[Mplayer-users] Elementary streams (ES)

[Arpi]

Hi,

> > but i have a question to you, henning ...
> > do you have already a programm for watching divx via DVB-s on TV ???
> 
> No, I'm still looking at what's already available and what could be modified
> to be used. There is no ready-to-run program that can do the task at the
> moment. I have tried ffmpeg (http://ffmpeg.sourceforge.net) which can read
> and write a variety of formats and it looks very promising. However, it
> still has problems generating an  MPEG stream that can be understood by the
> DVB card and it's not fast enough to do the job in realtime on my PII/333
> DVB machine.
> 
> Could one of the developers perhaps comment on this: the DVB card has a
> built-in MPEG decoder that can AFAIK decode MPEG-1 and MPEG-2 streams. You
> cannot feed raw YUV data into it. Consequently, the existing video file
> (DivX, ASF, etc.) has to be converted to MPEG2 (MPEG-1 would be ok only for
> low-quality input files) on the fly. The easiest way would IMHO be to create
> an MPEG-2 stream consisting only of I-frames. What CPU is needed to do this
> in real-time (25-30 fps) and can this be done at all?
Strong. I think not the encoding is the problem, rather the bandwith.
You will get very high bitrate stream if using only I frames, and keep
high image quality. It can be even 10-20 MB/s. PC memory and PCI bus speed
will be the bottleneck...
And of course, you need a fast CPU to create this 10-20 MB/s steram from
single bits using VLC tables...

I still prefer using Divx -> MPEG2 I+P transcoding, using Q and MC values
from the divx.
Btw your p2/333 will be NEVER enough for this, as you have to decode DIVX
stream to YV12 frames, and then encode it to mpeg2. And the card will decode
it so it's triple work. The only way to get around this is transcoding,
but I don't know is it possible at all, I mean can one translate mpeg 4
parameters (Q bits and MC vectors) to MPEG2 "language". For example,
mpeg4 uses unlimited MC, so you can refer blocks outside of the image border.
Mpeg2 doesn't allow this.

> >From what I have seen so far, MPlayer would be a good solution but since the
> DVB card is no "VGA card running at TV-screen resolution" it would probably
> break the design of MPlayer?!
If it encodes from YV12 images, it won't. If it uses transcoding, it will.
But video conversion and encoding are planned features for mplayer, but
currently they are at low priority.

> BTW, the DVB card has built-in OSD functionality ;-)
Does it have nice antialiased fonts, like MPlayer's?


A'rpi / Astral & ESP-team

--
mailto:arpi at thot.banki.hu
http://esp-team.scene.hu

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