How is sequence header aspect ratio set?

[BGane]

I have been using DVD2SVCD to produce MPEG1 video files from DVD for playback in computer-based media players. The encoder that I use is TMPGENC 2.59. Everything is working fine, except for one problem:

The MPG files that are being generated by TMPGENC, with the settings generated by DVD2SVCD (is this the .TPR file?), have an aspect ratio byte in the MPEG file sequence header set to "2", and this is causing a problem for me, but only with Windows Media Player. Other players seem to display the videos just fine.

The width and height fields are set as I wish for the VCD standard at 352 x 240. However, an aspect ratio of "2", from my read of the ISO/IEC standard, implies a ratio of .6735. If I look at the table, and from advice that I have been given elsewhere, the ratio SHOULD be set as "C", which implies a ratio of 1.125.

Now, in other players (ie. Winamp3, Media Jukebox, PowerDVD) it would appear that they ignore the aspect ratio byte. The videos play with a small, but acceptable border top and bottom. However, WMP9, it would appear, divides the width setting by the implied aspect ratio. Hence the decoder in WMP9 is coming up with a display width of 522 (352 / .6735), and the vids are playing as if they were encoded 2.35:1 (or worse). If I hex edit the MPG file to replace the sequence header aspect ratios with "C", then the vids play properly in WMP. Since the other players apparently ignore the field, they remain unaffected.

Now, I can continue to edit my files to get the proper setting, but what I would like to know is - what field could I edit in the DVD2SVCD settings (ini file?) to cause the aspect ratio to be set as I need it for VCD 525 line 4:3 aspect ratio (ie. to force a "C" setting in TMPGENC encoding)?

[markrb]

For VCD, SVCD and DVD playback in short WMP just sucks. You are much better off with a real player like WinDVD or PowerDVD. It has also been shown that WMP can have issues with sync as well, where these other player don't.

Mark

[BGane]

Agreed Mark. I use WMP for primarily for previewing results, and for casual playback. I don't use it for professional purposes. Still - does the Microsoft video support fellow have a point? Shouldn't the aspect ratio byte be set to "C" for a VCD? He sent me the table from the ISO doc, and sure looks as if it should be.

When TMPGENC is invoked by DVD2SVCD, I noticed that I can have a look at the settings without interfering with the encoding. If I look at the video tab, it would appear that the setting is for "VGA 1:1", and not "525 line 4:3". Normally, when I run TMPGENC manually, I select 525 line 4:3, and it creates a proper MPEG file for me. That's why I was enquiring how to change the setup that is created by DVD2SVCD for TMPGENC.

[BGane]

Incidentally, just to qualify my remarks above, I have selected "4:3 aspect ratio" on the DVD2SVCD panel. Yet, despite this setting, it seems that TMPGENC is invoked, and the video tab shows "VGA 1:1" as the desired aspect. This setting is coming from the TPR file, which is set up by DVD2SVCD. I don't see a specific setting in the DVD2SVCD.INI file that I can change to make the TPR file what I want. Is there an INI file entry that I can add that will cause TMPGENC to be set up so that it explicitly sets the aspect ratio as 4:3?

[onesoul]

For curiosity does this affect the image aspect played at a stand alone dvd player?

[BGane]

Mark or dvd2svcd: Is there no comment on why you are generating non standard VCDs?