NAME¶
lav2wav - Extract the audio out of MJPEG container files to stdout
SYNOPSIS¶
lav2wav [
-s num] [
-c num] [
-v
num] [
-I] [
-R] [
-r samplerate,
bitesize, channels]
lavfile1 [lavfile2 ...
lavfileN]
DESCRIPTION¶
lav2wav can be used to extract the audio to stdout. This output goes to
stdout and can be saved as a wav file or piped to another sound processing
tool that is able to handle the wav format. This can be mp2enc and toolame for
mpeg layer 2 audio, or for example lame for mpeg layer 3 audio.
The input files may be any combination of AVI (.avi), Quicktime (.qt) or
editlist files so long as they are all lavtools- readable (e.g. MJPEG-encoded
AVI/Quicktime or DV type 2 AVI).
OPTIONS¶
lav2wav accepts the following options:
- -s num
- Start extracting at video frame (num)
- -c num
- Extract (num) frames of audio
- -v num
- Verbosity level (0, 1 or 2)
- -I
- Ignore unsupported bitrates/bits per sample
- -R
- If the file does not contain any sound. lav2wav will create silence with
44100kHz Sampelrate, 16 Bit audio bitsize and 2 Chanels
- -r sr,bs,ch
- If the file does not contain any sound lav2wav will generate silence with
the values you supply the samplerate (sr), audio-bitsize (bs) and channel
(ch).
BUGS¶
The "WAV" file format (technically: RIFF) is really very much less
than ideal for a tool intended to be used in pipelines as lav2wav is. The
problem is that the header includes a field specifying the length of the file.
This can't be filled in except by seeking back to the begining and
over-writing. If the output is unseekable (e.g. pipe) lav2wav simply writes a
large length into the header and leaves it at that. Most tools like
sox(1) or
mp2enc(1) either ignore the length field anyway or only give a warning.
The audio length is inacurate calculated when lav2wav generates silence. This
happens only if you have NTSC framerate and than it creates for every hour of
video 1.1498sec too less of silence.
AUTHOR¶
This man page was written by Bernhard Praschinger.
If you have questions, remarks, problems or you just want to contact the
developers, the main mailing list for the MJPEG-tools is:
mjpeg-users@lists.sourceforge.net
- For more info, see our website at
- http://mjpeg.sourceforge.net
SEE ALSO¶
mjpegtools(1),
mp2enc(1),
sox(1)