A little help understanding FIFOs?

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11-01-2005

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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 OPENDARWIN

ogginfo

ogginfo(1)							   Vorbis Tools 							ogginfo(1)

NAME

       ogginfo - gives information about Ogg files, and does extensive validity checking

SYNOPSIS

       ogginfo [ -q ] [ -v ] [ -h ] file1.ogg ...  fileN.ogg

DESCRIPTION

       ogginfo reads one or more Ogg files and prints information about stream contents (including chained and/or multiplexed streams) to standard
       output. It will detect (but not correct) a wide range of common defects, with many additional checks specifically for Ogg Vorbis streams.

       For all stream types ogginfo will print the filename being processed, the stream serial numbers, and various common error conditions.

       For Vorbis streams, information including the version used for encoding, the sample rate and number of channels, the bitrate  and  playback
       length, and the contents of the comment header are printed.

       Similarly,  for Theora streams, basic information about the video is provided, including frame rate, aspect ratio, bitrate, length, and the
       comment header.

OPTIONS

       -h     Show a help and usage message.

       -q     Quiet mode. This may be specified multiple times. Doing so once will remove the detailed informative  messages,  twice  will  remove
	      warnings as well.

       -v     Verbose mode. At the current time, this does not do anything.

AUTHORS

       Michael Smith <msmith@xiph.org>

SEE ALSO

       vorbiscomment(1), ogg123(1), oggdec(1), oggenc(1)

Xiph.Org Foundation						   July 10, 2002							ogginfo(1)