pipe device/utility + buffer size & discard - ffmpeg mplayer

[paziu]

I am looking for a device or an utility that works similar to the FIFO, but has a specified buffer size - let say 10 MiB - and starts discarding oldest it received.
It would behave like a "pipe" that has 10m in length - but keeps only & always 10m * π r2 of water,

I would use if for feeding a live audio/video stream, which encodes all the time - and attach a player any given time - it would fill its buffer quickly, and start playing.
This way, it would be possible to use different applications, that "specialize" in certain features:
1> audio/video grabber
2> a/v encoder
3> a/v server
4> a/v player

projects such as ffmpeg, which can do "most of this all" but have certain limitations and/or unexpected behavior.
so it would be possible to use mencoder's capturing ( from what I see they are a bit better: forceaudio & immediatemode options ) to the "10 meter" pipe "buffer" and server which would be ffserver ( ffmpeg )

I am sure there would be other uses such as PVR with rewind as long as the length of the "pipe".... or pre-buffering next title in the playlist for a smooth playback start...

basically a fifo without the requirement of the "receiver" and with a specified buffer size
or something like
<pre or post process a/v stream> | fifo_buffer | mplayer -
or
an utility that creates a "temp" file that never exceeds specified "buffer" size, and discards the oldest data in order to accept new.

is there something like this already available?

Thanks,

Mike

[eccerr0r]

Theoretically vlc (videolan server) should do this before it became an all-inclusive media player. The original VLC project was to build a streaming cross platform video server, using the LAN as the "video wire" much like what s-video cable does, so to speak.

Granted I have not tried to use this before... just theory...
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[paziu]

Thank you for your reply and suggestion, I will look also into the server, as long as it can run in a shell / service

In the meantime I was hunting for an utility that could provide me with a similar functionality - I found mbuffer / buffer - both are able to receive an specified amount of data, "keep" it, fill, and release, but there is no option to discard the oldest data within the buffer space.
I already said this sentence ( many times ): I wish I would be able to write/modify in ansi/gnu c...
I believe there would be a number of cases such "buffered pipe" could be used:

- receiving multiple A/V streams, and change between them instantly, without any "resolving, connecting to... buffering" time - like switching channels on the TV.
- also good for playlists, with pre-buffering of the "next in the list" entry
- maybe even a kind of PVR/ time lapse - switch to a different "channel" instantly and rewind up to N minutes since all streams are already pre-buffered <--- you can not get it on basically any consumer device available
- for larger networks, pre-buffer 10....20....100 streams and let the users connect to let say ffserver, with near instant delivery of the content, and potential large bandwidth savings.

and all I want to do right now, is pre-buffer 20 seconds of a captured analog signal ( A/V ) to feed an encoder at home....

Thanks again!

Mike


EDIT:

I have been looking too far out... there is "bfr" in app-misc
"General-purpose command-line pipe buffer"

( found it on freshmeat )

this is what I was looking for, now the time came to see if I have been looking for the right thing....

now I can buffer the captured audio and video separatly, mux/encode it and hope for the right synchronization

EDIT2:

"bfr" along with the standard FIFO might prevent any buffer underruns... ( broken pipes? )

[eccerr0r]

I figure that buffering is an necessary evil with network viewing, because networks tend to hiccup causing frame drops...

Don't mind these URLs, I was just making a note for myself, as I was thinking about doing something like this as a security camera (so I can view what's going on in my house remotely, in real time)

http://serverfault.com/questions/288137/how-to-stream-live-video-from-a-linux-server

http://wiki.videolan.org/Stream_VLC_to_Website_with_asf_and_Flash

Someday...when I get a decent camera...
_________________
Intel Core i7 2700K/Radeon R7 250/24GB DDR3/256GB SSD
What am I supposed watching?