WMP10 - why this distorted MPG?

[terrypin]

I produced an MPG test file in Womble MPEG Video Wizard. I've uploaded it here (26MB):
http://www.speedyshare.com/617700187.html

As you see from this GSpot report extract, its size is 640x480, i.e. an AR of 4:3.

--- Video Information ---
Video Codec Type(e.g. "DIV3"):
MPEG2
Video Codec Name(e.g. "DivX 3, Low-Motion"): MPEG-2
Video Codec Status(e.g. "Codec Is Installed"): Codec(s) are Installed
Duration (hh:mms): 0:02.000 Frame Count:
50
Frame Width (pixels): 640
Frame Height (pixels): 480
Storage Aspect Ratio("SAR")" 1.333 Pixel Aspect
Ratio ("PAR"):
Display Aspect Ratio ("DAR"):
Fields Per Second: 50.000
Frames Per Second: 25.000
Pics Per Second: 25.000
Video Bitrate (kbps): 33554

It plays fine in various of my players - except WMP10, where it displays square instead of 4:3. Is there some setting I've so far not found in WMP10 that is causing this please?

--
Terry, East Grinstead, UK

[Baldrick]

What mpeg2 decoder is wmp using? You can use windows dvd decoder checkup utility to check and also change decoder if you have several installed, download from http://www.microsoft.com/downloads/details.aspx?FamilyId=DE1491AC-0AB6-4990-943D-627E6ADE9FCB

[thecoalman]

Plays fine for me in WMP, that's usually the noraml behavior. AR and resolution are two seperate things. You could for example have two DV-AVI files that are 4:3 and 16:9 with a resolution of 720x480 . WMP will play these correctly. The rest are hit and miss, the same is true of other players.

I'd check your settings in WMP.

[terrypin]

Baldrick: Many thanks, looks like you've identified the issue. Installed and ran that utility and it told me I had just one mpeg2 decoder, called AVSMPEG2DecoderFilter.ax 1.1.0.140, incompatible with WMP10.

The subject of codecs is still largely a black art to me, so can you advise what I should do next please. I'm sort of surprised because I work with MPEG2 a lot to make family DVDs, using several programs (like Womble, MemoriesOnTV, VirtualDub-MPEG, etc). I don't use WMP10 much though, as I usually play MPG with MediaPlayer Classic, or PowerDVd, or even VLC.

thecoalman: Still not sure I follow, so would appreciate a bit more help on this please. Why the different result in different players? And if the file is 640 x 480, how can it get displayed as square? Is it something to do with PAR? I was puzzled why GSpot didn't show an entry for that.

--
Terry, East Grinstead, UK

[jagabo]

The file you uploaded isn't an MPEG file. It's an uncompressed RGB AVI file.

[terrypin]

Thanks jagabo. Sorry, you're quite right, my stupid error!

I had also posted to rec.video.desktop earlier this afternoon about the related problem of how to get the AVI rendered properly in Womble MPEG Video Wizard. That's the thread for which I uploaded the AVI file, so that other Womble users could try rendering it. I then posted this thread about the subsequent problem of the distorted MPG file in WMP 10, and should have uploaded that MPG file, not the AVI.

I'd like to be able to do so right now, but (a) I can't find it in the scores of working files I've now generated, and (b) I have made some progress and I think I'm close to sorting it myself. I've made another few files since by customising Womble's export settings, in particular setting the PAR to 1.00. The resultant MPGs have displayed correctly in WMP 10. But I'm going to repeat the entire exercise methodically asap, and will come back if I still have a major problem.

Sorry about the confusion!

Now, that leaves the issue arising from Baldrick's original reply. If I don't have a 'WMP10-compatible' MPEG-2 Decoder, which appears to be the case, how is it playing these MPGs at all?

BTW, when playing a file in WMP 10, is it possible to see the extension as well as the filename somewhere please?


--
Terry, East Grinstead, UK

[jagabo]

Now, that leaves the issue arising from Baldrick's original reply. If I don't have a 'WMP10-compatible' MPEG-2 Decoder, which appears to be the case, how is it playing these MPGs at all?

