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Communications Test & Measurement
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MPEG and Dolby Digital Elementary Stream Analysis To print the Application Note below, click
here (258-KB MProbe is a powerful MPEG bitstream analyzer for video professionals involved in the development, manufacturing, testing, and support of MPEG/DVB or MPEG/ATSC products and solutions such as encoders and multiplexers. As an option to Acterna DTS-A, it combines comprehensive MPEG compliance testing and problem finder tools with an easy-to-use graphical interface. MProbe performs detailed analysis and standard compliance checks of MPEG-1 (ISO/IEC 11172 standard) and MPEG-2 (ISO/IEC 11318 standard) system, MPEG and Dolby Digital audio, and MPEG video streams under full user control. The Transport Stream to be analyzed can be captured with either Acterna DTS-A capture on trigger capability or Acterna DTS-G recorder utility. Notice that the audio and video components extracted with MProbe can be used for simulation purpose with the Acterna DTS-M. As time is money when analyzing MPEG data, MProbe's flexible operating modes allow the user to browse quickly to any location in the stream or queue up a series of streams to run unattended in batch mode. And with MProbe's elegantly designed user interface, all MPEG streams are presented in a hierarchical structure, maintaining the user's point of reference while navigating through large and complex system bitstreams. MProbe is an essential part of any MPEG video and MPEG or AC-3 audio engineer's tool kit. Product developers will depend on its debugging and browsing capabilities throughout the engineering cycle. System integrators and Digital Broadcast solutions providers will rely on MProbe to locate problem data quickly and to verify video data before transmission or distribution. Customer support departments will be empowered with greatly increased trouble-shooting and problem solving capability. Last but not least, TV channels and broadcasters will be able to select and fine-tune encoders and multiplexers. MProbe offers:
Audio ES and PES analysis for MPEG and Dolby Digital systems AC-3, MPEG-1 or MPEG-2 audio components in a Transport Stream can be analyzed as regards headers and audio blocks. MProbe is the first product on the market in the MPEG test & measurement classification to be officially certified by Dolby Laboratories.
Video ES, PES, GOP and I/P/B frame analysis for MPEG-2 systems MProbe is capable of analyzing MPEG video bitstreams across the entire spectrum of levels and profiles, including MPEG2 MP@ML (SDTV), MP@HL (HDTV) and 4:2:2 (Professional). First, decoding PES level headers.
Then providing ES sequence header information.
Inside the Elementary Stream, the user can view the details for each Group Of Pictures (GOP), analysing GOP structures, slices and macro-blocks.
And drill down to macro-blocks to check Size, Quantizer Scale, Motion Vectors etc. for any I, P or B frame along the video.
For a given GOP, MProbe displays statistics such as frame sizes to easily estimate the performance of the encoder. A similar feature is also available for slices and macro-blocks.
Transport, PES and Elementary level buffer-model validation Buffer-models are used to validate encoders. The validation against a model ensures that decoders and set-top boxes may not overflow or underflow when receiving the Transport Stream due to encoding or multiplexing issues. On the other hand, if a stream is not compliant to the buffer model, a decoder is not required to display the video or play the audio to match the original encoded program material and the decoder could show discontinuous jumping or blocking video or have discontinuities in the audio. There are three levels of buffers in the T-STD buffer model: - Transport-level handles transmission reception bursts for a given PID, - Multiplex-level has a processing rate depending on rate/profile for a video, but a fixed rate for audio components; it regulates the bitstream rate; the output is the PES, - Elementary-level output is based on Decoding Time Stamp (DTS) or Presentation Time Stamp (PTS) versus Program Clock Reference (PCR), therefore working at highly variable rate; the output is the video ES. An additional model is based on VBV delay.
Conformance and non-regression testing in batch mode MProbe allows the user to queue up a series of streams to run unattended in batch mode. The analysis results are available as files and can be filtered. This mode allows the user to set up regression test suites.
Keep up-to-date! Bookmark mpeg.acterna.com. For more information or to receive a free evaluation software, please send your contact details to mpeg@jdsu.com. Dolby Digital is a registered trademark of Dolby
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