[mythtv] running encoder in realtime

Daniel Kristjansson danielk at cuymedia.net
Tue Jan 17 15:52:17 UTC 2006

On Tue, 2006-01-17 at 10:24 -0500, Isaac Richards wrote:
> On Tuesday 17 January 2006 09:02, Daniel Kristjansson wrote:
> mpegrecorder really shouldn't need one, since it's not really doing much 
> parsing of the stream - it's passing off to the RingBuffer class quickly.  
> The ringbuffer has its own level of buffering for the disk output (in 
> ThreadedFileWriter), so you could probably get the same effect by just 
> increasing that buffer size.

MpegRecorder can choke on data before it gets buffered by
ThreadedFileWriter if it has problems writing the key-frame
map to the database. This can happen if the DB is on the
same disk as the MythTV video store. This is usually not a
problem for two or three ivtv cards unless you don't have
hard disk DMA transfers enabled, also have HDTV cards
installed and streaming to disk, or perform a huge file
transfer outside of MythTV.

That reminds me of a couple problems Tony might want to look at...
 1/ If you have the popular Via brand SATA chipset, it has a bug that
    requires a one second timeout on writes which causes problems for
 2/ Also make sure you use XFS or JFS as your file system for the video
    store, other file systems tend to deal badly with streaming data.
    Brandon Beattie had serious streaming problems that were greatly
    reduced by changing from RieserFS3 to XFS.

-- Daniel

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