I think that tool only indicates if the decoders are "certified", not whether they work or not. Try playing your MPG video with MPlayer2.exe (found in the same folder as WMP 10). Select File -> Properties -> Advanced. That will show you a list of filters being used to play the file.

BTW, when playing a file in WMP 10, is it possible to see the extension as well as the filename somewhere please?

File -> Properties.

Oh, this also indicates what video decoder is being used.

[terrypin]

I think that tool only indicates if the decoders are "certified", not whether they work or not.

I got the following extra info when I highlighted that entry AVSMPEG2DecoderFilter.ax:
"This decoder is not compatible with the synchronization feature of Windows Media Player 10. We recommend against setting this decoder as the preferred decoder."
So, although I'm not sure whether it's 'certified' or not, it seems to be inadequate in that one respect, 'synchronization'. What is that please? What symptoms should I expect as a result? And, assuming I continue not to click 'Set as Preferred', does that mean WMP10 is not using it at all to play MPGs?

Try playing your MPG video with MPlayer2.exe (found in the same folder as WMP 10). Select File -> Properties -> Advanced. That will show you a list of filters being used to play the file.

Oh, this also indicates what video decoder is being used.

Thanks, that's very handy. I may switch my MPG association to MPlayer2instead of the present MediaPlayer Classic. (What do you have associated, BTW?) Anyway, it does show some hopefully useful information, although doesn't mean much to me I'm afraid. Here are the key points:
Filters in use: Nero Splitter, Nero Video Decoder, Video Renderer
Codecs in use: (Blank)

Properties for Nero Video Decoder:
MPEG-1/2/4 & AVC Video Decoder, (c) 2005 Nero AG
Options (None are set)
----------------------
Use DirectX VA if available
Use auto post-processing (with 'PP level' slider)
Use Line21 / Mpeg-4 SP Video Padding

Can you outline roughly what all that tells me please? Does it mean I have a Nero MPEG-2 Decoder installed? If so, why didn't that appear as another entry displayed by DECCHECK?

More to the point, is all well, or is there anything I perhaps need to fix?

BTW, several of these players are not displaying the MPG (encoded from that original AVI) in the original aspect ratio (4:3). I'll study this issue and if still baffled (I get very confused about aspect ratios) I'll post again.

--
Terry, East Grinstead, UK

[jagabo]

I got the following extra info when I highlighted that entry AVSMPEG2DecoderFilter.ax:
"This decoder is not compatible with the synchronization feature of Windows Media Player 10. We recommend against setting this decoder as the preferred decoder."
So, although I'm not sure whether it's 'certified' or not, it seems to be inadequate in that one respect, 'synchronization'. What is that please?

Sychronization refers to the mirroring of audio and video content on a portable player. This is probably nothing to worry about if you're not using a portable player.

I may switch my MPG association to MPlayer2instead of the present MediaPlayer Classic.

MPC can give you the same information, even more, by selecting Play -> Filters. Or right clicking on the video and selecting Filters.

(What do you have associated, BTW?)

My main player is KMPlayer. But I use several others on occasion: Mplayer2, MPC, WMP 10, VLC, and Divx Player.

Anyway, it does show some hopefully useful information, although doesn't mean much to me I'm afraid. Here are the key points:
Filters in use: Nero Splitter, Nero Video Decoder, Video Renderer
Codecs in use: (Blank)

Properties for Nero Video Decoder:
MPEG-1/2/4 & AVC Video Decoder, (c) 2005 Nero AG
Options (None are set)
----------------------
Use DirectX VA if available
Use auto post-processing (with 'PP level' slider)
Use Line21 / Mpeg-4 SP Video Padding

Can you outline roughly what all that tells me please?

Directshow pieces different modules, or filters, together when it plays a multimedia file. You will typically have a file reader, a file splitter, a video decoder, an audio decoder, maybe a colorspace converter, an audio renderer and a video renderer.

The file reader is responsible for reading data from the file, maybe some read ahead buffering, etc.

The file splitter splits the audio and video data into separate streams for further processing.

The audio and video decoders decompress audio and video data.

A colorspace converter will convert from one colorspace to another. For example, if the video decompressor can only decompress to YV12, and the video renderer can only output RGB32, a colorspace converter will be used to convert YV12 video to RGB32.

The audio and video renderers take the decompressed audio and video and sends them to the audio card and the video card.

