[mythtv-users] HD MPEG2 ->SD DVD?

[Ma Begaj]

2008/7/14 Nick Rout <nick.rout at gmail.com>:
> On Mon, Jul 14, 2008 at 3:26 PM, George Mari
> <george_mythusers at mari1938.org> wrote:
>> Ma Begaj wrote:
>>> 2008/7/14 George Mari <george_mythusers at mari1938.org>:
>>
>> [deleted]
>>
>>>
>>> It would be great to be able to downscale video on the fly when a user
>>> wants to play HD recording or an HD Apple trailer in MythVideo with
>>> mplayer.
>>>
>>> Does downscaling video need more power than watching it? Probably
>>> little bit more and I mencoder or some other tool could do it. It
>>> could write the output in a new file, and mplayer on the
>>> notebook-frontend would read from it. I did not try this, but it could
>>> maybe be done for mplayer/mythvideo:
>>> 1. user runs a scripts which should start the video playing
>>> 2. the scripts connects over ssh to the powerful backend and starts
>>> downscaling the video and saving it in a new file
>>> 3. a few seconds later mplayer (on the frontend) starts with reading
>>> from the new file
>>>
>>> fast forward is probably not possible.
>>>
>>> what do you think about this idea?
>>
>> The slow part is not the scaling, it's the decoding of the MPEG2 file in
>> a time fast enough to get each frame onto the screen, before the next
>> one needs to be displayed.
>>
>> Lower bitrate HD recordings are easier for slower systems to display
>> than ones with higher bitrates, just because there is less data to
>> decode.  Of course the trade-off is a lower quality picture, in general.
>>
>> In order to scale the video, it first has to be decoded, so the
>> slow/hard part has to happen first before the easier part (scaling) can
>> be done.
>>
>> On-the-fly transcoding down to a lower bitrate and/or resolution would
>> be nice, but not generally doable, I think.  There may be something
>> similar going on with some of the streaming options that I believe
>> MythWeb has, but I'm not certain on this.
>>
>>
>
> VLC is a common way of people doing on the fly transcoding, but as you
> say it will require a lot of grunt on the backend.
>
> However a big barrier in this instance will be 802.11. Try a wired LAN
> and see what results you get before blaming it all on the CPU. :-)

802.11b is enough for SD. I can watch SD recordings without any problems if
recording is below 1.7-2GB/hour what is pretty acceptable.

I never used VLC for anything. mplayer was always enough. I will play with it
a little bit. But it still could only work for mythvideo, but not for
recordings.
Although I could make symlinks from recordings to mythvideo and watch recordings
with mplayer directly from mythvideo, but that is not very clear.