Directshow Video Code Much Simpler
Net, to make your project code much simpler or provide a lot of additional features. Net and Video Capture SDK. Virtual Camera SDK can be used as an independent product in DirectShow applications or together with our SDK’s Video Edit SDK. VisioForge SDK’s integration.
It can render or record media files on-demand by the user or developer. Media Types Supported by the LEAD MPEG2 MultiplexerMicrosoft DirectShow is an extensible, filter-based framework, based on the Microsoft Windows Component Object Model (COM), that provides a common interface for media across many of Microsoft's programming languages. ITU-T H.265/MPEG-H Part 2, HEVC (ISO/IEC 23008-2) Name FourCC Guid LAVID MKVID Notes H.265, Main/Main Still Picture profile: 0x43564548 HEVCffdshow is DirectShow and VFW codec for decoding/encoding many video and audio formats, including DivX and XviD movies using libavcodec, xvid and other.Table 1. 8-bit per channel planar YUV 4:2:0 video. Containers (38) Major types (34) Formats (1017). Required to make the camera work with DirectShow do not register with Windows correctly.Where does the LEADTOOLS Multimedia SDK Fit In?Media Foundation and DirectShow Media Types.
Directshow Video How To Manage Multimedia
Each step, or stage in the processing of the data, is called a filter. DirectShow's most notable competitor is Apple Computer's QuickTime framework.DirectShow divides multimedia task processing such as video playback into a set of steps. DirectShow development tools and documentation are distributed as part of the Microsoft Platform SDK.Most video-related Windows applications, such as Microsoft's Windows Media Player, Winamp, and Windows Movie Maker, use DirectShow to manage multimedia content.
This is usually the first filter in the graph. These handle much of the creation, registration, and connection logic for the filter.Since the entire concept of rendering, converting, and capturing files in DirectShow is based on filters and filter graphs, it is important to understand the role of each filter.Source filter. Developers can add custom effects or other filters at any stage in the graph, then render the results to a file, URL, or camera.DirectShow Base Classes, a set of C++ classes provided in the DirectShow SDK, are used to build most filters. Filters can be connected in different ways for different tasks to build a filter graph that lists all necessary filters to perform a specific task.
It is usually connected to the source filter. This filter is responsible for splitting the media streams. The data can come from a file on disk, a network, or any other method.Demulitplexer.
These filters are used to actually render data. For example, the video decoder input might be a compressed video stream such as MPEG2, and the output could be raw video data.Renderer. Therefore, they are usually connected to the demultiplexer output. They do not demultiplex, so data should be demultiplexed before it is passed to the decoder. These filters handle the actual decoding or decompression.
The input is usually uncompressed audio or video data, and the output is the compressed version of the same data.Multiplexer. These filters are used to compress data, audio or video. The input of the renderer is usually uncompressed data coming from the decoder.Audio/Video Encoder. For example, when playing a media file with both audio and video, a video renderer would handle displaying the video on the screen, and an audio renderer would handle directing the audio data to the sound device.
They can handle writing the data to disk to create a media file, or they can send the data to some other location, such as over a network.Video/Audio Processor. These filters are usually the last filters in the graph. The output is a single stream containing both video and audio data.Sink Filter. Input is usually compressed data from an audio/video encoder.
Media Types Supported by the LEAD MPEG2 Multiplexer MediaFORMAT_WaveFormatEx (WAVE_FORMAT_MPEGLAYER3 format)The following figures illustrate basic filter graphs for capture, conversion, and playback:For the filter graph to use filters automatically, the filters need to be registered in a separate DirectShow registry entry, as well as being registered with COM. Attempting to connect any media type other than those listed to the input of the LEAD MPEG2 Multiplexer results in the connection being refused.Table 1. This is why it is important to know what media types each filter supports.For example, the following table lists media types supported by the LEAD MPEG2 Multiplexer. An MPEG2 Decoder will only decode MPEG2 video, and an MPEG2 Demultiplexer will only accept as inputs a stream containing MPEG2 video and certain types of audio related to MPEG2.If you try to connect filters that do not agree on data types, the connection is usually refused and the graph will not run. The same goes for decoding and demultiplexing. Most likely, the MPEG2 Encoder will only create MPEG2 compressed data and the MPEG2 Multiplexer will only accept MPEG2 video and certain types of audio related to MPEG2 as inputs.
Under the merit system, implementations often compete with one another by registering themselves with increasingly elevated priority.Thus, although DirectShow is capable of dynamically building a graph to render a given media type, it becomes difficult for developers to rely on this functionality when the resulting filter graph is variable. " Codec hell" ensues when multiple DirectShow filters, all used for encoding or decoding the same media type, exist on a given computer. If multiple MPEG2 decoders exist on the machine, the decoder with the highest value in the registry will be used.Many companies now develop codecs in the form of DirectShow filters, resulting in the presence of several filters that can decode the same media type. For example, to decompress MPEG2 data, you need an MPEG2 decoder. The actual properties or quality of a filter have nothing to do with its merit. The "merit" of each filter is determined by a value stored in the registry—and that value is determined by the creator of the filter.
Options include controlling the TV tuner, and setting many common device properties such as capture size, color space, and frame rate.However, actual control over the device is limited by what the manufacturer of that device has exposed in the DirectShow driver, and what has been implemented in the device itself. Developers often resort to manually building filter graphs to be certain of their contents, crippling one of DirectShow's more appealing features.DirectShow also has many interfaces for capturing from and controlling many types of webcams, TV tuners, and other devices that have a DirectShow driver. This can result in a support nightmare for developers and businesses.
But that flexibility has a cost: complexity.LEAD's solution—the LEADTOOLS Multimedia SDK—handles the complexity "under the hood," but exposes Multimedia functionality to the developer through dozens of easy-to-use interfaces.Three of these interfaces handle the most common tasks: ltmmCapture, ltmmPlay and ltmmConvert. Its greatest strength is its ability to "get under the hood" to connect filters programmatically, create custom filters, etc. One device may allow you to change the frame rate, while another may not.The problem with DirectShow is that its greatest strength is also its greatest weakness.
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