HDTV wishlist for MythTV


I have been building an HDTV PVR with MythTV and the pcHDTV tuner
card. It's been a major adventure, not yet ready for prime time, but
it's lead me to have some thoughts about things you want to think about
in a PVR that particularly relate to HDTV.

Suggesting new features is of course a somewhat futile activity. In open
source, the usually and appropriate answer is "why don't you go code up
this feature and add it?" In commercial products, most people feel
even the Tivo is too complex and they are correctly loathe to add
new features that complicate the user interface. So I make a priority
note on all of these.

If you are not familiar with certain linux video issues, some of this
will sound like gibberish.
Tolerate HDTV tuning problems
pcHDTV users are probably the only folks using MythTV with an
over the air antenna. In this case, signals can come in and
out, you might not be able to tune a channel and later you can.

Right now, failure to tune aborts a recording, and makes it hard
to restart. I think it's fixed now but for a while turning to
an empty channel crashed mythfrontend.

Priority: Fairly high, this is a bug fix really.

Smart Transcode
You have different transcoding desires based on the resolution at
which you recorded a program. You may wish to transcode your
480i to one resolution, your 480p to another, your 720p to another
and so on. However, since almost all available HDTVs only display
1280x720 resolution, you may definitely want to scale 1080i shows
down to that size (possibly with some deinterlace).

HDTV shows are big and you are keen to preserve space but you also
love quality. So it really becomes worthwhile to offer "transcode
to save space instead of delete" function, which predicts space
needs and transcodes down programs -- perhaps even in stages --
before needing to delete them. Watch it quickly and it's in
full resolution, later it's lower. Or just do it by time, based
on the class of recording. Ie. transcode down to a lower level
after a few days, further after a week.

Priority: Some of this can be done with minimal UI, so is good.
Some UI is needed because transcode with fixed resolution is not
very useful on an HD system (though at a basic level you can
pretty simply put in a check never to transcode to a larger
resolution if that's not already there.)

Realize CPU limitations
Decoding HDTV is intensive and can suck up a 3ghz level machine
almost entirely. Thus better XvMC support is in high demand.
However, some other features can be tuned to realize the CPU
problems. For example, de-interlacing and other filters should
turn themselves off automatically if they notice very high CPU
usage -- or simply if they notice the playback getting behind
at all. In general, if the system notices playback getting behind,
or dropping lots of frames, it should take whatever steps it can to
stop this. Even dropping quality, if it can be done adaptively
(ie. when CPU becomes available again or we get into a section that
is easy to decode because it is EDTV, turn things back on.
Priority: Medium. No UI needed here, but sometimes it's a simpler
answer to just let Moore's law fix it.

HDTV aware commercial detection
The fact that the screen switches from full widescreen to having
two fixed bars on the sides during commercials is, at least for
now, a major, major clue in detecting commercials. It's not
100% effective, so you can't use it exclusively, but it's close.

(Letterbox detection might also help for all TV but more and more
ads are being letterboxed.)

Priority: Zero UI needed, but not a crushing problem.

Be aware of aspect ratio mis-fits and use them.
Often these days there are black bars on the screen. Either L and R
for viewing SDTV on a widescreen, or top and bottom for letterbox.
If you see this happening, use that real estate for on screen displays,
including control, captions, subtitles etc. Consider a mode for
an always-on OSD with basic info (but unobtrusive, a very neutral
gray bar along the side showing position, channel, time etc.

Priority: Minimal UI needed (Just "do you want permanent OSD where
screen real estate permits it" checkbox) but not a crushing problem.

Pass necessary screen and aspect ratio to mplayer for DVD playback
In mythdvd, the aspect ratio information on the TV doesn't seem to
be always making it to mplayer. Also if you invoke
mythfrontend -display :0.1, this parameter is not inherited.
(I guess you can do export DISPLAY=:0.1;mythfrontend)

Priority: Minor Bugfix

Consider Two screen operation.
Today screens and multi-head video cards are cheap, and this
makes extra sense with an HDTV. Consider what you can do
with two screens. Video on the HDTV of course, but permanent
OSD on the other screen? Or PIP?

