[mythtv-users] Use of Macintosh G4 as MythTV box

[Bob]

Greg Vickers wrote:
> Bob wrote:
> 
>>> If you use hardware encoding capture cards (DVB-T does this, and 
>>> analogue capture cards like the PVR-250) you don't need a lot of CPU 
>>> for the capture of the video.
>>
>> I believe the DVB cards actually don't do any encoding but neither do 
>> they do any decoding, they just stream the compressed video feed they 
>> pull of the air in whatever codec they receive it in (usually MPEG2), 
>> but the result is the same, both the hardware encoders (Hauppauge PVR 
>> cards) and the assorted digital TV cards place little demands on the 
>> backend CPU.
> 
> So if I had a DVB card to receive digital free-to-air and a Hauppauge 
> 350 to do the (analog) cable TV signal then the 350 would do the h/w 
> MPEG decoding for playback and I would probably be OK with a dual 450MHz 
> host, right? :P

Probably and if you have the hardware allredy it'll be fun finding out.

>> If the G4 is to be used as a frontend as well and CPU is a problem 
>> then you could output through a PVR 350 card (as long as your not 
>> planing to trascode stuff to MPEG4 for storage) or an nvidia card 
>> using XvMC (particularly as some of the new GPUs allegedly have MPEG4 
>> assistance) as both would assist with the decoding, but, I have *no* 
>> idea if either would work in a PPC environment.
> 
> Transcoding is converting from MPEG2 to MPEG4, right? Won't the 350 
> decode both MPEG2 and MPEG4 streams for playback? 

Not necessarily, transcoding is the process of changing the codec that 
the video is stored with though in this case I was talking about from 
MPEG2 -> MPEG4 and apparently the PVR 350 won't do MPEG4 playback.
http://www.gossamer-threads.com/lists/engine?list=mythtv&do=search_results&search_forum=all&search_string=pvr+350+mpeg4+playback&search_type=AND

> There's an ATI rage 
> 128 pro in there right now, I've got a Matrox G450 to drop in there as I 
> have the cable that will adapt the Matrox video display on the second 
> head to an S-video and composite display. Hmm, five minutes of tinkering 
> and the system won't give me any video with the Matrox in there... fell 
> at the first hurdle! I wonder if this converter cable will work with the 
> ATI card ...
 >
> Can you can schedule transcoding to be done when the system is idle? 
> i.e. when you are not watching 'live' TV through the system?

yes

> So if I had the funds available, I could go out and get a DVB card, a 
> Hauppauge 350 and a video card with TV out and I'd be set with this dual 
> G4 450.
> Or I could get a bigger CPU system and a DVB card and some other analog 
> card to capture the cable TV channel.

I'd get the DVB card and a PVR 500 or 150, then give it a go with your 
current hardware, if you can't get it to work then get a new box and 
transfer the cards over.

> Oh yeah, we also have a 76 cm flat-screen CRT TV as well - will I have a 
> consideration when it comes to sample rate and subsequent playback rate 
> given a large TV?
> 
> Thanks,


-- 
tveeprom: Hauppauge: model = 34132, rev = J158,
tveeprom: tuner = Philips FM1236 MK3 (idx = 58, type = 4)
tveeprom: audio_processor = MSP3416 (type = 14)
(new type Model 401)
model name      : mobile AMD Athlon(tm) XP Processor
cpu MHz         : 2277.214
cache size      : 512 KB
(Plenty o' grunt on an ECS k7s5a MB)
Knoppmyth R5A16 (unmodified)
http://mysettopbox.tv/CHANGELOG.txt
MythTV 0.18.1