Problems with DVR-MS converted from MPEG

[pahunt]

I am having a problem with DVR-MS files that I create from MPEG2 files using VideoReDo Plus (version 2.5.6.512). If I take a .mpg file and drop it into "My Videos" I can watch it on my Vista Media Center (through an XBox 360) without any issues and everything works fine. However if I convert that .mpg to DVR-MS and drop it into the "Recorded TV" folder, I get very juddery playback and the skip buttons can cause the video to lock up for anywhere up to 10 seconds.

The specs of a typical MPEG file are:

Dimensions = 1280*720
Video Bitrate (VBR) = 6589Kbps

One point to note is that if I convert the MPEG down to a bitrate of about 3000Kbps before converting it to DVR-MS then the video becomes watchable but the I still get occasional lockups while skipping.

So my question is, is this caused by the way VideoReDo converts to DVR-MS or is it something inherently different about the way Media Center handles MPEG to DVR-MS?

[phd]

Are you watching all of the files through an Xbox?

When you say you convert the video down to 3000kbps are you using a third party application to convert the file or are you referring to changing the header bitrate with the Options button in VideoReDo?

[pahunt]

Yes, I'm watching the files through an XBox. The files that I am viewing, start off as AVI and I'm using ffmpeg to convert them to MPEG2. When I talked about setting the bitrate to 3000Kbps I meant I am converting the original AVI to MPEG2 again and telling ffmpeg to restrict the bitrate to 3000Kbps. I am not modifying the bitrate in the VideoReDo options at all.

[DanR]

Open the DVR-MS file in VideoReDo and click on Tools>Show Program Info. Please post those results here, there's a copy button in the lower left of the dialog.

How does the file play using MCE on your PC?

[pahunt]

And to answer the question about how the file plays on my PC, I don't know I'm afraid as it's a headless PC that has only got on-board graphics.


File Name: F:\Video Processing Queue\HD Test.dvr-ms
File Size: 0 ( 0.00 GB )
Program Duration: 00:05:00.03
File Type: DVR-MS
Encoding: MPEG 2
Video stream Id: xE0
Encoding Dimensions: 1264 x 704
Display Size: 1264 x 704
Aspect Ratio: 16/9
Frame Rate: 23.98 FPS
Bit Rate: 104.857 Mbps
VBV_Buffer: 6 KB
Profile: Main/1440
Progressive: Progressive Only
Chroma: 4:2:0
Audio Format: 5.1
Audio Stream Id: Raw PS1
Audio Bit Rate: 384 Kbps
Audio Sampling Rate: 48000 Hz

[DanR]

There are some issues with the source MPEG file:

1) Bit rate: 104.857 is wrong. You can adjust this with the output options on the file save dialog in VRD.

2) VBV_BUffer: 6 KB. That is wrong as well. Should be 976 KB. I don't know a way to change it. VRD doesn't have that capability.

3) Frame rate 23.98 FPS. That may be correct (probably is), but I don't know if DVR-MS files support that frame rate. Its not documented that they do (or don't). There really is very little documentation on DVR-MS files in general.

[pahunt]

Thanks for that, I am creating the source MPEG files using ffmpeg so I am just trying a slightly modified command line that should set the buffer size correctly and then I'll set the bitrate in VRD when I save it to DVR-MS.

[pahunt]

2) VBV_BUffer: 6 KB. That is wrong as well. Should be 976 KB. I don't know a way to change it. VRD doesn't have that capability.


I am having some fun & games getting ffmpeg to set the VBV_Buffer to 976KB, so I was just wondering how you know that is the right value. I have looked at some DVR-MS files that my Media Center has recorded (and that play back fine) and they have a VBV_Buffer of 224KB.

The issue I have with ffmpeg means that at the moment I am getting a VBV_Buffer value of 1192KB even though I am specifying 976KB. Do you think that might still cause a problem, or is a bigger buffer always better?

[DanR]

According to the MPEG spec:

For Main profile, main level max VBV buffer is 224KB (standard def)
For Main / 1440 (your video), max VBV is 896 KB (high def to 1440)
For Main / High, max VBV is 1194KB (high def to 1080)

The question which I can't answer is what happens with over/under values. It depends a lot on the playback software. VideoReDo ignores the VBV buffer size during playback as do most other PC-based software players. Don't know about the XBox.

[pahunt]

Apologies for reviving this thread but I've been busy over Christmas and haven't had much chance to look at this.

Anyway, this is the situation now. I am now working with a lower quality file and after converting it from AVI to MPEG2 using ffmpeg, I load it up into VRP, convert it to DVR-MS and I get the following detail on the Video Program Information screen:

File Name: F:\Recorded TV\HD Test.dvr-ms
File Size: 0 ( 0.00 GB )
Program Duration: 00:58:33.07
File Type: DVR-MS
Encoding: MPEG 2
Video stream Id: xE0
Encoding Dimensions: 480 x 384
Display Size: 480 x 384
Aspect Ratio: 4/3
Frame Rate: 25.00 FPS
Bit Rate: 9.000 Mbps
VBV_Buffer: 224 KB
Profile: Main/Main
Progressive: Progressive Only
Chroma: 4:2:0
Audio Format: Layer 2
Audio Stream Id: xC0
Audio Bit Rate: 128 Kbps
Audio Sampling Rate: 48000 Hz

Now as far as I can see everything looks right there (apart from the size saying 0GB) but I still get juddery playback through the XBox. But if I play the MPEG2 file (before the conversion to DVR-MS) through the XBox then it plays back fine.

Could it be that the DVR-MS format needs more PC resources to playback than the MPEG2?

[DanR]

The 480x384 seems wierd. Try having ffmpeg output it at a more normal, for PAL, of 720x576 and see what happens. If you can do it with ffmpeg, then use TVSuite to do it by outputting as a DVD folder than reading that folder back in and saving as DVR-MS.

I don't know if DVR-MS can handle all MPEG dimensions, there are lots of things about dvr-ms that aren't documented at all.

[pahunt]

Thanks Dan I'll set the dimensions to 720x576 and see what happens.

[pahunt]

Just in case anyone comes across this thread with a similar issue, I never did manage to get this to work properly. After tweaking every setting I could find in the mpeg output and getting nowhere, I re-installed MCE 2005 as an experiment and found that the same files that were unwatchable under Vista were rock solid under 2005. So I can only assume that my PC is too underpowered for Vista.