Priority: Hard to say

Support DTVLink/1394
New HDTVs are coming with firewire/1394 links, what is called
DTVLink. You can stream mpeg2 to the TV over the firewire,
or Camcorder DV format. Talk about ideal -- no need for even
a video card in the PC, and you can now do an HDPVR with an
old, slow machine. Of course, doing the menus etc. is something
I'm not as sure about with firewire video. Thus a 2nd screen until
it is easy to do that. This of course will generate the highest
quality image possible, you are feeding the delayed bits to the TV
it would have tuned if you had watched live.

Another 2nd screen option would be to take advantage of the fact
that DTVLink is a smart input -- the link is able switch viewing
from another input to the DTV stream and back again. So you can
do menus on one "screen" (going into the TV via ordinary inputs)
and switch to streamed mpeg. No OSD though.

To me this is the "pure" DVR. It records the digital stream,
and plays it back, and the decoding is done at the last step
before viewing. Though DVI is fairly close but not if you
do things like resolution changes etc. Add an ability to merge
text on top of the video and you have the pure PVR.

Priority: Higher as more TVs with 1394 come on the market.

Pay attention to AC-3 (6 channel audio) issues
Some of this stuff isn't as well tested and documented because
most people don't encounter it until they tune HDTV (or perhaps
some satellite boxes.)

Record all the time.
One of the important features of the Tivo is that it is recording
into the live buffer or a program's file all the time.
It never, ever stops. No matter what you do (other than change
channel) you can always go back to your live program. When you
sit down to first turn it on, you can go back into the buffer
of the channel it happened to be on.

With a DTV tuner (or a hardware mpeg encoder like wintv-pvr-x50)
there is almost no CPU cost to recording.

Plus it means if somebody says "watch live TV" it starts almost
right away, instead of waiting about 5 seconds.

And unlike the Tivo, don't erase the buffer just because I
change channels. Hey, why not let me go back in time to the
prior channel? Possibly pop up a warning about it based on a
flag in the stream. Then you can possibly change the nature
of the warning on channel change when behind in the buffer.
(BTW that warning should not be issued if you are only a few
seconds behind in the buffer.)

Priority: High -- this is a major function of the Tivo (to which
you will always be compared) which is missing. It's way to easy
to screw up your watching now and lose a program.

Realize that you can record 2 sub-channels of the same HD or QAM
master channel.

OK, I admit this one isn't likely to be easy, but an HD tuner
card is always receiving all the sub-channels of a DTV station.
Where I live PBS runs 4 different channels at once.

So I have to admit, a fancy tuner allocator able to make use of
his may be more work than it's worth. But you can improve
live TV channel change quite a bit here, make it close to
instantaneous, among the sub-channels at least. (Yes, even
though you are playing 3 seconds behind real time you can still
make it instantaneous.)

Priority: low

Realize that programs air in different qualities.
Yes, you can make one tuner more important than another, but
if a show airs twice either on different tuners or just on
different channels (such as the HD and SD versions of the same
channel) unless you say otherwise you would be disappointed if
the scheduler picked up the SD version and decided not to get
the HD one because it found the SD one.

Priority: low to medium

Show HD programs in the guide with a special colour or icon
Nice to quickly see this while browsing.

Priority: medium, because it's trivial



My name is Donald E Jackson, and I have over 25 years in radio as the morning drive host at various radio stations. On January 1st 2001, I started recording all major speeches by politicians, including those that were often not covered in a big way by the national press. I edited each speech down to single sound bites by topic, day, date, and speaker, most of which run from 30 seconds to 2 minutes but still retaining the entire speech. I also recorded Congressional hearings on important matters and followed the same procedure. I used these sound bites on my morning show each day. After the September 2001 attack on our country, I paid even closer attention and also recorded each press conference and Congressional speech, including those from the Department of Defense. Needless to say I have tens of thousands of audio files archived on my computer system, all searchable by topic, date, and speaker. When the war in Afghanistan was announced I recorded on new videotape MSNBC, CNN, and Fox News 24 hours a day 7 days a week until President Bush appeared on the deck of the USS Lincoln and stated “Mission Accomplished”. Those tapes have never been viewed and, in fact, are still sitting in my videotape library. I have since left radio, and as old habits die hard have slowly, over a period of months stopped collecting, editing and filing all of the major news stories each day. I do continue to keep current with the news and daily happenings around the world. Yesterday I was reading a news story that mentioned (but did not offer a link to) your site. After visiting your site I thought of all the news files and the entire war from 3 different perspectives that I currently have in my library. I say 3 different perspectives because there was an amazing difference in the coverage, not to mention the false reports, bias, and sometimes just blatant attempts to sensationalize our efforts in that campaign. But you would need to hear and compare in order to understand this point and besides that’s not the reason for my letter. It would seem to me the video war tapes, and the thousands of audio speeches and sound bites could comprise a wonderful library that, if given national attention, would draw tens of thousands of listeners and viewers to a web site.