There may be several filters capable of performing the same task so there is a merit, or priority, system to select the preferred filters.

The list you get from Mplayer2 is telling you that Nero Splitter is being used to split audio and video into separate streams, Nero Video Decoder is being used to decompress the MPEG2 video, and Video Renderer (a DirectShow filter) is being used to send the decompressed video data to the graphics card.

Note that it's possible for an application to build its own filter graph rather than having DirectShow build it. MPC, for example, prefers to use its own MPEG2 decoder.

If you want to play around with building your own filter graphs try out Microsoft's GraphEdit.

Does it mean I have a Nero MPEG-2 Decoder installed?

Yes.

If so, why didn't that appear as another entry displayed by DECCHECK?

I'm not sure why it doesn't show up. Maybe because it's not primarily an MPEG2 decoder? Or maybe it's a Video for Windows (VFW, an older Windows video system) driver rather than DirectShow.

More to the point, is all well, or is there anything I perhaps need to fix?

Not unless something is broken. There are programs for managing DS filters. FilMerit, RadLight Filter Manager. Be careful though, it's possible to screw things up using those tools.

BTW, several of these players are not displaying the MPG (encoded from that original AVI) in the original aspect ratio (4:3). I'll study this issue and if still baffled (I get very confused about aspect ratios) I'll post again.

In an MPEG2 file the Display Aspect Ratio (DAR) is flagged in the MPEG2 data. The relative frame dimensions (Storage Aspect Ratio, or SAR) don't have to match the DAR. For example, NTSC SVCD uses a 480x480 frame size but a 4:3 DAR, NTSC DVD uses a 720x480 frame size (3:2 SAR) for 4:3 and 16:9 DAR.

MPEG2 allows for the following DAR settings: 4:3, 16:9, 1:1 (square pixel, DAR = SAR) and (I believe) 2.11:1.

Some players ignore the DAR setting -- hence the wrong dimensions when you play an MPEG2 file. I'm not sure exactly how the DAR information is passed between filters in the DS filter graph. I suspect some filters may not handle the DAR.

[terrypin]

Great post, many thanks. I'll do nothing for the moment, as I seem to be in pretty good shape.

After your explanation, I even think I'm beginning to grasp roughly why these players are not displaying at the dimensions I'd expect. Some aspects are still puzzling me though. If you'll bear with me a bit longer I'll try to explain in detail.

After uploading that AVI file, a couple of my friends in rec.video.desktop rendered it and uploaded their MPEG-2 files. One of them
http://www.speedyshare.com/418517508.html
is identical to my own latest attempt, made in Womble. So I'll refer to that as 'mine'. The other, from Ken Maltby,
http://www.speedyshare.com/116165549.html
was made in TMPGEnc 4.0.

Both were DVD-ready MPEGs. Opening both in GSpot the only difference I could find in the sections 'Video Information' and 'Aspect Ratio Related' was that mine had a line 'Top Frame First', while Ken's had 'Bottom Frame First', whatever they mean! So I am puzzled why each display at different sizes in the 9 players I tested.

BS Player, IrfanView, MediaPlayer 2, NeroShowTime, PowerDVD, and Windows Media Player 10 all showed the same pattern: Ken's displayed at an AR of about 1.3, close to the original 4:3, while mine was just over 1.5.

Another 2 players, MediaPlayer Classic and KM Player displayed differently: Ken = 0.92, Mine = 1.05, both about 70% the above ratios, presumably due to some view setting that I haven't so far discovered.

I also included my TMPGEnc 3.0 XPress > Cut Edit view because Ken made his MPG in a similar program. (I don't have TMPGEnc 4.0.) Not surprisingly that displayed Ken's at 1.33. Mine was 1.5.

So none of the 8 players actually display an AR of 1.33. Ken's is very close at 1.3, but mine is significantly distorted.

My aim is to render the AVI (a video from a map program) to MPEG so that I can upload it, knowing it will be playable by others in that particular newsgroup discusson without distortion. Preferably by default in 'popular' players.

