[mythtv-users] NUVExport slow export solution
Eric A. Cottrell
eac at shore.net
Sun Jan 30 11:35:34 EST 2005
Chris Petersen wrote:
>> nuvexport gets the output of transcode, parses it, reformats, and
>> prints it on the screen. It appears if the framerate gets over 20 FPS
>> then nuvexport can not process every status line guickly. The stdout
>> buffer fills thus stopping transcode until it empties. Reading the
>> transcode man page I came across the --print_status option in
>> transcode. I modified the transcode.pm file in nuvexport to add a
>> --print_status 4 option in the transcode command line. This tells
>> transcode to only print a status line for every 4 frames processed.
>> This fixed the problem and increased the rate back to a peak of around
>> 50 FPS when using nuvexport!
>
>
> I've added "--print_status 16" to the transcode options -- even 4 frames
> is probably overkill.
I suppose that will work as well. I wanted a value that would update a
couple of times per second in case it slows down.
> And am open to suggestions about how to do something similar with ffmpeg
> (nuvexport will soon be using ffmpeg for just about everything, since
> transcode doesn't seem to work with a bunch of mpeg type files), or even
> just speed up the buffering in nuvexport. In my tests with the mp3
> encoder, my settings were pulling 80-100fps, which I figured would be
> fast enough; apparently it doesn't carry over to the other encoder types.
>
>> I also noticed nuvexport will still use the -Z option when the output
>> resolution matches the input resolution. Transcode will still do zoom
>> when the -Z option is specified with no change in resolution thus
>> slowing down the frame rate for nothing.
>
>
> Yeah. I apparently gave too much credit to transcode. You don't happen
> to have a patch for this, do you?
>
Unfortunely I am not a perl programmer so no patches. I have figured
out enough to comment sections out or add strings. I am a C++
programmer that develops in Windows. In exchange I get money to buy
computer parts and build Linux computers.
>> Since my computer has a HT cpu I uncommented the option to specify the
>> number of CPUs in the transcode.pm file and gained about 1 FPS. I
>> noticed the first parameter for this option defaults to 10 but the
>> code in transcode.pm set it to 100. I used 10 and even tried 20 with
>> no change of framerate so I left it at 10. I assume 100 would be
>> overkill and may even slow it down like the comment indicated.
>
>
> Interesting. On my dual athlon, I found the exact opposite -- about
> 1.5-3 fps slower (nuvexport has multi-cpu detection included, but
> deactivated). Since transcode encodes both audio and video in separate
> threads, the kernel sends those to separate CPU's (which is what HT
> works as in this case). Creating another encoding thread just causes
> them all to fight for resources on the lesser-used cpu.
>
> Wouldn't be hard to add a commandline option to optionally enable this
> (since it would definitely help for something like a dual-xeon box)
Sounds like a difference between Athlon and Pentium that either the
operating system or transcode does not take in account.
Several months ago I got a Philips DVP-642. I want to convert my
saved programs to a mpeg4 format that is playable on the Philips.
I figured out settings that gave good quality on the computer but
so far anything I try using xvid is not playable on the Philips.
It seems other people have this problem as well. I burned a movie
trailer from the divx site and it played okay.
Most of the How-to information about xvid seems geared to windows users.
I recently discovered the xvid4conf program for linux. I am getting
stuff together slowly and may even write it down to help others. There
are several pieces that need to be setup for it to work.
NUVExport is a very useful program. My main usage is when I archive
shows I use it to get show information so I know what files to move. I
want to use it for converting files to MPEG4 format.
73 Eric
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