[Flac-dev] wav to flac corruption

[Brian Willoughby]

Matthew,

I don't think I can answer your entire question, but I will list a  
few pieces of information.

1) I regularly convert very large AIFF files, up to 4 GB, using  
flac.  I sometimes work with WAV, and that seems to work, too.  On my  
Mac, I can play flac files just fine in Play.app, VLC, and my own  
software.

2) What do you mean the flac "files do not work"?  You mean they  
don't play?  They will only play from software with full support for  
the flac format, which means many popular applications will not work.

3) I have not heard of "flac123" - perhaps this program is out of  
date or is missing support.  Maybe the author(s) of flac123 will  
comment.

4) Those warning mean that your Broadcast Wave File (BWF) is being  
converted to standard audio flac, without any of the metadata from  
the BWF.  You'll need to use --keep-foreign-metadata if there is any  
importance to having the original BWF restored later.  However, if  
all you need is the audio and none of the other information, then you  
can safely ignore these warnings.  FLAC always preserves all of the  
audio losslessly, you only ever have to worry about losing non-audio  
data.

5) You can only split a flac file if your splitting program  
understands the format.  You should learn the FLAC library and see  
what kind of support it has for breaking a stream.  If you use other  
tools to split the file without knowledge of the FLAC format, you  
will lose data.  In other words, you must develop a new program,  
maybe called "flacsplit," to do this, because wavsplit will not work  
on FLAC (unless they parse the FLAC format correctly as well as WAV).

I hope some of this information helps.

Brian Willoughby
Sound Consulting


On Feb 5, 2008, at 16:54, Matthew Davis wrote:
I'm attempting to convert fairly large WAV files (90 - 800 MB each)  
using flac but the files do not work after the encoding. (The play  
fine in wav format)

Command I'm using:

flac --verify -8 file.wav

Attempting to run the file with either flac123 or the default player  
for Ubuntu (Movie Player?) results in the extremely terse messages:
Default Player: "An Error Occurred: Could Not Decode Stream"
flac123: "error handler called!" <- repeated over and over and over

There are no errors during the encoding, though there are some  
warnings.  Here is the output:

asdarq at eighty-desktop:~$ flac -f -8 --verify 10_A.wav

10_A.wav: WARNING: skipping unknown sub-chunk 'bext' (use --keep- 
foreign-metadata to keep)
10_A.wav: WARNING: legacy WAVE file has format type 1 but bits-per- 
sample=24
10_A.wav: WARNING: skipping unknown sub-chunk 'minf' (use --keep- 
foreign-metadata to keep)
10_A.wav: WARNING: skipping unknown sub-chunk 'elm1' (use --keep- 
foreign-metadata to keep)
10_A.wav: 100% complete, ratio=0.62410_A.wav: WARNING: skipping  
unknown sub-chunk 'regn' (use --keep-foreign-metadata to keep)
10_A.wav: WARNING: skipping unknown sub-chunk 'ovwf' (use --keep- 
foreign-metadata to keep)
10_A.wav: WARNING: skipping unknown sub-chunk 'umid' (use --keep- 
foreign-metadata to keep)
10_A.wav: Verify OK, wrote 168060055 bytes, ratio=0.624


As a final random test, I attempted to split one of the wav files (my  
ultimate goal is split flac files) using wavsplit.  That resulted in  
the following output/error.

Channels: 1
Samplerate: 96000Hz
Samplebits: 24
Databytes: 269503836

Split         Hours  Mins   Seconds         Bytes         %
Bad file format