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Pre-alpha HDTV playback

Started by stu-e, February 17, 2010, 13:16:25

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I do not have a Windows system which I could volunteer to test HDTV playback but I am curious about this.

What are the software requirements at the moment? Does it work with XP, Vista or Windows7?

Depending on hardware support, how is hardware decoding and most importantly deinterlacing enabled?



You need a h264 decoder, which works with vomp. (Unfortunetely a lot of new decoder only work in the application with which they are shipped). Which one these are, has to be tested. I used the standalone video decoder from mediaplayer classic hc.

A vdr version with build-in HDTV support is needed (at least a version writting recordings in TS format). HDTV playback is only in TS recordings supported.

It should work on XP, Vista, Windows 7 (untested). Hardware decoding is enabled, if the decoder filter supports it and if you use VMR9 under XP and EVR under Vista, Windows 7(?). (Can be selected in the option menu).
Deinterlacing can be controlled as before using the VMR9, for EVR I do not know it, but assume it might be turned on as default inside the EVR.

There might be several problem with especially HD playback. I assume that several network buffer need to be adjusted, but for this I need feedback from the alpha test.



I tested this last night on three different laptops, with three different reactions..

I have five different types of channel:

ATSC SD with ac3 audio
ATSC SD with mp3 audio (via steamdev / fmpeg and vdr-iptv - a cludge to allow my hardware mvp's to work)
ATSC HD with ac3 audio
a Hauppauge PVR HD, which works via pvrinput, H264, ac3 audio
PVR 500 anlogue MPEG2, mp3 audio

I loaded ac3filter to handle the audio on all PC's. All PC's also have

Laptop 1.  An Asus, with GMA900 graphics chipset, powerdvd 9 codecs..  Vista Ultimate  via WIFI..

Everything worked, but not well, lots of stuttering.  The h264 worked better than the mpeg2 ATSC HD stuff, but I think the bitrate would be lower.

PC Pentium 4 with Intel Graphics, XP..  Wired ethernet

This was the worst of the three. 

Selecting ac3filter crashed vompclient immediately.  I had to go to the server and manually edit the config file..

ATSC with ac3 audio stuttered horribly.
The reencoded stuff was a little better, but only a little..
H264 refused to play completely.
MPEG2 HD updated the picture about once every 10 seconds..

Laptop 3, ACER Aspire 5920G, Dual Core with Nvidia 8600 GFA.. Wifi..

This was nice and fast, and played everything, but the HD content was playing back wrong.. I think it was the vframe issue pointed out elsewhere, it looked like two videoprojectors were pointing at the same screen but one was out of sync slightly...

Recordings played back better than live tv..

Old HD MPEG2 ATSC recordings made under VDR 1.6 didn't play at all, but I think we knew that..

I am in the process of compiling a CVS hardware dongle so I can leave the cvs server code in VDR and the hardware mvp's will work.. Once done I will try testing again..

I noticed the media code was missing in the beta test..  Will that be missing in the latest cvs hardware version too?


The media is only disabled in the windows part. I have just no time to test this for the changes in the devices.

For laptop 1:
I know that there are issues with the network, please try if adjusting the TCP window size helps.
Just for the records, this stuttering does it happen also on recordings, which played back fine with older versions?

Which video filter is selected in the options VMR9 or EVR? Is the dts fix option selected for mpeg2 or h264?

Please look which H264 decoder is selected in the property menu.

For PC 2: Sounds for me, as if the computer is too old for h264 playback.

For all test scenarios with stuttering and wrong playback try the dts fix option for mpeg2 and h264. Some filters are buggy and thisone fixeds the problem or introduces new problems so it would be good to know which filters neede it.



Some more testing with two of the laptops and the version 2 of the Vomp for Windows..

One the faster laptop with Nvidia graphics,

I used Cyberlink DVD 8 codecs for mpeg2 and h264. 

SD with AC-3 audio, audio is horribly out of sync.  My guess is this is working as a by product of the development, but in ATSC land this is a biggie.  Comcast (the largest cable company) is broadcasting 60 or so premium channels in the clear as they're shutting off their analogue channels.  So we have 8 HD channels and 60 SD ones, all of which are ac-3...

MPEG 2 HD with ac-3, with EVR the picture is distorted as I wrote before.  With VBR picture is good, audio is pretty much in sync.. Although there are framedrops.. TCP size I have up at 16384..

H264, picture quality is good, but only works with EVR (the opposite of above).. Audio stutters.  It doesn't seem to make much difference if I select the dts option is selected.

Didn't yet test a recording.. Will do so and report back..


Actually Ac3 should be in sync, at least at my machine it was. Try to switch the channel forth and back, this will lead to a rsync. If pts are present in the original stream, video and audio should be in sync (try also the dts mpeg2 fix option iin off and on mode).
Are recordings in sync? Which audio decoder do you use?

Actually, I never had a Mpeg2 HD for testing can you give me a short sample (or was one of the previous samples mpeg2 hd), I have an idea, what might be wrong. (PS: was it on vista?) 

For the h264 and the audio stutter, is it with evr or vmr9 and how high is the cpu load? Please check this, if it does not work, please tell me your type of network connection, I may supply some test version with different intermediate buffer sizes.



Am just about to go out, so I'll do some more testing later, but as a note, my other laptop, both EVR and VBR work with mpeg2, this has an intel graphics card.  This is also Vista.

This laptop however, I don't think has the power to decode h264 properly, at least at the bitrate it's being fed at..

The samples I sent had an MPEG 2 with HD, the pbs one, the other two were H264 (HD) and Mpeg 2 with ac3 sounds in (SD) from CNN..

Recordings exhibit the same characteristics but quality is slightly better.


QuoteMPEG 2 HD with ac-3, with EVR the picture is distorted as I wrote before.
With this distorted picture was this also pbs, beciause pbs played just fine on my machine. I have two assumptions, one would be a problem with certain picture sizes (pbs was 720p, if it is on 1080i I might have missed something for mpeg2 in interlaced mode), the other would be a problem with the data flow.
So if doable a screenshot would be nice, also a part of the log around this play back. (please not the whole file just around the times of playback can be helpful. (Is there something like TS misaligned?)

Ok you just said the quality of recordings is slightly better, this suggest problems of the data flow, I will generate on the weekend test versions with different network buffer sizes or overload of the cpu.
Note: VMR9 might lead to better picture quality, but under vista all decoding is then done in cpu, whereas EVR uses the hardware decoders of the graphics card(on xp it is the otherway round)-