5.1 FLAC decoding |
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5.1 FLAC decoding |
Mar 11 2009, 02:41
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#1
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Group: Members Posts: 3 Joined: 11-March 09 Member No.: 67826 |
I have received a FLAC file containing 5.1 audio data in six discrete channels.
FLAC Front-End successfully decodes this to a .wav file. WMP will not play either the FLAC original or the decoded .wav file. Winamp will play the .wav file - apparently in 2-channel stereo My old version of Cool Edit 2.1 will import the wav file as a multi-channel file and shows six separate waveforms when imported. In multichannel mode, I can play any one or several of these channels, but these are all panned by default as Centre and are labelled 1 to 6 with no indication which is which. It is of course very easy to tell which of the six channels is the LFE (or sub-woofer) track; surprisingly, this shows up as Channel 4 of 6 (I would have thought 6 of 6 would be normal). It is not so easy to tell which of the other five channels is which. I am not familiar with the material, but by listening carefully to the Winamp playing, I can more or less tell which is Left and which is Right, but I am not really sure which is front and rear and even less certain which is Centre channel. Is there a standard methodology for the channel arrangement? If not, what other detection methods work reliably. What I hope to do eventually is to upsample the bitrate and resolution to 96/24, edit the material in Cool Edit then encode and burn the six channels to DVD-A using Disc Welder. Any tips? |
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Mar 11 2009, 05:53
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#2
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FLAC Developer Group: Developer Posts: 1526 Joined: 27-February 02 Member No.: 1408 |
if the 4th channel is lfe, it's probably the standard 6ch assignment (fl, fr, fc, lfe, sl, sr)
see channel assignment: http://flac.sourceforge.net/format.html#frame_header if it has a WAVEFORMATEXTENSIBLE_CHANNEL_MASK tag you can figure it out from that |
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Mar 11 2009, 13:22
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#3
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Group: Members Posts: 3 Joined: 11-March 09 Member No.: 67826 |
Thanks Josh,
I guess I'll take it that the file is standard and work from there. Thanks for the link. I tried a couple of things to discover whether the file has the tag you mention and what it contains if it exists, but I don't know how to do this. I can't find any reference in the "explain" feature for FLAC and none of the references on a web search helps. Still, I am fairly confident I won't need to know. Presumably, if I want a 2-channel stereo mix of this, I pan the Left front channel 100% Left, pan the Right front channel Right and leave LFE in the centre. I am guessing I won't need the Centre channel as this is usually derived from LF and RF anyway. The rear channels are essentially echo from the front channels, so I would not want to try to mix those in at all. Is that Correct, Nearly correct, or Close enough for government work? Regards |
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Mar 12 2009, 05:45
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#4
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FLAC Developer Group: Developer Posts: 1526 Joined: 27-February 02 Member No.: 1408 |
you can use
CODE metaflac.exe --list --block-type=VORBIS_COMMENT to show all the tags, or just CODE metaflac.exe --show-tag=WAVEFORMATEXTENSIBLE_CHANNEL_MASK |
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Mar 12 2009, 14:58
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#5
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Group: Members Posts: 3 Joined: 11-March 09 Member No.: 67826 |
Thanks again, Josh.
As it happens, I think the WAVEFORMATEXTENSIBLE_CHANNEL_MASK tag is missing from the file. The only tag data types are Streaminfo, Vorbis_Comment and Padding and the only Vorbis tags are Length, Vendor string and (5) Comments containing text details of the recording. A Streaminfo tag confirms the data is 6-channel but that's it. Anyway DVD-R blanks are 35¢, so if it doesn't come out right I'll re-do it. Regards |
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Lo-Fi Version | Time is now: 25th May 2013 - 14:02 |