DirectShow Playback Guide

Introduction

Native DirectShow filter support was added to MC11.1 in December 2005 and has been improved drastically with MC12. DirectShow is a multimedia API released by Microsoft which became a standard component of Windows with Windows 98. It is essentially a replacement for the earlier Video for Windows technology. In Windows Vista this technology has evolved into the Windows Media Foundation, which performs similar services. It provides developers with a unified interface across different programming languages to allow their applications to render or record media files, using a filter based framework.

1. What is DirectShow? What is a DirectShow filter?

Media Center plays many media formats in DirectShow. This includes DVD and many video and audio files. DirectShow is a Microsoft technology for playing audio/video media on Windows computer.

DirectShow uses the concept of “Filter Graph”. A filter graph is built with individual “Filters”. A filter is a software component in DirectShow that will work with other components to render a media file, each filter processes audio/video data in a specific way to facilitate the playing of the media files. Filters have “pins” - points of connection between filters, both input pins and output pins. Pins are the means by which media data is passed from one filter to another filter. For example, the Input pin of the Haali Media Splitter will receive the data from the file, split it to it's component parts and then output those "streams" via it's output pins. FFDSHOW will then connect it's input pins to Haali's output pins and decode the video stream.

You can use the free GraphEdit utility from Microsoft to manually build filter graphs if you want to play around with how this works.

Filter Types

Generally speaking, there are three types of filters in terms of functionality: Source filters, transform filters, and renderer filters.

With most media files, it is important to understand the distinction between the file container format and the individual media stream formats (sometimes referred to as the codec of the file) "contained" inside the file. The container format is essentially the file you see on your hard drive (the AVI, MKV, MP4, OGM, or whatever) which is used to identify and interleave the different "stream" types that make up the actual media, including metadata tags, video streams, audio streams, subtitles, and other information.

Source Filters

A Source Filter is a component that loads a media file for playback used to decode the container file format and extract the actual audio, video, metadata, and subtitle streams (among other information). The simplest source filter simply loads a file and passes the stream contained in the file to downstream filters for further processing, but some source filter would act as a “splitter”, by parsing the data into separate audio and video streams and then pass them down to other filters. Examples of source filters are “File Source” which reads data from a file, “TV tuner filter” which tunes to a TV channel, and “DVD navigator filter” which reads data from a DVD disk. Another example is the Haali Media Splitter, which can decode MP4, AAC, and MKV files (among others).

Transform Filters

A transform filter is a filter that accepts media data from an upstream filter, process the data, and passes the data to a downstream filter. Therefore a transform filter must have both input and output pins (there may be more than one set of input and output pins on a given filter). An input pin connects to the output pin of an upstream filter (such as a source filter, which generally has only output pins). An output pin on a transform filter connects to an input pin of a downstream filter , such as a renderer filter, which has only input pins, or another transform filter. A decoder filter is a typical example of a transform filter.

Render Filters

A renderer filter is a component that renders a media stream, and is thus the last stage in DirectShow filter graph. For example an audio renderer is one that sends audio data to a sound card. A video renderer displays video to your computer screen.

Other Information

To play back a file properly via DirectShow you need both a Source Filter, specific to the file container type (which gives you access to the individual streams), and a Decoder Filter which actually decodes the video stream that the splitter hands it. Generally the Decoder Filters are categorized as Renderer Filters, but sometimes they are Transform Filters which pass data to more general purpose renderers). Generally you'll need one Decoder filter to process each "stream type" that comes out of the Source Filter (though many handle more than one type of stream, like FFDSHOW). Examples of these are the FFDSHOW MPEG-4 Video Decoder (ffdshow.ax), XviD Video Decoder (xvid.ax), the Microsoft MPEG Audio Decoder (quartz.dll), and DirectVobSub (VSFilter.dll).

Sometimes these lines blur, when a particular filter can act as both a splitter and a decoder filter (such as FFDSHOW).

How DirectShow Playback Works in MC

MC supports a number of audio file types natively. When you play back a MP3 file, for example, MC uses it's own internal high-quality filters to split and decode the file and send it to the appropriate output device (sound card). When you attempt to play a file back in MC that it doesn't support natively, MC tries a number of different things to get the file to play. The first step is to attempt to render the file using DirectShow.

By default, if you haven't modified the DirectShow playback configuration options in MC, and you play a file back, it simply asks Windows to build the regular DirectShow graph. This works the same as Windows Media Player and any other DirectShow player does when playing back a file.

The default graph is built based on two factors: a) each individual filter "tells" DirectShow what kinds of media streams it is able to render, and b) DirectShow assigns (or more precisely, the filters assign to themselves when you install them) a priority number called its "merit score".

When you play a file, DirectShow attempts to build a chain of filters capable of decoding the content based on these two pieces of information. It tries filters matching the stream type, in the order of which filter has the highest priority first. If the "render" fails, then it tries the next highest priority set, and so on and so forth until it runs out of options or succeeds. Just because it "works" doesn't mean it's necessarily finding the "best" filter graph.