So, there are two puzzles:

1) Why the difference between the two files? In view of your comments, I would now have said it was something to do with the SAR/DAR issue, were it not for the fact that, as mentioned, these entries are identical.
FWIW, GSpot says:
Frame Width (pixels): 720
Frame Height (pixels): 576
Storage Aspect Ratio("SAR"): 1.250
Pixel Aspect Ratio ("PAR"): 1.422
Display Aspect Ratio ("DAR"): 1.778


2) Whether to meet my aim by

(a) finding some way of specifying the setup of the players (like WMP10, MPC, MP2, etc) so that they do display correctly, or

(b) Render the AVI differently in the first place, i.e. not DVD-compliant, to avoid the need for that.

--
Terry, East Grinstead, UK

[jagabo]

Assuming the 640x480 AVI file you originally uploaded is your source, and that it is square pixel (4:3 SAR and 4:3 DAR), the M2V file is encoded correctly. I'm not sure exactly how the encoder came up with the the MPG file but it didn't correctly understand that the source AVI was 4:3 SAR and DAR. So it resized the source frame incorrectly.

The actual 16:9 image in a 720x576 PAL DVD frame is encoded in the inner 704x576 pixels. 8 Pixels of padding are added to the left and right borders (in a commercial DVD these borders may include real picture data but they are not part of the 16:9 portion). If you take a 720x576 frame from the Test640x480.m2v, crop away 8 pixels from the left and right edges, then resize the remaining 704x576 frame to 1024x576 (16:9) you'll find that the original 4:3 image is in a 768x576 (4:3) portion of the frame -- within a pixel or two anyway.

I don't use TMPGEnc Express 3 or 4 but I have used their older TMPGenc Plus 2.5. When it imports source video you have the option of specifying the source aspect ratio. The correct choice is "1:1 (VGA)". You can also specify this later on if you missed it in the import wizard. I believe the version you have has a similar setting.

In general:

SAR * PAR = DAR

where:

SAR = Storage Aspect Ratio (the relative frame dimensions)
PAR = Pixel Aspet Ratio (the relative dimensions of individual pixels)
DAR = Display Aspect Ratio (the final displayed aspect ratio)

In a 16:9 PAL DVD the PAR is 16:11 and the frame size (of the 16:9 portion) is 704x576:

704   16   16
--- * -- = --
576   11    9

Obviously, you don't need to make the conversion calculations yourself, the software will make them for you. But you must make sure the software correctly identifies the source SAR and PAR, and that it's set up to output the correct DAR. The source SAR is easy for a program to identify, it's simply the frame dimensions. The PAR is more difficult because many AVI files don't include PAR information. And with most AVI file that do include PAR information it's private to the codec and may not be passed to the MPEG encoder.

MPEG's three main aspect ratios are a little confusing. Two of them specify the DAR (4:3 and 16:9) but the third specifies the PAR (1:1).

[terrypin]

Brilliant, thank you! I haven't taken it all in yet, but aim to study later.

It squares with this, from Ken, also just seen in this morning's post:
"Actually mine was made as a 4:3 image inside a 16:9 image, to maintain the aspect ratio and still provide for the 16:9 DVD format Terry mentioned as one of his objectives. It was made using a PAL DVD template and shows as PAL in GSpot. I am in NTSC land but most of the tools I use have the ability to create PAL formatted video.

I used the DVD format as that was the largest format Terry mentioned, and you can always compress a larger image to a smaller one with less impact than trying to do it the other way around."
(I'm not yet exactly sure how Ken made it, but intend to find out.)

On a very practical level, can you finally suggest how I should distribute such 640x480 AVIs, like the one under discussion, so that they are likely to be played without fuss at 4:3? And I suppose another requirement is that I want to use the raw 640x480 AVI, without having to fiddle with cropping/resizing etc.

I don't want to pre-empt your recommendation, but after much work late last night I'm personally coming to the conclusion that it's better to customise my settings in Womble. IOW, specify 640 x 480, rather than choosing the 720x576 DVD template. While that presumably means that my secondary objective (of including such MPGs in a DVD later) won't be met simultaneously, my experiments show the result gets played properly in all my players.

