Blammo, How about questions related to HDTV setup in mythtv?
- How are HDTV channels set up? Using zap2it and an HDTV lineup resulted in a mix of NTSC and ATSC channels with incorrect freqid for the digital channels (e.g., in Chicago, Channel 7 (ABC) is actually broadcasting on 52). How is this set up via mythtv? - How are HDTV subchannels set up? Again, based on above, ABC is multicasting on 52. In mythtv, are the channels specified as freqid 52-1, 52-2? or some other format? How should these multi-channels be set up for names (mythtv channel input won't allow '.' (7.1, 7.2, etc.) or '-' (7-1, 7-2). Do these channels need to be renumbered (e.g., 900, 901)? For me, I cannot seem to get any other subchannel other than the first regardless of what I put in the freqid field in mythweb (using an HD-3000). - Based on http://thegeorges.us/mythtv instructions, the mythconverg database needs to be tweaked to set channel format to ATSC (assuming a default of NTSC). Is this necessary? What are the correct commands for setting this up? - If your mythtv setup receives OTA NTSC and ATSC, is there any reason to keep the NTSC channels within mythtv? If so, how should these be set up (similar issues as above since you now have two (or more) channel 7's)? Is there a priority scheme within mythtv to make sure it records a show off the ATSC stream before choosing the same show on the NTSC stream? - Does transcoding need to be set up in mythtv for HD channels (my understanding of the HD stream is that it contains all subchannels. Does mythtv filter out the "extra" subchannels or do you need to use the transcoding mechanism to reduce the file sizes?) I have no idea how any of this works in mythtv. And questions for performance: - What components of the mythtv / computer setup impact performance of HDTV (e.g., at a given hardware level, what is the CPU usage for recording? what is it for playback, what is it for both)? - Related to above, what is the impact of multiple HDTV captures (e.g., two HD-3000 cards) on the processing requirements of the PC? Anybody here yet? Anybody have an idea of what it takes processing-wise for HDTV PIP with two cards? - What can be done to improve performance (how is resolution reduced? Is there any impact (or even capability) of recording at lower resolution than 720p or 1080i/p? Is there an easy way to playback at different resolutions (via mythtv rather than different modelines). - If a modeline is set up for a particular monitor at a particular resolution, does that automatically reduce the processing of an HDTV stream (in other words, if I'm playing a 720p ATSC stream (1280x720) back on a monitor at 480p (704x480), have I somehow reduced the processing impact, or is the mythtv box still handling the full processing impact and all that is happening is a reduction in quality on the output)? - For playback, what is the processing impact for different resolutions (playing back a 720p stream at 1280 x 720, 1024 x 576, 800 x 450)? - For those trying to get the best performance (at the tradeoff of quality), what is the best way to play back HDTV? Reducing playback resolution? Transcoding to reduced resolution? etc. etc. - What about audio? Are there general rules about digital audio and performance or is this generally "not an issue" based on using a 5.1 sound card (e.g., SB Audigy)? - What is XvMC and how does / will that help with the processing requirements of HDTV playback? Are there particular video cards this will / will not work with? Anyone have real world examples of processing improvements (e.g., CPU usage) with XvMC and without? And a general question: - Is there a way to tell within mythtv what format the ATSC is being broadcast (720p, 1081i, etc.)? Wish I had more answers than questions, but as I get up the learning curve (and I receive my new, faster CPU), I should be able to contribute some real-world experience with my HD-3000 (and PVR-250 if I can ever get them working together). Thanks, Paul -- I hear and I forget. I see and I remember. I do and I understand. -- Confucius
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