MC's DirectShow Playback settings dialog overrides the priority part of this sequence of events. If you select one or more of those filters, it overrides the normal merit score system (perhaps by temporarily elevating them to the highest possible Merit -- I'm not sure of the details of this mechanism). So, you can force it to "try" to use a different filter to play a file back, but you can't force it to use one or fail outright. If that graph fails (the output pins can't connect to the input pins to build a complete render graph) then it either ignores certain selected filters, or it fails over completely to the default graph. (MC's DirectShow Playback Settings dialog provides essentially identical functionality to ZoomPlayer's "Smart Play" feature.)

I've simplified this a bit for the sake of explanation, but that's the general idea of what happens when you try to play a file back via DirectShow.

2. What version of DirectX do I need?

In order to play media using DirectShow, you must have Microsoft DirectX installed. We recommend DirectX 9.0c to take advantage of features that are available only in late versions. This version is already installed on Windows XP and later operating systems, and you do not need to do anything in most cases. For earlier versions of Windows operating system, we recommend you download it from Microsoft website and install it.

3. Why do I need to get DirectShow filters?

In order to play media files in DirectShow, one must have DirectShow filters that can handle the media types to be played. DirectShow comes with some of the filters that are needed, for example video and audio renderers. DirectShow, however, does not include all filters that are needed. You must make sure you have needed filters for the file types you want to play. DirectShow filters come from a variety of sources. We do not, and can not, include all filters that are needed in Media Center‘s installation. In most cases you will need to install decoder filters from other sources. For example in order to play DVD on your computer you must have DVD capable MPEG-2 video decoder, and audio decoder(s) that are capable of decoding MPEG-2 audio and/or AC3 audio formats.

Some computers do come with certain filters installed by the computer vendor. However, the filters preinstalled may not be top-notch filters. In such case it is to your advantage to find and install better filters..

4. How do I install DirectShow filters?

It depends on the filter. Some filters come with an installation program. You just need to execute the program, and the installation wizard will guide you through the process. Most filter packs are installed this way.

Not all filters come with an installation wizard. Instead they are just one or more files with file extension .ax or .dll, often contained in an archival file (ZIP or RAR). In such a case, you can first extract the file(s) into a folder (any folder is fine, for example “C:\Program Files\DirectShow Filters\“ would be a good choice). Then register the filter using Windows program Regsvr32.exe. This program exists on every Windows computer. For example, if you downloaded a filter whose file name is NewFilter.ax, and you place the file in “C:\Program Files\DirectShow Filters\“, you can register it by clicking Start button and choose “Run…” command and enter the following line (including quotes):

regsvr32.exe "C:\Program Files\DirectShow Filters\newfilter.ax"

and click OK. A dialog box should pop up saying "DLLRegisterServer in C:\Program Files\DirectShow Filters\newfilter.ax succeeded", indicating that the filter is now registered with the system.

Some filters may come with two versions of them, a Unicode version and a non-Unicode verion. You should register the Unicode version as Media Center supports Unicode.

You can also unregister a filter, in case you decide you no longer need the filter, by using the command line parameter /U. For example to unregister the filter registered in the above example, you issue this command:

regsvr32.exe /U "C:\Program Files\DirectShow Filters\newfilter.ax"

You will also get a confirmation saying “DllUnRegisterServer in C:\Program Files\DirectShow Filters\newfilter.ax succeeded.”

5. What filters do I need and where do I get them?

The answer depends on what media format you want to play. In general you will need decoder filters and, in many cases, you will also need splitter filters. You can obtain commercial filters from various vendors. You can also get free, open source, filters. In this guide we will tell you about some free filters.

Before getting to individual media formats, it is a good idea introducing/recommending the following multi-filter pack and multi-format decoders:

CCCP - Combined Community Codec Pack

CCCP Home Page

This is a great multiple-filter pack that provides filters for playback of most media formats, including DVD. CCCP includes FFDShow (see below), which can be used to decode a large number of media formats, MPV video decoder which decodes DVD and other MPEG-2 video, and Haali Media Splitter that can be used for playback of many media types.

This is probably the single simplest method to get the vast majority of file types to play back properly and reliably. There are a few file types that CCCP does not support out of the box, including Quicktime, RealMedia, and FLV video (though it tries at FLV). Adding support for these file types is described below, though the CCCP Project site has much more information on this topic.

Make sure you read the instructions before installing CCCP. As a general rule, you should uninstall any previously installed codec packs, as different codec packs often conflict with each other. You should also uninstall previously installed individual filters that CCCP includes, such as FFDShow, Haali Media Splitter. This way you will be sure that CCCP can install and configure the filters properly.

Additionally, when installing CCCP, make sure you uncheck the option to install FLV Splitter. The version of FLV splitter included with CCCP does not work well. See "FLV" below.

Alternative Filters

While CCCP is the easiest way to get your system working, there are alternatives of course. Below is a list of some of the big alternatives. Many of these are actually components of CCCP, but can all be obtained and used separately. The list below contains both Splitter Filters and Decoder Filters.

