MP4S M4S2: Microsoft ISO MPEG-4 versions 1 and 1.1

posted in Solutions

See next post below for M4S2 in AVI

Quick Solutions:
1. (which package you download depends on your version of windows and windows media player)
2. Update your version of Windows Media Player to 7.1 (MP4S) or 9 (M4S2) or higher (link good for Mac users as well*)
* Windows Media Player for the Mac will only decode ASF/WMV files.
Those codecs should also be available as automatic downloads using Windows Media Player if one is connected to the internet.

More info:
MP4S: Microsoft ISO MPEG-4 version 1
M4S2: Microsoft ISO MPEG-4 version 1.1
These releases are likely Microsoft’s attempt at ISO compliance (following the MPG4, MP42, and MP43 fiasco). According to the ASF Specifications, the codecs are to be found in Microsoft’s own Windows Media container (extension asf/wmv). In practice, I have never seen an asf/wmv file with fourcc M4S2. I have seen many digital camera samples with MP4S in asf/wmv and M4S2 in AVI, but not any other combination.
Windows Media Encoder 7 allows encoding (of asf/wmv files obviously) in MP4S. Windows Media Encoder 9 allowed MP4S encoding up until Windows XP Service Pack 1 (it’s in the list of codecs choices if CBR (constant bitrate) is picked for video). In Service Pack 2, the ability to encode in MP4S was removed. M4S2 encoding doesn’t appear to ever have been offered.

Keywords: MP4S, M4S2, Microsoft ISO MPEG-4 reply


M4S2 in AVI

Summary: First part of this post deals with playback on the Mac, second part with editing in VirtualDub on PC

Some digital cameras and camcorders produce AVI videos with fourcc M4S2. Playback for PC users is without problems (any of the links in the previous post will work), but it won’t work for Mac users, since Windows Media Player for the Mac will only decode wmv/asf files, not avi files.
a. Canon came up with a QuickTime plugin for M4S2 on their site here: (works with Mac OS 9 and X)
b. Casio also released a QuickTime component for M4S2 importing:
c. Some Japanese guy by the name of emonkid wrote an open source plugin (both for Windows and the Mac - but only OS X) using ffmpeg libraries. His plugin is available for download here

Another problem with M4S2 in an AVI container is Microsoft’s decoder is DirectShow-only, so VfW (Video for Windows) utilities (like VirtualDub) will not be able to open it. The specific message in VirtualDub will say
"'Couldn’t locate decompressor for format 'M4S2'. VirtualDub requires a Video for Windows (VFW) compatible codec to decompress video. DirectShow codecs, such as those used by Windows Media Player, are not suitable."

These workarounds uses the fact M4S2 is one of many flavors of MPEG-4 part 2 (others being DivX, Xvid, 3ivx, etc.)
Workaround 1 - In VirtualDub you can open a file while “simulating” it as having a different fourcc, without hard-writing the fourcc into the file. In this case, we make it act as if it were a DivX or Xvid file. Click file, open video file, then check the box 'ask for extended options after this dialog' then pick your file. On the following window check the box 'force video format fourcc to' and type in a fourcc for some other flavor of MPEG-4 (DIVX DX50 XVID 3IV2 or whatever else you think will work - obviously you have to have the corresponding decoder). This method may fail to decode the first frame (all black screen).
Workaround 2 - Another suggested solution for working with M4S2 AVI files in VirtualDub uses ffdshow-tryouts. Be sure to check “VFW interface” and “Application plugins: VirtualDub” during install. If you don’t need any other codecs except M4S2 VfW decoding for VirtualDub, during install, uncheck everything except “Generic MPEG-4 decoding”. When done installing, go to your start menu, (all) programs, ffdshow, VFW configuration. Click on the decoder tab. Click on Codecs in the left column. The row “Other MPEG4” should have anything EXCEPT disabled (you can use whichever decoder you like... xvid or libavcodec - and switch if one doesn’t work). As you can see to the right of that Supported FOURCC should have M4S2 listed. At this point, AVI files with fourcc M4S2 should open just fine in VirtualDub.

Here are some known camera and camcorder models that produce AVI files with fourcc M4S2:
Casio Exilim family: EX-P505, EX-S500, EX-S600, EX-S770, EX-Z750, EX-Z850
Pentax Optio family: S5z
Canon Optura family: Xi, 300
-- fills to this list are welcome --

Keywords: M4S2, AVI reply


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