Can NI-Vision Acquisition Software Stream to DVD?
Primary Software: Driver Software>>Vision Acquisition Software
Primary Software Version: N/A
Primary Software Fixed Version: N/A
Secondary Software: N/A
Problem: Is it possible to stream the incoming images from my framegrabber or 1394 camera to a DVD that will play in consumer DVD players?
Solution: The short answer to the question is no, streaming to DVD with IMAQ is not possible and would not be a good solution for several reasons:
- DVD’s use an MPEG codec for video encoding. MPEG encoding uses a technology known as temporal compression that keeps only data that is not redundant between successive frames of video. Thus most frames of video in the MPEG stream do not contain all of the information needed to produce a frame of uncompressed video.
Rather, they rely on information from the frames ahead and behind them to produce the complete image. This kind of compression is very processor intensive and home DVR units are only able to do this in a streaming manner because they have MPEG compression algorithms implemented in hardware.
- The highest quality MPEG compression schemes make use of taking multiple passes through the video, further optimizing the compression with each successive pass. In a real time streaming situation this would not be possible.
- Because MPEG video is highly compressed, the actual pixel values may vary widely from that of the original video. This can make the MPEG video much less useful for image analysis purposes later on.
- DVD’s have a specific file structure that makes use of .VOB containers that contain MPEG video files as well as extra audio tracks, subtitle information, chapter information, etc. When created properly, these files contain all relevant information about the content and length of the VOB file inside the header at the beginning of the file.
If a VOB file was written in a streaming manner, it would not be possible to include this header information in the VOB file.
- PC based DVD writers vary widely in reliability and performance. Trusting a DVD writer to quickly store incoming image data could be highly unreliable should the DVD write fail and lose the entire data run.
- Users will likely want the ability to post process the recorded images. The permanent nature of DVD writing and the high compression and lossy nature of MPEG video data makes it a poor candidate for editing later.
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Report Date: 05/02/2007
Last Updated: 05/03/2007
Document ID: 491M99P9
