[mythtv-users] Direct software mpeg-1 encoding(live)

[Joseph A. Caputo]

On Tuesday 27 January 2004 09:55, Dhiraj Gaurh wrote:
> Hello friends,
>   Some time ago I had written a mail to this list saying that it
> would be very nice if we could encode in mpeg-1 (or 2 if you please)
> directly, rather than encoding in mpeg-4 and later transcoding it to
> mpeg-1. Many people on this list said that it is not possible to do
> mpeg-1 encoding in software as it consumes too much CPU. It sounded
> rather strange to me that it was possible to do live mpeg-4 encoding
> but not mpeg-1. I thought since mpeg-4 compresses more so it should
> require a faster CPU. It turns out that I was right. I was just
> looking at the freevo page(another free Linux PVR application). It
> says it is possible to do direct mpeg-1 VCD quality encoding using a
> Celeron 400 MHz but mpeg-2 and mpeg-4 require more CPU power. This
> seems to be a true statement. It is possible to directly make a VCD
> file with Freevo, zapping or the standalone mp1e library.So now, if
> you can't do live mpeg-4 encoding and you don't have enough disk
> space to store your recorded RTJPEG or if you want to make a VCD
> anyway and don't want to bother about transcoding from RTJPEG/mpeg-4
> to mpeg-1, you can do it !! That's really nice. It will be quite nice
> if we include direct mpeg-1/2 encoding support into mythtv. That
> would be a very nice and useful addition. Let me see what I can do
> about it. If I get some time. It will take a few months if I have to
> do it myself though. The actual work itself shouldn't take a lot of
> time though. The encoder is already there, you just need to put a
> hook into mythtv to make use of it. Seems rather simple to me.
> Perhaps there are reasons why mythtv would not want to use mp1e or
> rte but I am not aware of them. As far as I know, they are open
> source.


I believe the previous thread was regarding software MPEG-2 encoding 
only, and I believe that most folks don't have the power required to do 
realtime MPEG-2 encoding in software.  MPEG-1 was never really brought 
up because most people don't seem to be interested in the limited 
quality you get out of a VCD-compliant MPEG-1 stream.  VCD is 
fixed-bitrate (1150 or 1250 IIRC) and the quality is not all that 
great, IMHO.  MPEG-2 is desirable because it used in both the SVCD and 
DVD standards, which both allow for better quality, higher bitrates and 
(for DVD) multiple resolutions.

That said, I'm certainly not against MPEG-1 if someone wants to do the 
code, but I suspect you'll find little interest in adding the support.

-JAC