Is the live tv buffer (ring buffer) per tuner or all of the tuners / size?

Or does it just use X gigabytes max, whoever uses up more first..?

it's one buffer.
the file is overwritten on any change of channel or change of tuner.

That was my initial thought too, but then I thought what if you have multiple frontends and have two or even three livetv's running a the same time, and I really don't know how it handles that.

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Xsecrets

The ringbuffer is local to the frontend.

So I suppose another way of thinking about it is one ringbuffer per frontend.

so how do you handle a network boot frontend, you have to create a seperate directory for it? or I suppose if you didn't then you would be creating multiple ring buffers in the same directory, and in the case of knoppmyth could easily blow out your partition.

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Xsecrets

Thats exactly my problem... I am using multiple front-ends to a single back end.

If the ring buffer is local to the local system, then fine. That will work.

To answer your question xsecrets, I'm sure you need to mount a network drive for a network-boot machine and write to there.

Honestly, I think its bad design to have the ring buffer be in a seperate partition. It should sit along with all your other files. The reason? Three fold:

1. "Just Because", because your system has to fully support writing to that partition by N-number of tuners ANYWAYS, and in doing so, fully support pause, ffwd etc anyways. There is no reason to flip off the main partition and do it somewhere else for "performance" reasons. If your system can't do it to the main partition, it won't be able to do it to a secondary one.

2. If you write your ringbuffer to the same partition as your recordings, you can do a real-time file-rename to the show name and continue recording when the user selects to record a show that has some data in the ring buffer. TIVO does this wonderfully, there is no reason that I can think of that MythTV shouldn't be able to do this as well.

3. Your example: If you have a front end thats booting off of anything that doesn't have much HD space, or very slow storage (flash e.g), or ZERO HD space... Again, if the server can record n-tuners at the same time on the back end, and stream over, it can sure the heck record onto the same local partition for Live-TV and stream that over.


Honestly though, maybe there is a reason for it all. I just don't see it.

well initially I think the reason was two fold if for some reason (it happens sometimes) the ringbuffer doesn't delete properly it only fills up the cache partition, and second probably the biggest reason was initially knoppmyth cache partion was heavily optimized for large files, with greatly reduced inodes, and you don't want that on your main partition. the myth partition is already bad enough about this as many people with thousands of roms or mp3's have found out.

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Xsecrets

Does this mean that if you run a diskless frontend, using live TV with the ringbuffer on a network share that the video data is transferred over the network to the frontend, written back over the network to the backend again and then read from the backend again for playback?

That sounds crazy. But I guess it would not be usual to have the ring buffer on a network share.

the cache file takes a single Inode...

A ring buffer not getting deleted is simply a bug, fix it. Seriously.

File systems like XFS are a good thing(tm).

I think MythTV needs to change now, and even though I am "all talk" right now, I am seriously thinking about "fixing it" myself. (and sharing my changes back with the public of course).

Then file a bug report with the MythTV devs... Several folks have stopped by the forum and flapped thier soup coolers talking about helping out. Action my friend, action.

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cesman

When the source is open, the possibilities are endless!

not my style. I don't go on dev forums and file for big things like this, I'll just do it myself.

What is stopping you from pointing the cache at a directory in the /myth partition?

It seems to me that the decision to put the cache on a separate partition is more a KnoppMyth thing than a mythtv thing.

Having said that if what you are proposing is to change mythtv so that the livetv buffer can be renamed and made into a recording whilst you are wating it, then I guess that has some merit. Isnt the fact that it is a *ringbuffer* instead of a standard file going to cause you grief though (if the buffer has filled and started writing at the start again)?

You are correct sir.

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cesman

When the source is open, the possibilities are endless!

BTW - A thought occured to me... You've got to be able to have multiple live TV buffers files if you're going to do PIP, and since my recollection is that the file name has a number appended to it, I suspest that there is support for more than one.