Quite frankly I became almost addicted to the hunt and capture of the best quality most riveting speech or sound bite, and miss it dramatically. I have had one of the best attorneys in the country research the use of these broadcasts on the Internet and as long as they are used as news stories or for research it is completely legal. I want to go back to the hunt and I’m currently looking for a web site with enough bandwidth, money, and a desire to support such a library.

I also think there is a demand (not just a demand but a huge demand) for online information, which should include interviews with current newsmakers. Not just politicians, but people on the cutting edge of the latest technologies and newest innovations in all fields. Imagine being able to go online and search a file for everything John Kerry or George W Bush said by topic. Or for that matter going online and being able to watch one of the world’s great chiefs prepare a gourmet meal being able to stop, pause, or rerun it as you studied the technique the chief was using. I think America and maybe the world are quickly tiring of the networks telling us (to quote Walter Cronkite) “That’s the News”. All of this is possible with today’s streaming video as you so aptly point out on your web site, but it seemed to me you failed to mention the amount of money that various associations and commercial companies might be willing to pay for a chance to share their side of a current story. Here in Springfield, Illinois (the state capitol) as on a national level, the coal industry spends millions to promote clean burning coal, but the general public remains unaware, and in fact has been led to believe that coal is the most dangerous form of power currently in use in this country. No matter which side of this issue you take, certainly it’s obvious that both sides spend millions to offer the world one argument or another. Offering infomercials of this sort would, I think, offset the expense of the straight news and high tech sections? Now as a side note, and with all do respect, I listened to an interview of *Todd Herman on* Microsoft’s* **MSN Broadband Video Portal* when I visited your site.

First, as a past board member of the National Association of Radio Talk Show Hosts and as a 25-plus year veteran of talk radio, the interview did not do the subject or the guest justice. It’s my humble opinion if you’re going to capture the attention of causal browsers, or the average news hound and tech buffs, you need attention grabbing interviews that are going to offer anyone that listens new information grabbing the listener by both shoulders and saying “Hey here is something important that you need to know”. I say this as a constructive criticism and with thousands upon thousands of hours interviewing world leaders over the past 25 years. If any of this interests any of you in any way, please contact me using the below information. I wish you the world’s success in your pursuit of what I strongly believe is the future in both news and public information for the world. If you know of anyone beside yourself they may be interested in my project please pass this letter on to them.


Donald E. Jackson

1913 Pickett Street * Springfield, Illinois 62703


Your wishlist about exactly what I've been thinking of as well, except I'm looking at this from the European DVB-T point of view. It's interesting to learn that the same "tuning to a quiet channel" problem (MythTV freezing) affects HDTV reception as well.

Excellent list. My one small nitpick is that you take for granted that "most" HDTV sets are 720p native, thus all shows should be transcoded to that resolution by default. Two issues: First, there are a surprising number of *old* RPTV sets based on CRT technology which actually IS "native" 1080i. Second, although most DLP and LCD sets TODAY are 720p, I put to you that this will not be true in a year or two. The buzz this year at Winter CES was dominated by 1080p native display technologies -- DLP, LCD, and LCOS are all being introduced in sets this year.

Excellent blog, BTW!

I like your list, it contains many ideas I've had myself and a few I hadn't thought of. I actually made my own list of things I want to have changed or added to mythtv. I'm glad to know that there are others who are working to come up with improvements to MythTV. We just need some programmers who are skilled enough to impliment these changes. Can you help me get them done? Issac hasn't answered my e-mails. Here is my website: http://www.geocities.com/accpackard/MythTV.html

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