I've uploaded the result of encoding Test640x480.avi as Test640x480-CustomNotDVD.MPG:
http://www.speedyshare.com/608983664.html
(In Womble I specified it as 640 x 480, MPEG-2, 25 fps, CBR = 8000, PAR = 1.00)

Working down my list of players, these are the ARs it displayed on opening:

MediaPlayerClassic (my current MPG association): 1.33
BS Player: 1.33
IrfanView: 1.33
KM Player: 1.33
MediaPlayer2: 1.33
NeroShowTime: 1.33
PowerDVD: 1.33
VLC (but difficulty getting it to play): 1.33
WMP10: 1.33

Do you agree that seems the best approach please?

--
Terry, East Grinstead, UK

[jagabo]

You can make 640x480 square pixel MPG files like that and they should play properly. But then you'll have to make separate DVD compatible versions for DVD.

I had played around with the demo of Womble MPEG Video Wizard a while back and found that it is still on one of my computers (March 2006 update).

After a lot of fiddling around I was able to get it to output DVD compatible 4:3 MPG files that were very close to correct:

1) Import Clip
2) Drag clip to timeline
3) Right click on clip in timeline, go to Video and make sure Maintain Aspect Ratio is NOT selected!
4) Export -> Monitor -> Template, select DVD PAL
5) Export -> Video -> Expert -> PAR -> 3/4 (default was 9/16)
6) Export -> Monitor -> Start (saves MPG file)

The output MPG file had the source stretched to 720x480 rather than to 704x480 and padded with 8 pixels at the left and right sides. But that's probably close enough for you. This clip played with the correct DAR on everything except mplayer2.exe.

[terrypin]

That's great, thanks! Kind of you to take the trouble. I'll try that procedure asap.

Much appreciate your expert advice.

--
Terry, East Grinstead, UK

[jagabo]

Here's what Womble created:


untitled.mpg

[terrypin]

Thanks jagabo. Interesting. Unlike you, I got correct 4:3 playing on everything I tried except MPC, which gave about 1.27. (Maybe an accurate measurement would have been exactly 1.25?) MP2, your exception, gave me 4:3.

As a side issue I was also interested to find that, unlike my extensive tests yesterday, I had difficulty with several of my captures today. In fact today's behaviour was closer to what I've come to expect. Some issue concerning graphics resources or acceleration I gather? Maybe today my PC is creaking a bit more. I was pleasantly surprised yesterday that, for players that didn't have a capture tool built in (most of them) I was able to Prt Screen, paste to IrfanView, crop, and pop the dimensions into my on-screen calculator and hence get an AR figure. Today I had to improvise. I hit on a method I'm pleased with. IMO much neater than laying a ruler on the screen or getting out the digicam. I used one of several utilities I have that display the mouse cursor screen co-ordinates, and simply noted the numbers for two corners. After a couple of subtractions, bingo!

FWIW, here also is a summary of what each of the recent MPEG files gave in GSpot and VirtualDub MPEG-2



BTW, I'm not sure why VirtualDub MPEG-2 shows 'DAR = 2' etc? Unless that's meant to be a class code or something?

--
Terry, East Grinstead, UK

[jagabo]

Regarding the different aspect ratios on different computers -- it probably has to do what MPEG splitters and MPEG decoders are installed. Also, many players have DAR overide settings so you want to make sure they are all set to automatically adjust the DAR to that which is specified in the video.

The print-screen issues is easy. Most media players use the graphics card's video overlay feature. When using video overlay, the player window is a hole in the desktop through with the video, located elsewhere in video memory, can be seen. This has a lot of benefits but the drawback is that screen capture utilities see only a (usually black) hole. In the old days, video abilities weren't a part of the graphics card, it was a separate card. You would run a short cable from the graphics card to the video card then another cable from the video card to the monitor. The video card would look for the hole in the desktop and put the video in that hole with a chromakey process.

Only one program at a time can use video overlay. If you start up two players and hit print screen, when you paste into an editor you'll see a black window in one player and whatever video was playing in the other.

Sometimes a player doesn't shut down properly and video overlay isn't released. Usually when this happens you can find the windowless player with Task Manager and kill it, releasing video overlay for the next player.

I believe VirtualDubMpeg2 is showing you the actual flag value within the MPEG file. It is a field with only four defined values:

1 = 1:1 (square pixel, DAR = SAR)
2 = 4:3
3 = 16:9
4 = 2.211 (not used in dvd)