[mythtv] PCHDTV + DVB Integration / DTVRecorder RingBuffer Reversion Request

Daniel Thor Kristjansson danielk at mrl.nyu.edu
Mon Jan 3 09:49:07 EST 2005

On Sun, 2 Jan 2005, Taylor Jacob wrote:
]The most recent patches to dtvrecorder.cpp contain John Poets 
]ringbuffer that is necessary only for the PCHDTV and serves no purpose 
]for linux-dvb supported cards.. The ringbuffer also hangs the backend 
]with my dvb-patch code.. This has been reported by more than 1 person.. 
]Can this be backed out of dtvrecorder and placed where it belongs in 

I'm sure John added the new Ringbuffer code to DTVRecorder because he 
thought this could help DVB recording. 

]The concept behind my dvb patchset is to create a database heiarachy 
]that is representative of ANY digital television / radio service.. The 
]database used by the PCHDTV is not anything like this, and has resulted 
]in code like the DD Virtual Channel Number patches that I don't feel 
]are a proper way to go about things.. Recording of multiple channels 
]running on the same mux is quite difficult down the road with a 
]database that is built around analog tv.. This also complicates getting 
]guide data over the air which for ATSC will be mandated in 6 months 
]when the broadcast flag kicks in since that is where it is present at..  
]This DD patch also renumbers all of the channel numbers for the Air2PC 
]card if you attempt to use it with DD currently which is not necessary 

HDTVRecorder wouldn't be too difficult to use in recording multiple 
streams from the same channel. This is intentional. What is needed 
mostly is a scheduler that is aware of multiple 'channels' that can be 
recorded at once, and that cards can record either ATSC or NTSC at 
any one time, but not both. As soon as your DVB patches get applied to 
the MythTV CVS we will begin integrating the DVB and ATSC database 
schema, esp if this means the scheduler can take better advantage of the 

]Secondly the PCHDTV card ought to use the database structure that I 
]have setup for the linux-dvb cards which works properly with ATSC as 
]well as DVB in harmony.. I also have a service table updating class 
]that constantly monitors all of the SI (DVB) or PSIP (ATSC) tables and 
]keeps all the tuning information up to date..  This also helps reduce 
]the number of "bad channel hangs" that are common to both the DVB 
]codebase and HDTV codebase..

Why not publish the schema on this list, so we can debate it, and then 
submit a set of patches? I've been holding off on changing the schema 
for HDTV because I knew your stuff was in the pipeline.

]I feel right now the two groups (PCHDTV and DVB) are going in seperate 
]directions.. We need to be more organized if we are going to integrate 
]this code properly.. I know it is more difficult to deal with the 
]dvb-patch since it is not in myth-cvs now but if any of you PCHDTV 
]developers would like read access to the cvs that houses the dvb-patch 
]please let me know and I will be glad to provide this to you so we can 
]move twoard integration..

I really don't think we are going in different directions, the patches 
you've been seeing for ATSC have been in the pipeline for a long time. 
Someone submitted a workalike patch to John's while he was working on 
it. The last ATSC patch I submitted was a DVB integration patch. Since 
then the patches I've sent were all cleanup patches that I'd been 
working on for a while. I have a few more of those to finish, but then 
I'm planning on looking at your service table updating class. I have 
some requirements for this I would like, such as letting it work well 
with information from other sources, and letting the user disable or 
enable it on a channel by channel basis.

-- Daniel

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