VC-1 Advanced Profile/Levels Problems [Archive]

anrque

26th February 2007, 19:49

I've looked through the forum and not found this posted yet, but has anyone working with VC-1 found that when authoring files in Windows Media Encoder or 3rd party apps like Vegas, files matching the printed advance profile/level combinations from Micosoft's website are not corect?

http://www.microsoft.com/windows/windowsmedia/forpros/events/NAB2005/VC-1.aspx

I've compressed a number of files that have frame sizes or bitrates well below the MAXIMUM listed for a given level number only to find out after the compression job is done that the AP@L1 file I was making is showing up as AP@L2. (I'm using a hex editor to get this info from the header BTW)

Am I doing something wrong here or making an assumption during my encodes that is sending me down the wrong path? Thanks.

anrque

27th February 2007, 22:10

Okay, I just tried this again with another clip to verify. My source is an uncompressed AVI 480P running at 59.94fps. It's 720x480 and pixels are non-square NTSC standard. According to the AP@Levels table at Microsoft and wikipedia I should be able to compress this using the advance profile codec up to 20mb/s to get a level 2 file. If I use CBR, I can get 13.5mb/s before the wmv header indicates level 3. For bit rate VBR I've already gone as low as 7mb/s and the header info still indicates level 3. Is there a switch that I'm missing somewhere? This is really odd.

Inventive Software

28th February 2007, 02:12

Setting a "Max bitrate" in 2-pass VBR should make it compliant.... I can't say more cause I don't use Windows Media Encoder (WME).

anrque

1st March 2007, 18:45

I've definately tried this with no success. AP@L2 states a 480P video can be upto 20MB/s. Even with 20 set as the maximum the resulting video is identified as level 3 in the header. I am having no luck here. You wouldn't think that making these compliant to a given level would be that difficult.

zambelli

2nd March 2007, 03:30

I've definately tried this with no success. AP@L2 states a 480P video can be upto 20MB/s. Even with 20 set as the maximum the resulting video is identified as level 3 in the header. I am having no luck here. You wouldn't think that making these compliant to a given level would be that difficult.
Anrque, thanks for pointing this out. I will look into it more closely and check if the codec is not following the VC-1 spec.