Media Multiplexing in .NET

Create QR in .NET Media Multiplexing
2.2 Media Multiplexing
QR-Code Decoder In VS .NET
Using Barcode Control SDK for Visual Studio .NET Control to generate, create, read, scan barcode image in Visual Studio .NET applications.
Figure 2.3 depicts the typical structure of an MPEG encoder. The encoder in fact comprises two independent encoders, one for audio stream and one for video stream. These two media streams are rst encoded independently to produce the corresponding compressed audio and compressed video streams, and then multiplexed together by the system encoder to a system stream. The multiplexer serves the important function of adding presentation time stamps to the
QR Code JIS X 0510 Maker In .NET
Using Barcode generator for Visual Studio .NET Control to generate, create QR Code image in .NET applications.
Media Compression
Reading QR Code JIS X 0510 In VS .NET
Using Barcode scanner for Visual Studio .NET Control to read, scan read, scan image in .NET framework applications.
audio bit-stream (audio packets) Audio Input Audio Encoder Multiplexer (System Encoder) Video Input Video Encoder video bit-stream (video packets) Decoding Time Stamp (DTS) Added Presentation Time Stamp (PTS) Added System bit-stream (system packs)
Barcode Generation In .NET Framework
Using Barcode maker for .NET Control to generate, create barcode image in .NET framework applications.
Figure 2.3 The encoding process in a typical MPEG media encoder
Barcode Scanner In .NET Framework
Using Barcode reader for Visual Studio .NET Control to read, scan read, scan image in VS .NET applications.
system stream and multiplexes the audio and video data streams according to their timing correlations. This system stream can then be delivered over the network to the clients for playback, where the reverse decoding process will occur, i.e., it rst demultiplexes the system stream into separate audio and video streams, and then decompresses them for synchronized playback. In media streaming, the media multiplexer can reduce the complexity of the media server. In fact, the media server can simply treat the multiplexed system stream as a binary bit stream encoded at a combined system stream bit-rate, irrespective of the detail compression algorithms and data format employed. This is a signi cant advantage as it decouples the media server implementation from the media compression standard employed. In other words, we can reuse without modi cation the same media server to stream media data compressed using new compression algorithms when they become available. By the same token, we can also stream multiple types of media streams encoded with different compression standards using the same media server, thereby reducing cost and operational complexity. Alternatively, a media server can also send the compressed audio and compressed video data streams separately over the network (cf. 6), bypassing the MPEG multiplexer altogether. In this case, the media server will then need to send the data streams in such a way that audio and video data will arrive in time for synchronized playback. This usually requires the media server not only to perform I/O, but also to inspect and interpret the contents of the media streams to extract timing information to schedule data transmissions, and to construct packet headers with presentation timing information. In this model the media server implementation will be coupled to the media compression standards employed, and it will also consume more processor cycles in processing the media data. Nevertheless, this approach does give the media server more control over the data delivery process. For example, the service provider could produce multiple versions of the media streams at different bit-rates to cater for varying network bandwidth availability. In this case the media server can begin streaming the highest quality media streams to a client, and then dynamically switch to a lower quality (and thus lower bit-rate) media stream if the available network bandwidth drops below a threshold to ensure continuous media playback. Network bandwidth variations are common in the current Internet and thus the capability to dynamically adapt the video content to avoid playback interruptions is an important and useful feature to the end users (cf. Section 2.5).
QR Code Drawer In C#
Using Barcode creation for .NET framework Control to generate, create QR Code image in .NET framework applications.
Scalable Continuous Media Streaming Systems
Encoding QR Code JIS X 0510 In VS .NET
Using Barcode generator for ASP.NET Control to generate, create QR image in ASP.NET applications.
2.3 Temporal Dependencies in Compressed Video
Make QR Code In VB.NET
Using Barcode encoder for Visual Studio .NET Control to generate, create Quick Response Code image in .NET framework applications.
Video encoders typically exploit three types of redundancies to reduce the compressed video bit-rate, namely, spatial redundancy, temporal redundancy, and entropy. Spatial redundancy refers to the correlation between pixels within the same video frame. This is also known as intra-frame coding as only pixels within the same video frame are used in the encoding process. The resultant encoded video frame, commonly called the I frame, can be decoded independently. Temporal dependency refers to correlations between adjacent frames. As the video captures a snapshot of a video scene periodically at, say, 25 to 30 fps, adjacent frames will likely contain very similar visual objects, often with some displacements due to motion of the objects or the camera. Thus, the encoder can exploit this correlation by predicting a video frame from the neighboring frames. In MPEG, for example, this is done through the use of predictive frames (P frames) and bi-directional predictive frames (B frames) as shown in Figure 2.4. Speci cally, beginning with an intra-coded I frame, the encoder will rst predict the P frame using a process called motion estimation. In motion estimation the encoder will search for similar blocks of pixels in the I frame and the to-be-encoded P frame. After the search is completed, only the displacement of the block (due to motion) and the prediction errors are encoded to form the data for the P frame. Thus, P frames can be encoded using substantially fewer bits than an I frame. This encoded P frame will then be used to predict the next P frame and so on until another I frame is introduced. In addition to P frames, a number of B frames are also introduced between a pair of anchor frames (I or P frame). These B frames, as shown in Figure 2.4, are predicted from both anchor frames to further reduce the resultant bit-rate. Therefore, B frames usually consume the fewest bits compared to P frames and I frames in the same video stream. Both P and B frames are called inter-coded frames. Note that, unlike I frames, P and B frames cannot be decoded independently. Instead, the required anchor frames must rst be decoded and then used in decoding the inter-coded frames. This has two implications to media streaming. First, as shown in Figure 2.4, the temporal dependencies dictate that the B frames cannot be decoded for playback unless all two anchor frames are received and decoded. Thus, if the media server streams out the video data according to their temporal order, the client will need to buffer up B frames to wait for the second anchor frame to arrive before decoding for the B frames can proceed. In practice, the video encoder often re-orders the frame sequence according to the decoding order as shown in Figure 2.5 to reduce the client buffer requirement.
UCC - 12 Encoder In VS .NET
Using Barcode maker for VS .NET Control to generate, create UPC-A Supplement 2 image in Visual Studio .NET applications.
Barcode Drawer In .NET
Using Barcode creator for VS .NET Control to generate, create barcode image in Visual Studio .NET applications.
International Standard Serial Number Generator In .NET
Using Barcode creation for .NET framework Control to generate, create ISSN - 10 image in .NET applications.
Code 3 Of 9 Printer In Visual Basic .NET
Using Barcode encoder for .NET Control to generate, create Code-39 image in Visual Studio .NET applications.
Make EAN128 In Java
Using Barcode printer for Java Control to generate, create GTIN - 128 image in Java applications.
Barcode Creation In VB.NET
Using Barcode creator for VS .NET Control to generate, create bar code image in .NET framework applications.
Encode Code 39 Full ASCII In Java
Using Barcode creator for Java Control to generate, create Code 3 of 9 image in Java applications.