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A little help understanding FIFOs?

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Operating Systems Linux A little help understanding FIFOs?
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Old 11-01-2005
A little help understanding FIFOs?
This isn't strictly a Linux question, but... I've been working on a project to archive some streaming media for time shifting using 'mplayer' and have been using FIFOs to archive in Ogg Vorbis format:


Code:
mkfifo program_name.wav

(mplayer -ao pcm -aofile program_name.wav &)
MPLAYER_PID="`/sbin/pidof mplayer`"

(oggenc program_name.wav &)
OGGENC_PID="`/sbin/pidof oggenc`"

sleep 30m && kill -9 "$MPLAYER_PID" "$OGGENC_PID"
rm program_name.wav

That works OK. But some of the streams I archive are long (3-4 hours) and are difficult to "fast forward" through on my car player. So I'd like to break the recordings up into 5 minute segments WHILE I am encoding the stream. The problem is that when oggenc stops reading from the program_name.wav FIFO, mplayer stops streaming and won't start up again. Any ideas how I would do this without just grabbing the whole show in WAV format and then splitting it after the fact?
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LEARN ABOUT DEBIAN

oggz-merge

oggz-merge(1)						      General Commands Manual						     oggz-merge(1)

NAME

       oggz-merge -- Merge Ogg files together, interleaving pages in order of presentation time.

SYNOPSIS

       oggz-merge [-o filename	| --output filename ] filename ...

       oggz-merge [-h  | --help ]  [-v	| --version ]

Description
       oggz-merge  merges Ogg files together, interleaving pages in order of presentation time.  It correctly interprets the granulepos timestamps
       of Ogg CELT, CMML, Dirac, FLAC, Kate, PCM, Speex, Theora and Vorbis bitstreams.	Run oggz-known-codecs(1) for a full list of  codecs  known
       by the installed version of oggz.

       For  example,  if you have an Ogg Theora video file, and its soundtrack stored separately as an Ogg Speex audio file, and you can use oggz-
       merge to create a single Ogg file containing the video and audio, interleaved together in parallel.

       Similarly, using oggz-merge on a collection of Ogg Vorbis audio files will create a big Ogg file with all the songs in parallel, ie. inter-
       leaved for simultaneous playback. Such a file is proper Ogg, but not "Ogg Vorbis I" -- the Ogg Vorbis I specification defines an Ogg Vorbis
       file as an Ogg file containing only one Vorbis track at a time (ie. no parallel multiplexing). Many music players (which use libvorbisfile)
       aren't  designed  to  play  multitrack  Ogg  files.   In general however, video players, and anything built on a multimedia framework (like
       GStreamer, DirectShow etc.) will probably be able to handle such files.

       If you want to create a file containing some Ogg files sequenced one after another, then you should simply concatenate them together  using
       cat.  In  Ogg  this is called "chaining". If you cat Ogg Vorbis I audio files together, then the result will also be a compliant Ogg Vorbis
       file.

Options
       oggz-merge accepts the following options:

   Miscellaneous options
       -o filename, --output filename
		 Write output to the specified filename instead of printing it to standard output.

       -h, --help
		 Display usage information and exit.

       -v, --version
		 Output version information and exit.

EXAMPLES

       Merge pages of audio.oga and video.ogv:

	      oggz merge -o output.ogv audio.oga video.ogv

AUTHOR

       Conrad Parker	    September 21, 2004;

COPYRIGHT

       Copyright (C) 2004 CSIRO Australia

SEE ALSO

       cat(1), oggz-rip(1), oggz-dump(1), oggz-diff(1), hogg(1)

																     oggz-merge(1)