FFDSHOW

FFDShow is a Multi-Format Decoder filter with major Post Processing capabilities. It is essentially a windows DirectShow Filter version of the FFMPEG Codec Project libraries, which are used to support MPEG-2/4 video and audio decoding by many non-DirectShow, cross-platform, applications (such as VLC). Installing FFDSHOW on your system gives you all the power of the FFMPEG codecs in all of the DirectShow player applications installed on your system (including MC of course)!

FFDSHOW acts as a sort of "Swiss Army Knife" filter. It acts as both a Splitter Filter and a Decoder Filter (both Audio and Video). It can be used to decode many video and audio formats beyond it's "original" focus of MPEG-2/4 file types, including: MPEG-4 ASP (Xvid, 3ivX, and DivX) and AVC (H264 and VC1), MPEG-2 (DVD), MPEG-1, H263, VP6 (Flash Video), MP3, AAC, Dolby AC3, FLAC, WMA, and Vorbis among many others. It can also be used to route certain video types through other filters (such as DScaler) for post-processing, and perform many post processing effects itself (de-interlacing, grain removal, noise reduction, sharpening, etc).

CCCP includes FFDShow (so there is no need to install it separately if you use CCCP). If you choose not to install CCCP, you should consider installing FFDShow.

It can be difficult for users to find a good version as there are too many different versions/builds out there.

A fairly stable but older version can be found here (ffdshow-20051129.exe)

People have had good experience with Celtic Druid's builds, which you can find here.

Even newer versions can be found at FFDShow tryouts.

Very good FFDshow primer on AVS: AVS FFDshow Config Primer

Starting with MC 12.0.266, MC now supports using FFDSHOW as a post processing filter for DVD and TV Tuner playback, which provides some very exciting possibilities.

DVD

For DVD playback, you need DVD capable MPEG-2 video decoder and MPEG-2 / AC3 audio decoder. These filters may or may not already exist on your computer. Some computers come with filters for DVD; some do not. Filters may also come with installation of some third-party software. If you do not already have the needed filters, you may need to install them. Commercial decoders are available from various vendors. Free decoders are available and described below.

CCCP can be used for DVD playback (see above).

Alternatively you can try these filters:

Video decoders:

DScaler 5. This is still in alpha. Therefore expect to have some problems with it. I have had only one problem though. It is related to DVD menus. I experience menu problem only with one of several DVD movies I played.

Generally DScaler can be used for vastly improved deinterlacing and resizing support, and it's quality is "considered" the best. It can be difficult to get it set up properly.

Gabest Universal Open Source MPEG Video Decoder

Older versions of FFDShow video decoder do not work well with DVD (even though it has user interface to turn on DVD decoding capability). Newer versions maybe able to decode DVD properly. However, because there are still some (relatively minor) issues with DVD decode support in FFDSHOW, CCCP still uses the Gabest Decoders instead, which work quite reliably.

Audio decoders:

FFDShow Audio decoder works well with DVD.

DScaler 5 (DScaler 5 includes both an audio decoder and a video decoder).

AC3Filter is another good option for decoding AC3 and DTS tracks.

[Be sure to read this FAQ] if you are interested in full support for DTS WAV playback.

MPEG-4 Container Family mp4 / m4a / m4v

In order to play these types of files in DirectShow engine, you will need not only decoder filters but also splitter filters. Generally FFDSHOW would be the best decoder filter for most MPEG-4 video stream types, but you do need a separate application to "split" the MP4 container format to feed FFDSHOW the stream data.

Splitters:

You can use Haali Splitter (which is used in CCCP), or MP4 splitter.

3ivx has a filter pack that includes all filters (splitter and decoders) needed for mp4 type. It is however not free.

MKV

Matroska is a modern, extensible open standard A/V container. Matroska is typically found as .MKV files (matroska video) or .MKA files (matroska audio). CCCP is the official codec set for Matroska files, and it is the recommended way to handle these file types.

There are other options of course, Haali Splitter will handle decoding MKV files on it's own.

FLV

FLV, flash video, is a format widely used for streaming. For example Google video and YouTube use this format. This format should play correctly in Media Center without user actions. However, if you do have problem playing them, you need to make sure the following filters are properly installed and configured.

FFDShow (see above).

You need to configure it so it will decode FLV video. Media Center should configure it for you automatically, but here is how you can do it manually:

Start -> All Programs -> FFDShow (or Combined Community Codec Pack) -> FFDShow Video Decoder Configuration. Choose "Codecs" from the top of the left panel. On the right panel, find FLV1 in the first column ("Format"), and change the value in the second column ("Decoder") from "disabled" to "libavcodec". Click OK.

FLV Splitter

Download and unzip it. Register it.

Note: The latest CCCP also includes a version of FLVsplitter that does not work with Google/YouTube videos. You should use the version linked here (built by Celtic Druid), which, in addition to being able to play FLV1 videos from Google/YouTube when used with FFDShow, also includes an FLV Video Decoder filter which decodes FLV4 format (FFDShow decodes FLV1).