HW MPEG2 Decoder support

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lmatter
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HW MPEG2 Decoder support

Post by lmatter »

Via have offered to build their binary-only drivers, including MPEG2 decoder support, for minimyth. I have spent the last few weeks working with one of their engineers getting it working, and I didn't want to say anything until it was. Thus the seemingly lack of progress lately.

It is now working on my test system, but there are some issues. The picture looks fine, and the CPU utilization is around 30% with 640x480 MPEG2 (from a PVR-350) but there is some jerkiness that is not there when not using the HW mpeg2 decoder (with CPU at more like 80-90%).

I want to get this resolved before I make an announcement on the home page, and anyway, I'm not that close to releasing 0.2, but for you loyal forum readers, I wanted to let you know.

I want to thank Via for helping me with this. They have been very supportive and responsive to me and minimyth.

BTW, this means that the kernel version will not upgrade for a while unless there is a really good reason to do so.

Also, this is obviously a temporary thing until usable open source drivers are available, which could be a while.

Larry
Last edited by lmatter on Fri Jan 30, 2004 9:41 pm, edited 1 time in total.
AndrewDV
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Post by AndrewDV »

That is great news! That would make my ME6000 actually usable for MPEG playback.

Thanks for the work!
stevew
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Post by stevew »

:D That's great news indeed!
This project just keeps getting better and better.
Thanks and keep up the superb work.
Steve
lmatter
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Post by lmatter »

Just want to follow up a bit. I played with reducing the bitrate of the PVR card (in setup/tv settings/recording profiles) and lowered it to about 6000/5000. This seemed to help the jerkiness quite a bit, but did not get rid of it entirely. It still stutters when the OSD is transitioning. This has the effect of making the video/audio get out of sync. A quick pause/unpause fixes this. I also changed the shading of the boxes to "none", although I left the "transparent boxes" checked so the watch recording screen looks nice.

The lower bit rate hasn't seemed to reduce the quality of the image either (on a small TV, anyway). I'm going for 720x480, btw. I need to play with it a bit more, but I haven't had much time lately.

If anyone wants to play with the MPEG2 support, send me an email or PM. I'm still a ways off getting a release out.

Larry
mrmoray
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How's this going?

Post by mrmoray »

Larry,

I'm about to embark on an Epia M10000 myth frontend only project and I'm wondering how much success you've now had with the hardware decoding? It sounds like you've got it working but maybe not as smooth as you'd like?

One thing I don't quite understand (forgive my ignorance)..but how is what you're doing with these binary drivers different from what Isaac has implemented for hardware decoding in myth? I know myth can now use the epia hw decoder, and it can use the PVR 350 as well, but I don't understand your implementation is different from his, or is really the same?

Thanks,
Mike
lmatter
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Post by lmatter »

All I did, really, was to convince Via to "port" their binary-only drivers (which includes support for the onboard MPEG2 hardware decoder) to my distribution; like they do for stock versions of Mandrake, RedHat and Suse.

What Isaac has done is to enhance mythfrontend to make use of those drivers.
mrmoray
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Thanks!

Post by mrmoray »

Geez...I'm an idiot. Thanks Larry, I get it now.

So...you're still dealing with some jitter? Sure would be nice to get this thing running super smooth. In my mind, MiniMyth is the ideal solution for a FrontEnd only. I can't wait to get my equipment and get started.

Thanks Again!
sw25481

Keen to help out

Post by sw25481 »

Larry,

I've been staying away from minimyth only because I have hardware MPEG support in RedHat 8 running with what was CVS of Myth until 12 came out, (not updated yet), on a 933MHZ HushPC. I have the PXE infra ready to go, PVR 250 in the server, (and DVB) and would love to help out with testing/bug fix/docs whatever. Could you consider posting what you have of Alpha-2, jitters included, no instructions, features missing, only for the brave/stupid, no apologies needed, etc so we can start hacking about and feeding back patches. Later perhaps let us know anything you are unlikely to get round to for a while and would like help with so we can show apreciation for a cracking project.

Scott :?:
sw25481

You must have read my mind

Post by sw25481 »

Larry,

You must have read my mind. I'm sure I need say nothing more and let you anounce when your ready

Scott
lmatter
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Post by lmatter »

A release candidate of minimyth-0.2 is ready. Please try it out.

http://linpvr.org/rel-0.2/index.html

You need a new kernel; you can get the one from the page above or build your own based on the available .config.

If it looks good, I'll update the main page with this one.

Larry
Nem
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Post by Nem »

Larry,

The version of Mythtv in the uncrammed image doesn't seem to work. I think its an incompatibility between the compile of Myth and the compile of the Mythlib.

Regards,

Darren
lmatter
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Post by lmatter »

ok, I'll take a look in a few hours. Thanks for trying it.

Larry
lmatter
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Post by lmatter »

I re-uploaded the uncrammed image, taken from what I am actually using right now and it is working for me.

Followups here please:
http://www.linpvr.org/forum/viewtopic.php?t=44
michaelshiloh
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Some clarification of the history and status

Post by michaelshiloh »

I asked Larry to clarify the status and usage of the hardware decoding. Larry replied eloquently, and I trust others will find this information useful:
In MiniMyth v1, there were no Linux drivers for EPIA hw decoded. And I was using the cheaper bttv cards (and encoding in mpeg4) so it didn't matter much.

Then Via (finally) produced Linux drivers, but they only worked with a few stock kernels - rebuild the kernel and the driver probably wouldn't work anymore.

Isaac added support to MythFrontend to use these drivers instead of software decoding.

Then Via graciously offered to build their drivers for the kernel I was using in MiniMyth so I was able to provide hw decoding support for MythFrontend. That was MiniMyth v2. That's when I needed to play symlink games to allow switching the HW decoding on and off.

Then Ivor and others reverse engineered the Via drivers so I was able to use their versions (which were not tied to a specific kernel version) and so I came out with MiniMyth v4.

Mplayer (and other players) do not take advantage of the hw decoder drivers, but rather use software decoding. I do not know much about encoding/decoding, but my understanding is that the Via drivers only provide some assistance to the process of decoding (like doing a bunch of the math) but don't do the full decoding. So it is not that simple to make use of the drivers.
sw25481
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Unichrome Xine

Post by sw25481 »

Just wanted to let you know I have had much success with the Unichrome patch for Xine that uses the Unichrome XvMC drivers for the hardware MPEG decoder in the CLE266 chipset.

Lot of work I guess to shoehorn into MiniMyth, but at least there is a possable way forward now. I've had more success on 2.6 that 2.4 though, but lets hope that's just me.
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