The codec status table is a complete list of all supported codecs, regenerated daily. Some binary codecs for use with MPlayer are available in the download section of our homepage. If you have a Win32 codec which is not supported yet, please read the codec importing HOWTO and help us add support for it. This is the default decoder used for files with AC-3 audio. The AC-3 decoder can create audio output mixes for 2, 4, or 6 speakers. When configured for 6 speakers, this decoder provides separate output of all the AC-3 channels to the sound driver, allowing for full "surround sound" experience without the external AC-3 decoder required to use the hwac3 codec. Use the -channels option to select the number of output channels. Use -channels 2 for a stereo downmix. For a 4 channel downmix (Left Front, Right Front, Left Surround and Right Surround outputs), use -channels 4. In this case, any center channel will be mixed equally to the front channels. -channels 6 will output all the AC-3 channels as they are encoded - in the order Left, Right, Left Surround, Right Surround, Center and LFE. The default number of output channels is 2. To use more than 2 output channels, you will need to use OSS, and have a sound card that supports the appropriate number of output channels via the SNDCTL_DSP_CHANNELS ioctl. An example of a suitable driver is emu10k1 (used by Soundblaster Live! cards) from August 2001 or newer (ALSA CVS is also supposed to work). You need an AC-3 capable sound card, with digital out (S/PDIF). The card's driver must properly support the AFMT_AC3 format (C-Media does). Connect your AC-3 decoder to the S/PDIF output, and use the -ac hwac3 option. It is experimental but known to work with C-Media cards and Soundblaster Live! + ALSA (but not OSS) drivers and DXR3/Hollywood+ MPEG decoder cards. This codec (selected by -ac hwmpa) passes through MPEG audio packets to hardware decoders, such as the ones found in full-featured DVB cards and DXR2 adapters. Don't use it in combination with any other audio output device (such as OSS and ALSA) that isn't able to decode it (you will hear only white noise). VFW (Video for Windows) is the old Video API for Windows. Its codecs have the .DLL or (rarely) .DRV extension. If MPlayer fails at playing your AVI with this kind of message: UNKNOWN video codec: HFYU (0x55594648) It means your AVI is encoded with a codec which has the HFYU fourcc (HFYU = HuffYUV codec, DIV3 = DivX Low Motion, etc.). Now that you know this, you have to find out which DLL Windows loads in order to play this file. In our case, the system.ini contains this information in a line that reads: VIDC.HFYU=huffyuv.dll So you need the huffyuv.dll file. Note that the audio codecs are specified by the MSACM prefix: msacm.l3acm=L3codeca.acm This is the MP3 codec. Now that you have all the necessary information (fourcc, codec file, sample AVI), submit your codec support request by mail, and upload these files to the FTP site: ftp://upload.mplayerhq.hu/MPlayer/incoming/<codecname>/ On Windows NT/2000/XP search for this info in the registry, e.g. search for "VIDC.HFYU". To find out how to do this, look at the old DirectShow method below. DirectShow is the newer Video API, which is even worse than its predecessor. Things are harder with DirectShow, since system.ini does not contain the needed information, instead it is stored in the registry and we need the GUID of the codec. Using Microsoft GraphEdit (fast) Get GraphEdit from either DirectX SDK or doom9. Start graphedit.exe. From the menu select Graph Insert Filters. Expand item DirectShow Filters. Select the right codec name and expand item. In the entry DisplayName look at the text in winged brackets after the backslash and write it down (five dash-delimited blocks, the GUID). The codec binary is the file specified in the Filename entry. If there is no Filename and DisplayName contains something like device:dmo, then it is a DMO-Codec. Take a deep breath and start searching the registry... Start regedit. Press CtrlF, disable the first two checkboxes, and enable the third. Type in the fourcc of the codec (e.g. TM20). You should see a field which contains the path and the filename (e.g. C:\WINDOWS\SYSTEM\TM20DEC.AX). Now that you have the file, we need the GUID. Try searching again, but now search for the codec's name, not the fourcc. Its name can be acquired when Media Player is playing the file, by checking File Properties Advanced. If not, you are out of luck. Try guessing (e.g. search for TrueMotion). If the GUID is found you should see a FriendlyName and a CLSID field. Write down the 16 byte CLSID, this is the GUID we need. If searching fails, try enabling all the checkboxes. You may have false hits, but you may get lucky... Now that you have all the necessary information (fourcc, GUID, codec file, sample AVI), submit your codec support request by mail, and upload these files to the FTP site: ftp://upload.mplayerhq.hu/MPlayer/incoming/<codecname>/ If you want to add a codec yourself, read DOCS/tech/codecs.conf.txt.