Stuttering and Software Encoding TV cards

[Hivanoe]

Hi all,

this may be not new for someone, but I didn't read this on documentation ...

With software encoding TV tuners (the supported types) , when you watch analog channels (not recording or timeshifting), MP encode the analog signal to MPEG2 anyway, than it decode the stream again to show it on the monitor screen.

I read on DOC that a P4 2.8Ghz is required for software encoders ... but I supposed "... if you want to record or timeshift", instead such CPU is also required if you want to watch only :

I have a Pentium4 2.4Ghz with stuttering problem on analog TV channels:
With TV capture resolution to 720x576 (PAL on my country) MP cannot encode and decode the signal again ... so I have stuttering problems (CPU at 100%)!
By changing TV capture resolution to 352x288 (CIF) my CPU can do the job at 60% load ... so I have NO STUTTERING !

So, not a codec problem, or vga drivers, XP patch ... but CPU power limit .

Attention, this is not a "real problem" ... it's the MP approach to "software encoding tv cards".... you need a really fast CPU !

The TV software that came with my tv adapter works PERFECT with my CPU ...
This is possible: because such software capture the analog signal and send it directly to LCD monitor UNCOMPRESSED, without the MPEG2 encoding step.

My question is: can MP handle the Analog signal without compressing it to MPEG2 ?
I think no....
I tried to change filters connections to skip the encoder ... not successful, I think MP needs an MPEG2 stream.

Bye.

[infinityloop]

question: which Videocard (GPU) are you using? is it DirectX9 compatible?

generally speaking, we always recommend hardware encoding cards simply because of such issues as you report above.

The CPU has to do all the mpeg2 software enconding for your card, even if you are "only" watching MyTV.
The software which is bundled with that sw-encoding cards, simply is not doing any mpeg2 encoding. it is saving your recordings as avi.
thats why they do not require a "strong" CPU.

[Hivanoe]

I have Nvidia geforce 6200a AGP, (DX9, VMR9, Purevideo).

The sw bundled with my TV card (FlyDVB Trio) records in MPEG2 (I'm sure) !
But, if I watch only, it uses acquired video uncompressed directly di the monitor; CPU load is an average 15-20% when watching.

It starts encoding only when I press RECORD, in that situation (recording and watching) CPU usage goes to 90-95% (P4 2.4Ghz)

MP, with my CPU, cannot do the same thing at the same time, For me because it encode/decode MPEG2. The bundled other TV app doesn't decode the just MPEG2 encoded stream, it continue using the uncompressed video (before the encoding step)

This is what I think:


MP (CPU load 100%, stuttering)
-------------- . . . -------- . . . .--------
|Uncompressed.|. . .|Encoding| . . .|decoding|
|video. . . . |---->|to MPEG2|----->|MPEG2...|----> show video to Monitor
-------------- . . . -------- . . . .--------
. . . . . . . . . . . .|
. . . . . . . . . . . .V
. . . . . . . . . record to disk


Bundled TV card software (CPU 90%, no stuttering)
------------- . . . --------
|Uncompressed|. . .|Encoding|
|video . . . |---->|to MPEG2|----> record to disk
------------- . . . --------
. . .|
. . .V
. show video to Monitor


There may be a 10-15% CPU load difference between the two methods ... related to CPU power !

It's true that an hardware encoding card whould be better ...
But with the growing cpu power ... and digital TV becoming more popular ... what's the future of analog hardware encoding ?

Now .. if I want more than 352x288 resolution on analog TV I need an hardware encoding card ... or a new CPU !

Thank you for your reply.
Bye