you got with spdifconvert. LeeBorkman Wrote: > Hi again, I finally got a working copy of spdifconvert.py (downloaded > without problem at my office, but impossible at home). Ran it on Fight > Test and got a 47Meg WAV instead of the 170Meg WAV when I use Foobar2000 > to do the conversion. I then further converted that 47Meg WAV to a > 30Meg FLAC, just as in your example. Fantastic. Now I just have to > get this FLAC home and try it on my Squeezebox. > > Interesting for a 5.1 novice like me... the huge WAV and FLAC that > FoorBar2000 creates play as perfectly clear audio (only 2 channels > heard) in FB2k, and are identified as 6-channel content. The WAV/FLAC > created by the spdifconvert tool play as complete white noise, and > identify as 2-channel content only. So your spdifconvert tool is > decoding the 6 channels in the ac3, and re-encoding these into 2 > completely garbled WAV channels? Is that correct? Can you tell us if > this re-encoding is lossy or not? Am I getting the full meaty goodness > from my original AC3s?My tool isn't doing any decoding, actually. AC3 is > stored in a series of frames (relatively small chunks of data) throughout the .ac3 file. A DD5.1-aware receiver can understand the content of those frames, and will decode them to 6 discrete channels, but the trick is in getting the frames to the receiver in the first place.
The SB2 can send ordinary uncompressed PCM audio (like you'd find in a WAV file) to a receiver. There's a technical standard which describes how to use that format to contain non-PCM data; when the SB2 sends such a file to your receiver, which knows that technical standard, the receiver pulls the non-PCM data (in our case, AC3 or DTS) out of the file. My utility takes each AC3 frame and wraps it in a different type of frame. This stream of new frames is put into a WAV file so that when the SB2 plays it back as it would any other WAV file, it really ends up sending data to the receiver in the format we want. (It's like we're tricking the SB2 into sending data in our special format even though the SB2 doesn't know about that format; in fact, that standard I mentioned seems to exist for just this reason.) So I don't decode the AC3 data (into 6-channels of audio) at all, but simply tweak the format of the data so that the SB2/receiver will swallow it. As a result, the WAV contains compressed AC3 data which sounds like white noise when decoded as if it were normal sound. (But if you don't decode it, and just let your receiver decode it, the magic happens! Connect your soundcard to your amp with a digital connection, keep your Windows volume at maximum and fb2k volume at a 0.00dB adjustment, and these special WAV files will work. It's all a matter of getting the playback chain to send the special WAV files to the amp without modification.) My conversion process is lossless, and you should be hearing the full quality of your AC3 files. -- smst ------------------------------------------------------------------------ smst's Profile: http://forums.slimdevices.com/member.php?userid=752 View this thread: http://forums.slimdevices.com/showthread.php?t=19260 _______________________________________________ ripping mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/ripping
