bfr, bfp - nonblocking 8-bit-clean pipe buffer

bfr [-v[v]] [-t0] [-T0] [-b100] [-p<arg>] [-m0] [-T90] [-C0] [<input file or -> ...]

bfp [-v[v]] [-t0] [-T0] [-b100] [-p<arg>] [-m0] [-T90] [-s44100] [-S[y|n]] [-c2] [-B2] [-C0] [<input file or -> ...]

[see OPTIONS for the --long equivelants to these]

bfr's purpose is to buffer data. (I hope this is obvious. =)) It buffers from its standard input and/or a list of files of your choosing, and allows this data to flow to its standard output at whatever rate that end can handle. Its useful for any situation in which its beneficial to have I/O occur in a detached yet smooth fashion... possible applications:

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- CD burning. A user in Spain was using this in front of cdrecord, apparently the CPU couldn't keep up with the 8x burner, so 30 megs (cdrecord's limit) wasn't enough.

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- Backups. bfr can be configured to release its data in large chunks, rather than small flowing increments, which reduces tape seek. bfr also has a speedcap option, which ensures bfr will never output more than a certain amount (which you specify) of data per second. This makes it useful for network backups without saturating your backbone or T1.

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- Multimedia. Since bfr does its best to yield data to its output at whatever pace the other side can handle (essentially keeping the output stuffed full), it reduces skips. This helps both movies (the pr0n must go on!) and audio (ditto mp3!). The bfp program, included in this package, is an extension to bfr whose primary purpose is to aid skipless audio playback, by properly configuring and writing to /dev/dsp.

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-h | --help

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display a (hopefully) helpful message.

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-v | --verbose

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enable verbosity (use twice for pedantic verbosity)

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-p | --progress (*)

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Enables progress mode, with an optional arg specifying how to display the data. The optional arg should take the form of a letter and another part... the letter being k, b, m or p, specifying whether bfr filledness should be displayed in Kilobytes, bytes, megabytes or as a percentage. The second, if a number, should be the multiplier by which throughput is measured. Otherwise, it may be CD for CD data (150K/sec) or CA for CD audio (176K/sec). If either is omitted, they default is kilobytes and 1k, respectively. Typical values: k1k, to monitor data at the kilobyte level, and pCD and pCA to show meaningful values for CD data and CD audio (and total buffer usage as a percentage) , respectively. The default is k1k for bfr, pCA for bfp.

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-m | --minimum (*)

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Set the amount of buffer to reach before output begins (to ensure a full stream even at start). The default is 10%.

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-i | --initial (*)

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Initial is a special case of --minimum, which takes effect only for initial prebuffering before output starts the first time. If unspecified, it defaults to whatever --minimum is set to.

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-t | --timeout (*)

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Time, in seconds, to wait before aborting if both input and output are locked. A value of 0 means it will wait forever. The default is 0.

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-T | --throttle (*)

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After filling the buffer, bfr will allow the level of onhand data to go down to this amount before accepting more input. The default is 98%.

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-b | --buffersize (*)

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Full size of memory buffer. The default is 5m.

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-C | --speedcap (*)

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If set to a non-zero value, bfr will allow only this many bytes to be output per second.

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-s | --speed

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Sound samples per second. The default is 44100.

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-S | --signed

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Is the sound data signed (y) or unsigned (n)? The default is y.

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-c | --channels

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Number of channels (1 = mono, 2 = stereo). The default is 2.

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-B | --bytes

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Bytes per sound sample (1=8bit, 2=16bit). The default is 2 (16bit).

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-d | --debug

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enable debugging - only valid for the bfrdebug and bfpdebug executables, not built or in dist packages by default.

Options marked with a (*) can take their argument in simpler notation: You can use letters 'k' and 'm' can be used to specify kilobytes and megabytes. Decimals are not allowed, use '6500k' instead of '6.5M'. '1k' means 1024, and '1m' means 1048576. '80%' means, literally, 80 percent of buffersize. Percentages are mostly useful for the various threshold settings - using it with --buffersize or --timeout is a bit silly.

Full list of qualifiers:

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t - 1000 (1 thousand)

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K or k - 1024 (1 kilobyte)

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M - 1000000 (1 million)

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m - 1048576 (1 megabyte)

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b - 1000000000 (1 billion (either you're insane, or I want your hardware))

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G or g - 1073741824 (1 gigabyte (either you're insane, or I want your hardware))

If you find an inconsistency, whether its an unexpected or undocumented feature or something missing, please let me know!

First of all, thank you for using it. =)

Thanks also to the various people who have helped me at various stages of the way, through ideas, notes, suggestions, bugfixes and death threats, including but not limited to: miponme, Samuli Karkkainen, Scott Gifford, Sam Phillips, Andreas Metzler, Arnd Bergmann, Rob Ekl

Mark Glines <mark@glines.org>

http://www.glines.org/software/bfr.html

bag, dog