[mythtv-users] HDMI capture card with linux drivers

Douglas Peale Douglas_Peale at comcast.net
Fri Apr 16 05:24:36 UTC 2010


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Raymond Wagner wrote:
> On 4/16/2010 00:07, Yeechang Lee wrote:
>> Raymond Wagner<raymond at wagnerrp.com>  says:
>>   
>>> Their software... meaning it has nothing to do with the hardware or
>>> the drivers.
>>>      
>> That's can't be right; my understanding is that it's impossible for a
>> general-purpose consumer-priced computer today to real-time encode HD
>> video into high-quality h.264. (Otherwise someone by now would've
>> written such an encoder and turn any simple hardware framegrabber into
>> a HD-PVR equivalent.) Or am I mistaken?
>>    
> 
> I'm saying it is their software that captures to MJPEG, not the
> hardware, not the linux drivers.  If MythTV were to support this device,
> it would use its own encoding mechanism, be that RTJPEG, MPEG4, H264, or
> whatever.  VDPAU support would not factor into the equation, since the
> fact that the Windows software uses MJPEG has no bearing what-so-ever on
> what MythTV would do.
> 
> Furthermore, compression is almost always asymmetric, with compression
> taking far longer than decompression.  Any machine capable of capturing
> and compressing such video would easily be able to decompress it later. 
> Hardware acceleration would not be necessary.
> _______________________________________________
> mythtv-users mailing list
> mythtv-users at mythtv.org
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
> 
Lets do a bit of math here.
1920 pixels * 1080 pixels * 3 bytes * 30 frames/second = 186,624,000
bytes/second.
There are very few hard drives that can be written that fast.
Your computer could do nothing else but write the disk, so there is no
possibility of encoding while recording.
So you want to record a 2 hour movie, that is 186,624,000 * 60 * 60 * 2
= 1,343,692,800,000 bytes.
So it would require most of one of the largest hard drives available
today just to store the unencrypted file.

This is not really practical.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.9 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iEYEARECAAYFAkvH9IkACgkQe5tReOauESoS+gCfYqdshYC3NCer72oYBhrujPPb
KZ8AnRYanfWI9nrkUWjpIyh7qX+owTCG
=x7tq
-----END PGP SIGNATURE-----


More information about the mythtv-users mailing list